1.\" $OpenBSD: pf.conf.5,v 1.406 2009/01/31 19:37:12 sobrado Exp $ 2.\" 3.\" Copyright (c) 2002, Daniel Hartmeier 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 10.\" - Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" - Redistributions in binary form must reproduce the above 13.\" copyright notice, this list of conditions and the following 14.\" disclaimer in the documentation and/or other materials provided 15.\" with the distribution. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 18.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 19.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 20.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 21.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 22.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 23.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 24.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 25.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 26.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 27.\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd July 9, 2025 31.Dt PF.CONF 5 32.Os 33.Sh NAME 34.Nm pf.conf 35.Nd packet filter configuration file 36.Sh DESCRIPTION 37The 38.Xr pf 4 39packet filter modifies, drops or passes packets according to rules or 40definitions specified in 41.Nm pf.conf . 42.Sh STATEMENT ORDER 43There are eight types of statements in 44.Nm pf.conf : 45.Bl -tag -width xxxx 46.It Cm Macros 47User-defined variables may be defined and used later, simplifying 48the configuration file. 49Macros must be defined before they are referenced in 50.Nm pf.conf . 51.It Cm Tables 52Tables provide a mechanism for increasing the performance and flexibility of 53rules with large numbers of source or destination addresses. 54.It Cm Options 55Options tune the behaviour of the packet filtering engine. 56.It Cm Ethernet Filtering 57Ethernet filtering provides rule-based blocking or passing of Ethernet packets. 58.It Cm Traffic Normalization Li (e.g. Em scrub ) 59Traffic normalization protects internal machines against inconsistencies 60in Internet protocols and implementations. 61.It Cm Queueing 62Queueing provides rule-based bandwidth control. 63.It Cm Translation Li (Various forms of NAT) 64Translation rules specify how addresses are to be mapped or redirected to 65other addresses. 66.It Cm Packet Filtering 67Packet filtering provides rule-based blocking or passing of packets. 68.El 69.Pp 70With the exception of 71.Cm macros 72and 73.Cm tables , 74the types of statements should be grouped and appear in 75.Nm pf.conf 76in the order shown above, as this matches the operation of the underlying 77packet filtering engine. 78By default 79.Xr pfctl 8 80enforces this order (see 81.Ar set require-order 82below). 83.Pp 84Comments can be put anywhere in the file using a hash mark 85.Pq Sq # , 86and extend to the end of the current line. 87.Pp 88Additional configuration files can be included with the 89.Ic include 90keyword, for example: 91.Bd -literal -offset indent 92include "/etc/pf/sub.filter.conf" 93.Ed 94.Sh MACROS 95Macros can be defined that will later be expanded in context. 96Macro names must start with a letter, and may contain letters, digits 97and underscores. 98Macro names may not be reserved words (for example 99.Ar pass , 100.Ar in , 101.Ar out ) . 102Macros are not expanded inside quotes. 103Ranges of network addresses used in macros that will be expanded in lists 104later on must be quoted with additional simple quotes. 105.Pp 106For example, 107.Bd -literal -offset indent 108ext_if = \&"kue0\&" 109all_ifs = \&"{\&" $ext_if lo0 \&"}\&" 110pass out on $ext_if from any to any 111pass in on $ext_if proto tcp from any to any port 25 112 113usr_lan_range = "'192.0.2.0/24'" 114srv_lan_range = "'198.51.100.0 - 198.51.100.255'" 115nat_ranges = \&"{\&" $usr_lan_range $srv_lan_range \&"}\&" 116nat on $ext_if from $nat_ranges to any -> ($ext_if) 117.Ed 118.Sh TABLES 119Tables are named structures which can hold a collection of addresses and 120networks. 121Lookups against tables in 122.Xr pf 4 123are relatively fast, making a single rule with tables much more efficient, 124in terms of 125processor usage and memory consumption, than a large number of rules which 126differ only in IP address (either created explicitly or automatically by rule 127expansion). 128.Pp 129Tables can be used as the source or destination of filter rules, 130.Ar scrub 131rules 132or 133translation rules such as 134.Ar nat 135or 136.Ar rdr 137(see below for details on the various rule types). 138Tables can also be used for the redirect address of 139.Ar nat 140and 141.Ar rdr 142and in the routing options of filter rules, but not for 143.Ar bitmask 144pools. 145.Pp 146Tables can be defined with any of the following 147.Xr pfctl 8 148mechanisms. 149As with macros, reserved words may not be used as table names. 150.Bl -tag -width "manually" 151.It Ar manually 152Persistent tables can be manually created with the 153.Ar add 154or 155.Ar replace 156option of 157.Xr pfctl 8 , 158before or after the ruleset has been loaded. 159.It Pa pf.conf 160Table definitions can be placed directly in this file, and loaded at the 161same time as other rules are loaded, atomically. 162Table definitions inside 163.Nm pf.conf 164use the 165.Ar table 166statement, and are especially useful to define non-persistent tables. 167The contents of a pre-existing table defined without a list of addresses 168to initialize it is not altered when 169.Nm pf.conf 170is loaded. 171A table initialized with the empty list, 172.Li { } , 173will be cleared on load. 174.El 175.Pp 176Tables may be defined with the following attributes: 177.Bl -tag -width counters 178.It Ar persist 179The 180.Ar persist 181flag forces the kernel to keep the table even when no rules refer to it. 182If the flag is not set, the kernel will automatically remove the table 183when the last rule referring to it is flushed. 184.It Ar const 185The 186.Ar const 187flag prevents the user from altering the contents of the table once it 188has been created. 189Without that flag, 190.Xr pfctl 8 191can be used to add or remove addresses from the table at any time, even 192when running with 193.Xr securelevel 7 194= 2. 195.It Ar counters 196The 197.Ar counters 198flag enables per-address packet and byte counters which can be displayed with 199.Xr pfctl 8 . 200Note that this feature carries significant memory overhead for large tables. 201.El 202.Pp 203For example, 204.Bd -literal -offset indent 205table <private> const { 10/8, 172.16/12, 192.168/16 } 206table <badhosts> persist 207block on fxp0 from { <private>, <badhosts> } to any 208.Ed 209.Pp 210creates a table called private, to hold RFC 1918 private network 211blocks, and a table called badhosts, which is initially empty. 212A filter rule is set up to block all traffic coming from addresses listed in 213either table. 214The private table cannot have its contents changed and the badhosts table 215will exist even when no active filter rules reference it. 216Addresses may later be added to the badhosts table, so that traffic from 217these hosts can be blocked by using 218.Bd -literal -offset indent 219# pfctl -t badhosts -Tadd 204.92.77.111 220.Ed 221.Pp 222A table can also be initialized with an address list specified in one or more 223external files, using the following syntax: 224.Bd -literal -offset indent 225table <spam> persist file \&"/etc/spammers\&" file \&"/etc/openrelays\&" 226block on fxp0 from <spam> to any 227.Ed 228.Pp 229The files 230.Pa /etc/spammers 231and 232.Pa /etc/openrelays 233list IP addresses, one per line. 234Any lines beginning with a # are treated as comments and ignored. 235In addition to being specified by IP address, hosts may also be 236specified by their hostname. 237When the resolver is called to add a hostname to a table, 238.Em all 239resulting IPv4 and IPv6 addresses are placed into the table. 240IP addresses can also be entered in a table by specifying a valid interface 241name, a valid interface group or the 242.Em self 243keyword, in which case all addresses assigned to the interface(s) will be 244added to the table. 245.Sh OPTIONS 246.Xr pf 4 247may be tuned for various situations using the 248.Ar set 249command. 250.Bl -tag -width xxxx 251.It Ar set timeout 252.Pp 253.Bl -tag -width "src.track" -compact 254.It Ar interval 255Interval between purging expired states and fragments. 256.It Ar frag 257Seconds before an unassembled fragment is expired. 258.It Ar src.track 259Length of time to retain a source tracking entry after the last state 260expires. 261.El 262.Pp 263When a packet matches a stateful connection, the seconds to live for the 264connection will be updated to that of the 265.Ar proto.modifier 266which corresponds to the connection state. 267Each packet which matches this state will reset the TTL. 268Tuning these values may improve the performance of the 269firewall at the risk of dropping valid idle connections. 270.Pp 271.Bl -tag -width xxxx -compact 272.It Ar tcp.first 273The state after the first packet. 274.It Ar tcp.opening 275The state after the second packet but before both endpoints have 276acknowledged the connection. 277.It Ar tcp.established 278The fully established state. 279.It Ar tcp.closing 280The state after the first FIN has been sent. 281.It Ar tcp.finwait 282The state after both FINs have been exchanged and the connection is closed. 283Some hosts (notably web servers on Solaris) send TCP packets even after closing 284the connection. 285Increasing 286.Ar tcp.finwait 287(and possibly 288.Ar tcp.closing ) 289can prevent blocking of such packets. 290.It Ar tcp.closed 291The state after one endpoint sends an RST. 292.El 293.Pp 294SCTP timeout are handled similar to TCP, but with its own set of states: 295.Pp 296.Bl -tag -width xxxx -compact 297.It Ar sctp.first 298The state after the first packet. 299.It Ar sctp.opening 300The state before the destination host ever sends a packet. 301.It Ar sctp.established 302The fully established state. 303.It Ar sctp.closing 304The state after the first SHUTDOWN chunk has been sent. 305.It Ar sctp.closed 306The state after SHUTDOWN_ACK has been exchanged and the connection is closed. 307.El 308.Pp 309ICMP and UDP are handled in a fashion similar to TCP, but with a much more 310limited set of states: 311.Pp 312.Bl -tag -width xxxx -compact 313.It Ar udp.first 314The state after the first packet. 315.It Ar udp.single 316The state if the source host sends more than one packet but the destination 317host has never sent one back. 318.It Ar udp.multiple 319The state if both hosts have sent packets. 320.It Ar icmp.first 321The state after the first packet. 322.It Ar icmp.error 323The state after an ICMP error came back in response to an ICMP packet. 324.El 325.Pp 326Other protocols are handled similarly to UDP: 327.Pp 328.Bl -tag -width xxxx -compact 329.It Ar other.first 330.It Ar other.single 331.It Ar other.multiple 332.El 333.Pp 334Timeout values can be reduced adaptively as the number of state table 335entries grows. 336.Pp 337.Bl -tag -width xxxx -compact 338.It Ar adaptive.start 339When the number of state entries exceeds this value, adaptive scaling 340begins. 341All timeout values are scaled linearly with factor 342(adaptive.end - number of states) / (adaptive.end - adaptive.start). 343.It Ar adaptive.end 344When reaching this number of state entries, all timeout values become 345zero, effectively purging all state entries immediately. 346This value is used to define the scale factor, it should not actually 347be reached (set a lower state limit, see below). 348.El 349.Pp 350Adaptive timeouts are enabled by default, with an adaptive.start value 351equal to 60% of the state limit, and an adaptive.end value equal to 352120% of the state limit. 353They can be disabled by setting both adaptive.start and adaptive.end to 0. 354.Pp 355The adaptive timeout values can be defined both globally and for each rule. 356When used on a per-rule basis, the values relate to the number of 357states created by the rule, otherwise to the total number of 358states. 359.Pp 360For example: 361.Bd -literal -offset indent 362set timeout tcp.first 120 363set timeout tcp.established 86400 364set timeout { adaptive.start 60000, adaptive.end 120000 } 365set limit states 100000 366.Ed 367.Pp 368With 90000 state table entries, the timeout values are scaled to 50% 369(tcp.first 60, tcp.established 43200). 370.It Ar set loginterface 371Enable collection of packet and byte count statistics for the given 372interface or interface group. 373These statistics can be viewed using 374.Bd -literal -offset indent 375# pfctl -s info 376.Ed 377.Pp 378In this example 379.Xr pf 4 380collects statistics on the interface named dc0: 381.Bd -literal -offset indent 382set loginterface dc0 383.Ed 384.Pp 385One can disable the loginterface using: 386.Bd -literal -offset indent 387set loginterface none 388.Ed 389.It Ar set limit 390Sets hard limits on the memory pools used by the packet filter. 391See 392.Xr zone 9 393for an explanation of memory pools. 394.Pp 395For example, 396.Bd -literal -offset indent 397set limit states 20000 398.Ed 399.Pp 400sets the maximum number of entries in the memory pool used by state table 401entries (generated by 402.Ar pass 403rules which do not specify 404.Ar no state ) 405to 20000. 406Using 407.Bd -literal -offset indent 408set limit frags 20000 409.Ed 410.Pp 411sets the maximum number of entries in the memory pool used for fragment 412reassembly (generated by the 413.Ar set reassemble 414option or 415.Ar scrub 416rules) to 20000. 417Using 418.Bd -literal -offset indent 419set limit src-nodes 2000 420.Ed 421.Pp 422sets the maximum number of entries in the memory pool used for tracking 423source IP addresses (generated by the 424.Ar sticky-address 425and 426.Ar src.track 427options) to 2000. 428Using 429.Bd -literal -offset indent 430set limit table-entries 100000 431.Ed 432.Pp 433sets the limit on the overall number of addresses that can be stored 434in tables to 100000. 435.Pp 436Various limits can be combined on a single line: 437.Bd -literal -offset indent 438set limit { states 20000, frags 20000, src-nodes 2000 } 439.Ed 440.It Ar set ruleset-optimization 441.Bl -tag -width xxxxxxxx -compact 442.It Ar none 443Disable the ruleset optimizer. 444.It Ar basic 445Enable basic ruleset optimization. 446This is the default behaviour. 447Basic ruleset optimization does four things to improve the 448performance of ruleset evaluations: 449.Pp 450.Bl -enum -compact 451.It 452remove duplicate rules 453.It 454remove rules that are a subset of another rule 455.It 456combine multiple rules into a table when advantageous 457.It 458re-order the rules to improve evaluation performance 459.El 460.Pp 461.It Ar profile 462Uses the currently loaded ruleset as a feedback profile to tailor the 463ordering of quick rules to actual network traffic. 464.El 465.Pp 466It is important to note that the ruleset optimizer will modify the ruleset 467to improve performance. 468A side effect of the ruleset modification is that per-rule accounting 469statistics will have different meanings than before. 470If per-rule accounting is important for billing purposes or whatnot, 471either the ruleset optimizer should not be used or a label field should 472be added to all of the accounting rules to act as optimization barriers. 473.Pp 474Optimization can also be set as a command-line argument to 475.Xr pfctl 8 , 476overriding the settings in 477.Nm . 478.It Ar set optimization 479Optimize state timeouts for one of the following network environments: 480.Pp 481.Bl -tag -width xxxx -compact 482.It Ar normal 483A normal network environment. 484Suitable for almost all networks. 485.It Ar high-latency 486A high-latency environment (such as a satellite connection). 487.It Ar satellite 488Alias for 489.Ar high-latency . 490.It Ar aggressive 491Aggressively expire connections. 492This can greatly reduce the memory usage of the firewall at the cost of 493dropping idle connections early. 494.It Ar conservative 495Extremely conservative settings. 496Avoid dropping legitimate connections at the 497expense of greater memory utilization (possibly much greater on a busy 498network) and slightly increased processor utilization. 499.El 500.Pp 501For example: 502.Bd -literal -offset indent 503set optimization aggressive 504.Ed 505.It Ar set reassemble yes | no Op Cm no-df 506The 507.Cm reassemble 508option is used to enable or disable the reassembly of fragmented packets, 509and can be set to 510.Cm yes 511or 512.Cm no . 513If 514.Cm no-df 515is also specified, fragments with the 516.Dq dont-fragment 517bit set are reassembled too, 518instead of being dropped; 519the reassembled packet will have the 520.Dq dont-fragment 521bit cleared. 522The default value is 523.Cm no . 524.Pp 525This option is ignored if there are pre-FreeBSD 14 526.Cm scrub 527rules present. 528.It Ar set block-policy 529The 530.Ar block-policy 531option sets the default behaviour for the packet 532.Ar block 533action: 534.Pp 535.Bl -tag -width xxxxxxxx -compact 536.It Ar drop 537Packet is silently dropped. 538.It Ar return 539A TCP RST is returned for blocked TCP packets, 540an SCTP ABORT chunk is returned for blocked SCTP packets, 541an ICMP UNREACHABLE is returned for blocked UDP packets, 542and all other packets are silently dropped. 543.El 544.Pp 545The default value is 546.Cm drop . 547.Pp 548For example: 549.Bd -literal -offset indent 550set block-policy return 551.Ed 552.It Ar set fail-policy 553The 554.Ar fail-policy 555option sets the behaviour of rules which should pass a packet but were 556unable to do so. 557This might happen when a nat or route-to rule uses an empty table as list 558of targets or if a rule fails to create state or source node. 559The following 560.Ar block 561actions are possible: 562.Pp 563.Bl -tag -width xxxxxxxx -compact 564.It Ar drop 565Incoming packet is silently dropped. 566.It Ar return 567Incoming packet is dropped and TCP RST is returned for TCP packets, 568an SCTP ABORT chunk is returned for blocked SCTP packets, 569an ICMP UNREACHABLE is returned for UDP packets, 570and no response is sent for other packets. 571.El 572.Pp 573For example: 574.Bd -literal -offset indent 575set fail-policy return 576.Ed 577.It Ar set state-policy 578The 579.Ar state-policy 580option sets the default behaviour for states: 581.Pp 582.Bl -tag -width group-bound -compact 583.It Ar if-bound 584States are bound to interface. 585.It Ar floating 586States can match packets on any interfaces (the default). 587.El 588.Pp 589For example: 590.Bd -literal -offset indent 591set state-policy if-bound 592.Ed 593.It Ar set syncookies never | always | adaptive 594When 595.Cm syncookies 596are active, pf will answer each incoming TCP SYN with a syncookie SYNACK, 597without allocating any resources. 598Upon reception of the client's ACK in response to the syncookie 599SYNACK, pf will evaluate the ruleset and create state if the ruleset 600permits it, complete the three way handshake with the target host and 601continue the connection with synproxy in place. 602This allows pf to be resilient against large synflood attacks which would 603run the state table against its limits otherwise. 604Due to the blind answers to every incoming SYN syncookies share the caveats of 605synproxy, namely seemingly accepting connections that will be dropped later on. 606.Pp 607.Bl -tag -width adaptive -compact 608.It Cm never 609pf will never send syncookie SYNACKs (the default). 610.It Cm always 611pf will always send syncookie SYNACKs. 612.It Cm adaptive 613pf will enable syncookie mode when a given percentage of the state table 614is used up by half-open TCP connections, as in, those that saw the initial 615SYN but didn't finish the three way handshake. 616The thresholds for entering and leaving syncookie mode can be specified using 617.Bd -literal -offset indent 618set syncookies adaptive (start 25%, end 12%) 619.Ed 620.El 621.It Ar set state-defaults 622The 623.Ar state-defaults 624option sets the state options for states created from rules 625without an explicit 626.Ar keep state . 627For example: 628.Bd -literal -offset indent 629set state-defaults no-sync 630.Ed 631.It Ar set hostid 632The 32-bit 633.Ar hostid 634identifies this firewall's state table entries to other firewalls 635in a 636.Xr pfsync 4 637failover cluster. 638By default the hostid is set to a pseudo-random value, however it may be 639desirable to manually configure it, for example to more easily identify the 640source of state table entries. 641.Bd -literal -offset indent 642set hostid 1 643.Ed 644.Pp 645The hostid may be specified in either decimal or hexadecimal. 646.It Ar set require-order 647By default 648.Xr pfctl 8 649enforces an ordering of the statement types in the ruleset to: 650.Em options , 651.Em normalization , 652.Em queueing , 653.Em translation , 654.Em filtering . 655Setting this option to 656.Ar no 657disables this enforcement. 658There may be non-trivial and non-obvious implications to an out of 659order ruleset. 660Consider carefully before disabling the order enforcement. 661.It Ar set fingerprints 662Load fingerprints of known operating systems from the given filename. 663By default fingerprints of known operating systems are automatically 664loaded from 665.Xr pf.os 5 666in 667.Pa /etc 668but can be overridden via this option. 669Setting this option may leave a small period of time where the fingerprints 670referenced by the currently active ruleset are inconsistent until the new 671ruleset finishes loading. 672The default location for fingerprints is 673.Pa /etc/pf.os . 674.Pp 675For example: 676.Pp 677.Dl set fingerprints \&"/etc/pf.os.devel\&" 678.It Ar set skip on Aq Ar ifspec 679List interfaces for which packets should not be filtered. 680Packets passing in or out on such interfaces are passed as if pf was 681disabled, i.e. pf does not process them in any way. 682This can be useful on loopback and other virtual interfaces, when 683packet filtering is not desired and can have unexpected effects. 684For example: 685.Pp 686.Dl set skip on lo0 687.It Ar set debug 688Set the debug 689.Ar level 690to one of the following: 691.Pp 692.Bl -tag -width xxxxxxxxxxxx -compact 693.It Ar none 694Don't generate debug messages. 695.It Ar urgent 696Generate debug messages only for serious errors. 697.It Ar misc 698Generate debug messages for various errors. 699.It Ar loud 700Generate debug messages for common conditions. 701.El 702.It Ar set keepcounters 703Preserve rule counters across rule updates. 704Usually rule counters are reset to zero on every update of the ruleset. 705With 706.Ar keepcounters 707set pf will attempt to find matching rules between old and new rulesets 708and preserve the rule counters. 709.El 710.Sh ETHERNET FILTERING 711.Xr pf 4 712has the ability to 713.Ar block 714and 715.Ar pass 716packets based on attributes of their Ethernet (layer 2) header. 717.Pp 718Each time a packet processed by the packet filter comes in on or 719goes out through an interface, the filter rules are evaluated in 720sequential order, from first to last. 721The last matching rule decides what action is taken. 722If no rule matches the packet, the default action is to pass 723the packet without creating a state. 724.Pp 725The following actions can be used in the filter: 726.Bl -tag -width xxxx 727.It Ar block 728The packet is blocked. 729Unlike for layer 3 traffic the packet is always silently dropped. 730.It Ar pass 731The packet is passed; 732no state is created for layer 2 traffic. 733.El 734.Ss Parameters applicable to layer 2 rules 735The rule parameters specify the packets to which a rule applies. 736A packet always comes in on, or goes out through, one interface. 737Most parameters are optional. 738If a parameter is specified, the rule only applies to packets with 739matching attributes. 740The matching for some parameters can be inverted with the 741.Cm !\& 742operator. 743Certain parameters can be expressed as lists, in which case 744.Xr pfctl 8 745generates all needed rule combinations. 746.Bl -tag -width xxxx 747.It Ar in No or Ar out 748This rule applies to incoming or outgoing packets. 749If neither 750.Ar in 751nor 752.Ar out 753are specified, the rule will match packets in both directions. 754.It Ar quick 755If a packet matches a rule which has the 756.Ar quick 757option set, this rule 758is considered the last matching rule, and evaluation of subsequent rules 759is skipped. 760.It Ar on Aq Ar ifspec 761This rule applies only to packets coming in on, or going out through, this 762particular interface or interface group. 763For more information on interface groups, 764see the 765.Ic group 766keyword in 767.Xr ifconfig 8 . 768.Ar any 769will match any existing interface except loopback ones. 770.It Ar bridge-to Aq interface 771Packets matching this rule will be sent out of the specified interface without 772further processing. 773.It Ar proto Aq Ar protocol 774This rule applies only to packets of this protocol. 775Note that Ethernet protocol numbers are different from those used in 776.Xr ip 4 777and 778.Xr ip6 4 . 779.It Xo 780.Ar from Aq Ar source 781.Ar to Aq Ar dest 782.Xc 783This rule applies only to packets with the specified source and destination 784MAC addresses. 785.It Xo Ar queue Aq Ar queue 786.Xc 787Packets matching this rule will be assigned to the specified queue. 788See 789.Sx QUEUEING 790for setup details. 791.Pp 792.It Ar tag Aq Ar string 793Packets matching this rule will be tagged with the 794specified string. 795The tag acts as an internal marker that can be used to 796identify these packets later on. 797This can be used, for example, to provide trust between 798interfaces and to determine if packets have been 799processed by translation rules. 800Tags are 801.Qq sticky , 802meaning that the packet will be tagged even if the rule 803is not the last matching rule. 804Further matching rules can replace the tag with a 805new one but will not remove a previously applied tag. 806A packet is only ever assigned one tag at a time. 807.It Ar tagged Aq Ar string 808Used to specify that packets must already be tagged with the given tag in order 809to match the rule. 810Inverse tag matching can also be done by specifying the ! operator before the 811tagged keyword. 812.El 813.Sh TRAFFIC NORMALIZATION 814Traffic normalization is a broad umbrella term 815for aspects of the packet filter which deal with 816verifying packets, packet fragments, spoofed traffic, 817and other irregularities. 818.Ss Scrub 819Scrub involves sanitising packet content in such a way 820that there are no ambiguities in packet interpretation on the receiving side. 821It is invoked with the 822.Cm scrub 823option, added to filter rules. 824.Pp 825Parameters are specified enclosed in parentheses. 826At least one of the following parameters must be specified: 827.Bl -tag -width xxxx 828.It Ar no-df 829Clears the 830.Ar dont-fragment 831bit from a matching IP packet. 832Some operating systems are known to generate fragmented packets with the 833.Ar dont-fragment 834bit set. 835This is particularly true with NFS. 836.Ar Scrub 837will drop such fragmented 838.Ar dont-fragment 839packets unless 840.Ar no-df 841is specified. 842.Pp 843Unfortunately some operating systems also generate their 844.Ar dont-fragment 845packets with a zero IP identification field. 846Clearing the 847.Ar dont-fragment 848bit on packets with a zero IP ID may cause deleterious results if an 849upstream router later fragments the packet. 850Using the 851.Ar random-id 852modifier (see below) is recommended in combination with the 853.Ar no-df 854modifier to ensure unique IP identifiers. 855.It Ar min-ttl Aq Ar number 856Enforces a minimum TTL for matching IP packets. 857.It Ar max-mss Aq Ar number 858Enforces a maximum MSS for matching TCP packets. 859.It Xo Ar set-tos Aq Ar string 860.No \*(Ba Aq Ar number 861.Xc 862Enforces a 863.Em TOS 864for matching IP packets. 865.Em TOS 866may be 867given as one of 868.Ar critical , 869.Ar inetcontrol , 870.Ar lowdelay , 871.Ar netcontrol , 872.Ar throughput , 873.Ar reliability , 874or one of the DiffServ Code Points: 875.Ar ef , 876.Ar va , 877.Ar af11 No ... Ar af43 , 878.Ar cs0 No ... Ar cs7 ; 879or as either hex or decimal. 880.It Ar random-id 881Replaces the IP identification field with random values to compensate 882for predictable values generated by many hosts. 883This option only applies to packets that are not fragmented 884after the optional fragment reassembly. 885.It Ar reassemble tcp 886Statefully normalizes TCP connections. 887.Ar reassemble tcp 888performs the following normalizations: 889.Pp 890.Bl -tag -width timeout -compact 891.It ttl 892Neither side of the connection is allowed to reduce their IP TTL. 893An attacker may send a packet such that it reaches the firewall, affects 894the firewall state, and expires before reaching the destination host. 895.Ar reassemble tcp 896will raise the TTL of all packets back up to the highest value seen on 897the connection. 898.It timestamp modulation 899Modern TCP stacks will send a timestamp on every TCP packet and echo 900the other endpoint's timestamp back to them. 901Many operating systems will merely start the timestamp at zero when 902first booted, and increment it several times a second. 903The uptime of the host can be deduced by reading the timestamp and multiplying 904by a constant. 905Also observing several different timestamps can be used to count hosts 906behind a NAT device. 907And spoofing TCP packets into a connection requires knowing or guessing 908valid timestamps. 909Timestamps merely need to be monotonically increasing and not derived off a 910guessable base time. 911.Ar reassemble tcp 912will cause 913.Ar scrub 914to modulate the TCP timestamps with a random number. 915.It extended PAWS checks 916There is a problem with TCP on long fat pipes, in that a packet might get 917delayed for longer than it takes the connection to wrap its 32-bit sequence 918space. 919In such an occurrence, the old packet would be indistinguishable from a 920new packet and would be accepted as such. 921The solution to this is called PAWS: Protection Against Wrapped Sequence 922numbers. 923It protects against it by making sure the timestamp on each packet does 924not go backwards. 925.Ar reassemble tcp 926also makes sure the timestamp on the packet does not go forward more 927than the RFC allows. 928By doing this, 929.Xr pf 4 930artificially extends the security of TCP sequence numbers by 10 to 18 931bits when the host uses appropriately randomized timestamps, since a 932blind attacker would have to guess the timestamp as well. 933.El 934.El 935.Pp 936For example, 937.Bd -literal -offset indent 938match in all scrub (no-df random-id max-mss 1440) 939.Ed 940.Ss Scrub ruleset (pre-FreeBSD 14) 941In order to maintain compatibility with older releases of FreeBSD 942.Ar scrub 943rules can also be specified in their own ruleset. 944In such case they are invoked with the 945.Ar scrub 946directive. 947If there are such rules present they determine packet reassembly behaviour. 948When no such rules are present the option 949.Ar set reassembly 950takes precedence. 951The 952.Ar scrub 953rules can take all parameters specified above for a 954.Ar scrub 955option of filter rules and 2 more parameters controlling fragment reassembly: 956.Bl -tag -width xxxx 957.It Ar fragment reassemble 958Using 959.Ar scrub 960rules, fragments can be reassembled by normalization. 961In this case, fragments are buffered until they form a complete 962packet, and only the completed packet is passed on to the filter. 963The advantage is that filter rules have to deal only with complete 964packets, and can ignore fragments. 965The drawback of caching fragments is the additional memory cost. 966This is the default behaviour unless no fragment reassemble is specified. 967.It Ar no fragment reassemble 968Do not reassemble fragments. 969.El 970.Pp 971For example, 972.Bd -literal -offset indent 973scrub in on $ext_if all fragment reassemble 974.Ed 975.Pp 976The 977.Ar no 978option prefixed to a scrub rule causes matching packets to remain unscrubbed, 979much in the same way as 980.Ar drop quick 981works in the packet filter (see below). 982This mechanism should be used when it is necessary to exclude specific packets 983from broader scrub rules. 984.Pp 985.Ar scrub 986rules in the 987.Ar scrub 988ruleset are evaluated for every packet before stateful filtering. 989This means excessive usage of them will cause performance penalty. 990.Ar scrub reassemble tcp 991rules must not have the direction (in/out) specified. 992.Sh QUEUEING with ALTQ 993The ALTQ system is currently not available in the GENERIC kernel nor as 994loadable modules. 995In order to use the herein after called queueing options one has to use a 996custom built kernel. 997Please refer to 998.Xr altq 4 999to learn about the related kernel options. 1000.Pp 1001Packets can be assigned to queues for the purpose of bandwidth 1002control. 1003At least two declarations are required to configure queues, and later 1004any packet filtering rule can reference the defined queues by name. 1005During the filtering component of 1006.Nm pf.conf , 1007the last referenced 1008.Ar queue 1009name is where any packets from 1010.Ar pass 1011rules will be queued, while for 1012.Ar block 1013rules it specifies where any resulting ICMP or TCP RST 1014packets should be queued. 1015The 1016.Ar scheduler 1017defines the algorithm used to decide which packets get delayed, dropped, or 1018sent out immediately. 1019There are three 1020.Ar schedulers 1021currently supported. 1022.Bl -tag -width xxxx 1023.It Ar cbq 1024Class Based Queueing. 1025.Ar Queues 1026attached to an interface build a tree, thus each 1027.Ar queue 1028can have further child 1029.Ar queues . 1030Each queue can have a 1031.Ar priority 1032and a 1033.Ar bandwidth 1034assigned. 1035.Ar Priority 1036mainly controls the time packets take to get sent out, while 1037.Ar bandwidth 1038has primarily effects on throughput. 1039.Ar cbq 1040achieves both partitioning and sharing of link bandwidth 1041by hierarchically structured classes. 1042Each class has its own 1043.Ar queue 1044and is assigned its share of 1045.Ar bandwidth . 1046A child class can borrow bandwidth from its parent class 1047as long as excess bandwidth is available 1048(see the option 1049.Ar borrow , 1050below). 1051.It Ar priq 1052Priority Queueing. 1053.Ar Queues 1054are flat attached to the interface, thus, 1055.Ar queues 1056cannot have further child 1057.Ar queues . 1058Each 1059.Ar queue 1060has a unique 1061.Ar priority 1062assigned, ranging from 0 to 15. 1063Packets in the 1064.Ar queue 1065with the highest 1066.Ar priority 1067are processed first. 1068.It Ar hfsc 1069Hierarchical Fair Service Curve. 1070.Ar Queues 1071attached to an interface build a tree, thus each 1072.Ar queue 1073can have further child 1074.Ar queues . 1075Each queue can have a 1076.Ar priority 1077and a 1078.Ar bandwidth 1079assigned. 1080.Ar Priority 1081mainly controls the time packets take to get sent out, while 1082.Ar bandwidth 1083primarily affects throughput. 1084.Ar hfsc 1085supports both link-sharing and guaranteed real-time services. 1086It employs a service curve based QoS model, 1087and its unique feature is an ability to decouple 1088.Ar delay 1089and 1090.Ar bandwidth 1091allocation. 1092.El 1093.Pp 1094The interfaces on which queueing should be activated are declared using 1095the 1096.Ar altq on 1097declaration. 1098.Ar altq on 1099has the following keywords: 1100.Bl -tag -width xxxx 1101.It Aq Ar interface 1102Queueing is enabled on the named interface. 1103.It Aq Ar scheduler 1104Specifies which queueing scheduler to use. 1105Currently supported values 1106are 1107.Ar cbq 1108for Class Based Queueing, 1109.Ar priq 1110for Priority Queueing and 1111.Ar hfsc 1112for the Hierarchical Fair Service Curve scheduler. 1113.It Ar bandwidth Aq Ar bw 1114The maximum bitrate for all queues on an 1115interface may be specified using the 1116.Ar bandwidth 1117keyword. 1118The value can be specified as an absolute value or as a 1119percentage of the interface bandwidth. 1120When using an absolute value, the suffixes 1121.Ar b , 1122.Ar Kb , 1123.Ar Mb , 1124and 1125.Ar Gb 1126are used to represent bits, kilobits, megabits, and 1127gigabits per second, respectively. 1128The value must not exceed the interface bandwidth. 1129If 1130.Ar bandwidth 1131is not specified, the interface bandwidth is used 1132(but take note that some interfaces do not know their bandwidth, 1133or can adapt their bandwidth rates). 1134.It Ar qlimit Aq Ar limit 1135The maximum number of packets held in the queue. 1136The default is 50. 1137.It Ar tbrsize Aq Ar size 1138Adjusts the size, in bytes, of the token bucket regulator. 1139If not specified, heuristics based on the 1140interface bandwidth are used to determine the size. 1141.It Ar queue Aq Ar list 1142Defines a list of subqueues to create on an interface. 1143.El 1144.Pp 1145In the following example, the interface dc0 1146should queue up to 5Mbps in four second-level queues using 1147Class Based Queueing. 1148Those four queues will be shown in a later example. 1149.Bd -literal -offset indent 1150altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh } 1151.Ed 1152.Pp 1153Once interfaces are activated for queueing using the 1154.Ar altq 1155directive, a sequence of 1156.Ar queue 1157directives may be defined. 1158The name associated with a 1159.Ar queue 1160must match a queue defined in the 1161.Ar altq 1162directive (e.g. mail), or, except for the 1163.Ar priq 1164.Ar scheduler , 1165in a parent 1166.Ar queue 1167declaration. 1168The following keywords can be used: 1169.Bl -tag -width xxxx 1170.It Ar on Aq Ar interface 1171Specifies the interface the queue operates on. 1172If not given, it operates on all matching interfaces. 1173.It Ar bandwidth Aq Ar bw 1174Specifies the maximum bitrate to be processed by the queue. 1175This value must not exceed the value of the parent 1176.Ar queue 1177and can be specified as an absolute value or a percentage of the parent 1178queue's bandwidth. 1179If not specified, defaults to 100% of the parent queue's bandwidth. 1180The 1181.Ar priq 1182scheduler does not support bandwidth specification. 1183.It Ar priority Aq Ar level 1184Between queues a priority level can be set. 1185For 1186.Ar cbq 1187and 1188.Ar hfsc , 1189the range is 0 to 7 and for 1190.Ar priq , 1191the range is 0 to 15. 1192The default for all is 1. 1193.Ar Priq 1194queues with a higher priority are always served first. 1195.Ar Cbq 1196and 1197.Ar Hfsc 1198queues with a higher priority are preferred in the case of overload. 1199.It Ar qlimit Aq Ar limit 1200The maximum number of packets held in the queue. 1201The default is 50. 1202.El 1203.Pp 1204The 1205.Ar scheduler 1206can get additional parameters with 1207.Xo Aq Ar scheduler 1208.Pf ( Aq Ar parameters ) . 1209.Xc 1210Parameters are as follows: 1211.Bl -tag -width Fl 1212.It Ar default 1213Packets not matched by another queue are assigned to this one. 1214Exactly one default queue is required. 1215.It Ar red 1216Enable RED (Random Early Detection) on this queue. 1217RED drops packets with a probability proportional to the average 1218queue length. 1219.It Ar rio 1220Enables RIO on this queue. 1221RIO is RED with IN/OUT, thus running 1222RED two times more than RIO would achieve the same effect. 1223RIO is currently not supported in the GENERIC kernel. 1224.It Ar ecn 1225Enables ECN (Explicit Congestion Notification) on this queue. 1226ECN implies RED. 1227.El 1228.Pp 1229The 1230.Ar cbq 1231.Ar scheduler 1232supports an additional option: 1233.Bl -tag -width Fl 1234.It Ar borrow 1235The queue can borrow bandwidth from the parent. 1236.El 1237.Pp 1238The 1239.Ar hfsc 1240.Ar scheduler 1241supports some additional options: 1242.Bl -tag -width Fl 1243.It Ar realtime Aq Ar sc 1244The minimum required bandwidth for the queue. 1245.It Ar upperlimit Aq Ar sc 1246The maximum allowed bandwidth for the queue. 1247.It Ar linkshare Aq Ar sc 1248The bandwidth share of a backlogged queue. 1249.El 1250.Pp 1251.Aq Ar sc 1252is an acronym for 1253.Ar service curve . 1254.Pp 1255The format for service curve specifications is 1256.Ar ( m1 , d , m2 ) . 1257.Ar m2 1258controls the bandwidth assigned to the queue. 1259.Ar m1 1260and 1261.Ar d 1262are optional and can be used to control the initial bandwidth assignment. 1263For the first 1264.Ar d 1265milliseconds the queue gets the bandwidth given as 1266.Ar m1 , 1267afterwards the value given in 1268.Ar m2 . 1269.Pp 1270Furthermore, with 1271.Ar cbq 1272and 1273.Ar hfsc , 1274child queues can be specified as in an 1275.Ar altq 1276declaration, thus building a tree of queues using a part of 1277their parent's bandwidth. 1278.Pp 1279Packets can be assigned to queues based on filter rules by using the 1280.Ar queue 1281keyword. 1282Normally only one 1283.Ar queue 1284is specified; when a second one is specified it will instead be used for 1285packets which have a 1286.Em TOS 1287of 1288.Em lowdelay 1289and for TCP ACKs with no data payload. 1290.Pp 1291To continue the previous example, the examples below would specify the 1292four referenced 1293queues, plus a few child queues. 1294Interactive 1295.Xr ssh 1 1296sessions get priority over bulk transfers like 1297.Xr scp 1 1298and 1299.Xr sftp 1 . 1300The queues may then be referenced by filtering rules (see 1301.Sx PACKET FILTERING 1302below). 1303.Bd -literal 1304queue std bandwidth 10% cbq(default) 1305queue http bandwidth 60% priority 2 cbq(borrow red) \e 1306 { employees, developers } 1307queue developers bandwidth 75% cbq(borrow) 1308queue employees bandwidth 15% 1309queue mail bandwidth 10% priority 0 cbq(borrow ecn) 1310queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk } 1311queue ssh_interactive bandwidth 50% priority 7 cbq(borrow) 1312queue ssh_bulk bandwidth 50% priority 0 cbq(borrow) 1313 1314block return out on dc0 inet all queue std 1315pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e 1316 queue developers 1317pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e 1318 queue employees 1319pass out on dc0 inet proto tcp from any to any port 22 \e 1320 queue(ssh_bulk, ssh_interactive) 1321pass out on dc0 inet proto tcp from any to any port 25 \e 1322 queue mail 1323.Ed 1324.Sh QUEUEING with dummynet 1325Queueing can also be done with 1326.Xr dummynet 4 . 1327Queues and pipes can be created with 1328.Xr dnctl 8 . 1329.Pp 1330Packets can be assigned to queues and pipes using 1331.Ar dnqueue 1332and 1333.Ar dnpipe 1334respectively. 1335.Pp 1336Both 1337.Ar dnqueue 1338and 1339.Ar dnpipe 1340take either a single pipe or queue number or two numbers as arguments. 1341The first pipe or queue number will be used to shape the traffic in the rule 1342direction, the second will be used to shape the traffic in the reverse 1343direction. 1344If the rule does not specify a direction the first packet to create state will 1345be shaped according to the first number, and the response traffic according to 1346the second. 1347.Pp 1348If the 1349.Xr dummynet 4 1350module is not loaded any traffic sent into a queue or pipe will be dropped. 1351.Sh TRANSLATION 1352Translation options modify either the source or destination address and 1353port of the packets associated with a stateful connection. 1354.Xr pf 4 1355modifies the specified address and/or port in the packet and recalculates 1356IP, TCP, and UDP checksums as necessary. 1357.Pp 1358If specified on a 1359.Ic match 1360rule, subsequent rules will see packets as they look 1361after any addresses and ports have been translated. 1362These rules will therefore have to filter based on the translated 1363address and port number. 1364.Pp 1365The state entry created permits 1366.Xr pf 4 1367to keep track of the original address for traffic associated with that state 1368and correctly direct return traffic for that connection. 1369.Pp 1370Various types of translation are possible with pf: 1371.Bl -tag -width xxxx 1372.It Ar af-to 1373Translation between different address families (NAT64) is handled 1374using 1375.Ar af-to 1376rules. 1377Because address family translation overrides the routing table, it's 1378only possible to use 1379.Ar af-to 1380on inbound rules, and a source address of the resulting translation 1381must always be specified. 1382.Pp 1383The optional second argument is the host or subnet the original 1384addresses are translated into for the destination. 1385The lowest bits of the original destination address form the host 1386part of the new destination address according to the specified subnet. 1387It is possible to embed a complete IPv4 address into an IPv6 address 1388using a network prefix of /96 or smaller. 1389.Pp 1390When a destination address is not specified, it is assumed that the host 1391part is 32-bit long. 1392For IPv6 to IPv4 translation this would mean using only the lower 32 1393bits of the original IPv6 destination address. 1394For IPv4 to IPv6 translation the destination subnet defaults to the 1395subnet of the new IPv6 source address with a prefix length of /96. 1396See RFC 6052 Section 2.2 for details on how the prefix determines the 1397destination address encoding. 1398.Pp 1399For example, the following rules are identical: 1400.Bd -literal -offset indent 1401pass in inet af-to inet6 from 2001:db8::1 to 2001:db8::/96 1402pass in inet af-to inet6 from 2001:db8::1 1403.Ed 1404.Pp 1405In the above example the matching IPv4 packets will be modified to 1406have a source address of 2001:db8::1 and a destination address will 1407get prefixed with 2001:db8::/96, e.g. 198.51.100.100 will be 1408translated to 2001:db8::c633:6464. 1409.Pp 1410In the reverse case the following rules are identical: 1411.Bd -literal -offset indent 1412pass in inet6 from any to 64:ff9b::/96 af-to inet \e 1413 from 198.51.100.1 to 0.0.0.0/0 1414pass in inet6 from any to 64:ff9b::/96 af-to inet \e 1415 from 198.51.100.1 1416.Ed 1417.Pp 1418The destination IPv4 address is assumed to be embedded inside the 1419original IPv6 destination address, e.g. 64:ff9b::c633:6464 will be 1420translated to 198.51.100.100. 1421.Pp 1422The current implementation will only extract IPv4 addresses from the 1423IPv6 addresses with a prefix length of /96 and greater. 1424.It Ar binat 1425A 1426.Ar binat-to 1427rule specifies a bidirectional mapping between an external IP netblock 1428and an internal IP netblock. 1429It expands to an outbound 1430.Ar nat-to 1431rule and an inbound 1432.Ar rdr-to 1433rule. 1434.It Ar nat-to 1435A 1436.Ar nat-to 1437option specifies that IP addresses are to be changed as the packet 1438traverses the given interface. 1439This technique allows one or more IP addresses 1440on the translating host to support network traffic for a larger range of 1441machines on an "inside" network. 1442Although in theory any IP address can be used on the inside, it is strongly 1443recommended that one of the address ranges defined by RFC 1918 be used. 1444These netblocks are: 1445.Bd -literal -offset indent 144610.0.0.0 - 10.255.255.255 (all of net 10.0.0.0, i.e., 10.0.0.0/8) 1447172.16.0.0 - 172.31.255.255 (i.e., 172.16.0.0/12) 1448192.168.0.0 - 192.168.255.255 (i.e., 192.168.0.0/16) 1449.Ed 1450.Pp 1451.Ar nat-to 1452is usually applied outbound. 1453If applied inbound, nat-to to a local IP address is not supported. 1454.It Pa rdr-to 1455The packet is redirected to another destination and possibly a 1456different port. 1457.Ar rdr-to 1458can optionally specify port ranges instead of single ports. 1459For instance: 1460.Bd -literal -offset indent 1461match in ... port 2000:2999 rdr-to ... port 4000 1462.Ed 1463redirects ports 2000 to 2999 (inclusive) to port 4000. 1464.Bd -literal -offset indent 1465qmatch in ... port 2000:2999 rdr-to ... port 4000:* 1466.Ed 1467redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999. 1468.El 1469.Pp 1470.Ar rdr-to 1471is usually applied inbound. 1472If applied outbound, rdr-to to a local IP address is not supported. 1473In addition to modifying the address, some translation rules may modify 1474source or destination ports for 1475.Xr tcp 4 1476or 1477.Xr udp 4 1478connections; implicitly in the case of 1479.Ar nat-to 1480options and both implicitly and explicitly in the case of 1481.Ar rdr-to 1482ones. 1483A 1484.Ar rdr-to 1485opion may cause the source port to be modified if doing so avoids a conflict 1486with an existing connection. 1487A random source port in the range 50001-65535 is chosen in this case. 1488Port numbers are never translated with a 1489.Ar binat-to 1490option. 1491.Pp 1492Note that redirecting external incoming connections to the loopback 1493address, as in 1494.Bd -literal -offset indent 1495pass in on egress proto tcp from any to any port smtp \e 1496 rdr-to 127.0.0.1 port spamd 1497.Ed 1498.Pp 1499will effectively allow an external host to connect to daemons 1500bound solely to the loopback address, circumventing the traditional 1501blocking of such connections on a real interface. 1502Unless this effect is desired, any of the local non-loopback addresses 1503should be used as redirection target instead, which allows external 1504connections only to daemons bound to this address or not bound to 1505any address. 1506.Pp 1507See 1508.Sx TRANSLATION EXAMPLES 1509below. 1510.Ss NAT ruleset (pre-FreeBSD 15) 1511In order to maintain compatibility with older releases of FreeBSD 1512.Ar NAT 1513rules can also be specified in their own ruleset. 1514A stateful connection is automatically created to track packets matching 1515such a rule as long as they are not blocked by the filtering section of 1516.Nm pf.conf . 1517Since translation occurs before filtering the filter 1518engine will see packets as they look after any 1519addresses and ports have been translated. 1520Filter rules will therefore have to filter based on the translated 1521address and port number. 1522Packets that match a translation rule are only automatically passed if 1523the 1524.Ar pass 1525modifier is given, otherwise they are 1526still subject to 1527.Ar block 1528and 1529.Ar pass 1530rules. 1531.Pp 1532The following rules can be defined in the NAT ruleset: 1533.Ar binat , 1534.Ar nat , 1535and 1536.Ar rdr . 1537They have the same effect as 1538.Ar binat-to , 1539.Ar nat-to 1540and 1541.Ar rdr-to 1542options for filter rules. 1543.Pp 1544The 1545.Ar no 1546option prefixed to a translation rule causes packets to remain untranslated, 1547much in the same way as 1548.Ar drop quick 1549works in the packet filter. 1550If no rule matches the packet it is passed to the filter engine unmodified. 1551.Pp 1552Evaluation order of the translation rules is dependent on the type 1553of the translation rules and of the direction of a packet. 1554.Ar binat 1555rules are always evaluated first. 1556Then either the 1557.Ar rdr 1558rules are evaluated on an inbound packet or the 1559.Ar nat 1560rules on an outbound packet. 1561Rules of the same type are evaluated in the same order in which they 1562appear in the ruleset. 1563The first matching rule decides what action is taken. 1564.Pp 1565Translation rules apply only to packets that pass through 1566the specified interface, and if no interface is specified, 1567translation is applied to packets on all interfaces. 1568For instance, redirecting port 80 on an external interface to an internal 1569web server will only work for connections originating from the outside. 1570Connections to the address of the external interface from local hosts will 1571not be redirected, since such packets do not actually pass through the 1572external interface. 1573Redirections cannot reflect packets back through the interface they arrive 1574on, they can only be redirected to hosts connected to different interfaces 1575or to the firewall itself. 1576.Pp 1577See 1578.Sx COMPATIBILITY TRANSLATION EXAMPLES 1579below. 1580.Sh PACKET FILTERING 1581.Xr pf 4 1582has the ability to 1583.Ar block 1584, 1585.Ar pass 1586and 1587.Ar match 1588packets based on attributes of their layer 3 (see 1589.Xr ip 4 1590and 1591.Xr ip6 4 ) 1592and layer 4 (see 1593.Xr icmp 4 , 1594.Xr icmp6 4 , 1595.Xr tcp 4 , 1596.Xr sctp 4 , 1597.Xr udp 4 ) 1598headers. 1599In addition, packets may also be 1600assigned to queues for the purpose of bandwidth control. 1601.Pp 1602For each packet processed by the packet filter, the filter rules are 1603evaluated in sequential order, from first to last. 1604For 1605.Ar block 1606and 1607.Ar pass 1608, the last matching rule decides what action is taken. 1609For 1610.Ar match 1611, rules are evaluated every time they match; the pass/block state of a packet 1612remains unchanged. 1613If no rule matches the packet, the default action is to pass 1614the packet. 1615.Pp 1616The following actions can be used in the filter: 1617.Bl -tag -width xxxx 1618.It Ar block 1619The packet is blocked. 1620There are a number of ways in which a 1621.Ar block 1622rule can behave when blocking a packet. 1623The default behaviour is to 1624.Ar drop 1625packets silently, however this can be overridden or made 1626explicit either globally, by setting the 1627.Ar block-policy 1628option, or on a per-rule basis with one of the following options: 1629.Pp 1630.Bl -tag -width xxxx -compact 1631.It Ar drop 1632The packet is silently dropped. 1633.It Ar return-rst 1634This applies only to 1635.Xr tcp 4 1636packets, and issues a TCP RST which closes the 1637connection. 1638.It Ar return-icmp 1639.It Ar return-icmp6 1640This causes ICMP messages to be returned for packets which match the rule. 1641By default this is an ICMP UNREACHABLE message, however this 1642can be overridden by specifying a message as a code or number. 1643.It Ar return 1644This causes a TCP RST to be returned for 1645.Xr tcp 4 1646packets, an SCTP ABORT for SCTP 1647and an ICMP UNREACHABLE for UDP and other packets. 1648.El 1649.Pp 1650Options returning ICMP packets currently have no effect if 1651.Xr pf 4 1652operates on a 1653.Xr if_bridge 4 , 1654as the code to support this feature has not yet been implemented. 1655.Pp 1656The simplest mechanism to block everything by default and only pass 1657packets that match explicit rules is specify a first filter rule of: 1658.Bd -literal -offset indent 1659block all 1660.Ed 1661.It Ar match 1662The packet is matched. 1663This mechanism is used to provide fine grained filtering without altering the 1664block/pass state of a packet. 1665.Ar match 1666rules differ from 1667.Ar block 1668and 1669.Ar pass 1670rules in that parameters are set for every rule a packet matches, not only 1671on the last matching rule. 1672For the following parameters, this means that the parameter effectively becomes 1673"sticky" until explicitly overridden: 1674.Ar nat-to , 1675.Ar binat-to , 1676.Ar rdr-to , 1677.Ar queue , 1678.Ar dnpipe , 1679.Ar dnqueue , 1680.Ar rtable , 1681.Ar scrub 1682. 1683.It Ar pass 1684The packet is passed; 1685state is created unless the 1686.Ar no state 1687option is specified. 1688.El 1689.Pp 1690By default 1691.Xr pf 4 1692filters packets statefully; the first time a packet matches a 1693.Ar pass 1694rule, a state entry is created; for subsequent packets the filter checks 1695whether the packet matches any state. 1696If it does, the packet is passed without evaluation of any rules. 1697After the connection is closed or times out, the state entry is automatically 1698removed. 1699.Pp 1700This has several advantages. 1701For TCP connections, comparing a packet to a state involves checking 1702its sequence numbers, as well as TCP timestamps if a 1703.Ar scrub reassemble tcp 1704rule applies to the connection. 1705If these values are outside the narrow windows of expected 1706values, the packet is dropped. 1707This prevents spoofing attacks, such as when an attacker sends packets with 1708a fake source address/port but does not know the connection's sequence 1709numbers. 1710Similarly, 1711.Xr pf 4 1712knows how to match ICMP replies to states. 1713For example, 1714.Bd -literal -offset indent 1715pass out inet proto icmp all icmp-type echoreq 1716.Ed 1717.Pp 1718allows echo requests (such as those created by 1719.Xr ping 8 ) 1720out statefully, and matches incoming echo replies correctly to states. 1721.Pp 1722Also, looking up states is usually faster than evaluating rules. 1723.Pp 1724Furthermore, correct handling of ICMP error messages is critical to 1725many protocols, particularly TCP. 1726.Xr pf 4 1727matches ICMP error messages to the correct connection, checks them against 1728connection parameters, and passes them if appropriate. 1729For example if an ICMP source quench message referring to a stateful TCP 1730connection arrives, it will be matched to the state and get passed. 1731.Pp 1732Finally, state tracking is required for 1733.Ar nat , binat No and Ar rdr 1734rules, in order to track address and port translations and reverse the 1735translation on returning packets. 1736.Pp 1737.Xr pf 4 1738will also create state for other protocols which are effectively stateless by 1739nature. 1740UDP packets are matched to states using only host addresses and ports, 1741and other protocols are matched to states using only the host addresses. 1742.Pp 1743If stateless filtering of individual packets is desired, 1744the 1745.Ar no state 1746keyword can be used to specify that state will not be created 1747if this is the last matching rule. 1748A number of parameters can also be set to affect how 1749.Xr pf 4 1750handles state tracking. 1751See 1752.Sx STATEFUL TRACKING OPTIONS 1753below for further details. 1754.Ss Parameters 1755The rule parameters specify the packets to which a rule applies. 1756A packet always comes in on, or goes out through, one interface. 1757Most parameters are optional. 1758If a parameter is specified, the rule only applies to packets with 1759matching attributes. 1760Certain parameters can be expressed as lists, in which case 1761.Xr pfctl 8 1762generates all needed rule combinations. 1763.Bl -tag -width xxxx 1764.It Ar in No or Ar out 1765This rule applies to incoming or outgoing packets. 1766If neither 1767.Ar in 1768nor 1769.Ar out 1770are specified, the rule will match packets in both directions. 1771.It Ar log Pq Cm all | matches | to Ao Ar interface Ac | Cm user 1772In addition to any action specified, 1773log the packet. 1774Only the packet that establishes the state is logged, 1775unless the 1776.Ar no state 1777option is specified. 1778The logged packets are sent to a 1779.Xr pflog 4 1780interface, by default pflog0; 1781pflog0 is monitored by the 1782.Xr pflogd 8 1783logging daemon which logs to the file 1784.Pa /var/log/pflog 1785in 1786.Xr pcap 3 1787binary format. 1788.Pp 1789The keywords 1790.Cm all , matches , to , 1791and 1792.Cm user 1793are optional and can be combined using commas, 1794but must be enclosed in parentheses if given. 1795.Pp 1796Use 1797.Cm all 1798to force logging of all packets for a connection. 1799This is not necessary when 1800.Ar no state 1801is explicitly specified. 1802.Pp 1803If 1804.Cm matches 1805is specified, 1806it logs the packet on all subsequent matching rules. 1807It is often combined with 1808.Cm to Aq Ar interface 1809to avoid adding noise to the default log file. 1810.Pp 1811The keyword 1812.Cm user 1813logs the 1814.Ux 1815user ID of the user that owns the socket and the PID of the process that 1816has the socket open where the packet is sourced from or destined to 1817(depending on which socket is local). 1818This is in addition to the normal information logged. 1819.Pp 1820Only the first packet 1821logged via 1822.Ar log (all, user) 1823will have the user credentials logged when using stateful matching. 1824.Pp 1825To specify a logging interface other than pflog0, 1826use the syntax 1827.Cm to Aq Ar interface . 1828.It Ar quick 1829If a packet matches a rule which has the 1830.Ar quick 1831option set, this rule 1832is considered the last matching rule, and evaluation of subsequent rules 1833is skipped. 1834.It Ar on Aq Ar interface 1835This rule applies only to packets coming in on, or going out through, this 1836particular interface or interface group. 1837For more information on interface groups, 1838see the 1839.Ic group 1840keyword in 1841.Xr ifconfig 8 . 1842.Ar any 1843will match any existing interface except loopback ones. 1844.It Aq Ar af 1845This rule applies only to packets of this address family. 1846Supported values are 1847.Ar inet 1848and 1849.Ar inet6 . 1850.It Ar proto Aq Ar protocol 1851This rule applies only to packets of this protocol. 1852Common protocols are 1853.Xr icmp 4 , 1854.Xr icmp6 4 , 1855.Xr tcp 4 , 1856.Xr sctp 4 , 1857and 1858.Xr udp 4 . 1859For a list of all the protocol name to number mappings used by 1860.Xr pfctl 8 , 1861see the file 1862.Pa /etc/protocols . 1863.It Xo 1864.Ar from Aq Ar source 1865.Ar port Aq Ar source 1866.Ar os Aq Ar source 1867.Ar to Aq Ar dest 1868.Ar port Aq Ar dest 1869.Xc 1870This rule applies only to packets with the specified source and destination 1871addresses and ports. 1872.Pp 1873Addresses can be specified in CIDR notation (matching netblocks), as 1874symbolic host names, interface names or interface group names, or as any 1875of the following keywords: 1876.Pp 1877.Bl -tag -width xxxxxxxxxxxxxx -compact 1878.It Ar any 1879Any address. 1880.It Ar no-route 1881Any address which is not currently routable. 1882.It Ar urpf-failed 1883Any source address that fails a unicast reverse path forwarding (URPF) 1884check, i.e. packets coming in on an interface other than that which holds 1885the route back to the packet's source address. 1886.It Ar self 1887Expands to all addresses assigned to all interfaces. 1888.It Aq Ar table 1889Any address that matches the given table. 1890.El 1891.Pp 1892Ranges of addresses are specified by using the 1893.Sq - 1894operator. 1895For instance: 1896.Dq 10.1.1.10 - 10.1.1.12 1897means all addresses from 10.1.1.10 to 10.1.1.12, 1898hence addresses 10.1.1.10, 10.1.1.11, and 10.1.1.12. 1899.Pp 1900Interface names and interface group names, and 1901.Ar self 1902can have modifiers appended: 1903.Pp 1904.Bl -tag -width xxxxxxxxxxxx -compact 1905.It Ar :network 1906Translates to the network(s) attached to the interface. 1907.It Ar :broadcast 1908Translates to the interface's broadcast address(es). 1909.It Ar :peer 1910Translates to the point-to-point interface's peer address(es). 1911.It Ar :0 1912Do not include interface aliases. 1913.El 1914.Pp 1915Host names may also have the 1916.Ar :0 1917option appended to restrict the name resolution to the first of each 1918v4 and non-link-local v6 address found. 1919.Pp 1920Host name resolution and interface to address translation are done at 1921ruleset load-time. 1922When the address of an interface (or host name) changes (under DHCP or PPP, 1923for instance), the ruleset must be reloaded for the change to be reflected 1924in the kernel. 1925Surrounding the interface name (and optional modifiers) in parentheses 1926changes this behaviour. 1927When the interface name is surrounded by parentheses, the rule is 1928automatically updated whenever the interface changes its address. 1929The ruleset does not need to be reloaded. 1930This is especially useful with 1931.Ar nat . 1932.Pp 1933Ports can be specified either by number or by name. 1934For example, port 80 can be specified as 1935.Em www . 1936For a list of all port name to number mappings used by 1937.Xr pfctl 8 , 1938see the file 1939.Pa /etc/services . 1940.Pp 1941Ports and ranges of ports are specified by using these operators: 1942.Bd -literal -offset indent 1943= (equal) 1944!= (unequal) 1945< (less than) 1946<= (less than or equal) 1947> (greater than) 1948>= (greater than or equal) 1949: (range including boundaries) 1950>< (range excluding boundaries) 1951<> (except range) 1952.Ed 1953.Pp 1954.Sq >< , 1955.Sq <> 1956and 1957.Sq \&: 1958are binary operators (they take two arguments). 1959For instance: 1960.Bl -tag -width Fl 1961.It Ar port 2000:2004 1962means 1963.Sq all ports >= 2000 and <= 2004 , 1964hence ports 2000, 2001, 2002, 2003 and 2004. 1965.It Ar port 2000 >< 2004 1966means 1967.Sq all ports > 2000 and < 2004 , 1968hence ports 2001, 2002 and 2003. 1969.It Ar port 2000 <> 2004 1970means 1971.Sq all ports < 2000 or > 2004 , 1972hence ports 1-1999 and 2005-65535. 1973.El 1974.Pp 1975The operating system of the source host can be specified in the case of TCP 1976rules with the 1977.Ar OS 1978modifier. 1979See the 1980.Sx OPERATING SYSTEM FINGERPRINTING 1981section for more information. 1982.Pp 1983The host, port and OS specifications are optional, as in the following examples: 1984.Bd -literal -offset indent 1985pass in all 1986pass in from any to any 1987pass in proto tcp from any port < 1024 to any 1988pass in proto tcp from any to any port 25 1989pass in proto tcp from 10.0.0.0/8 port >= 1024 \e 1990 to ! 10.1.2.3 port != ssh 1991pass in proto tcp from any os "OpenBSD" 1992.Ed 1993.It Ar all 1994This is equivalent to "from any to any". 1995.It Ar group Aq Ar group 1996Similar to 1997.Ar user , 1998this rule only applies to packets of sockets owned by the specified group. 1999.It Ar user Aq Ar user 2000This rule only applies to packets of sockets owned by the specified user. 2001For outgoing connections initiated from the firewall, this is the user 2002that opened the connection. 2003For incoming connections to the firewall itself, this is the user that 2004listens on the destination port. 2005For forwarded connections, where the firewall is not a connection endpoint, 2006the user and group are 2007.Em unknown . 2008.Pp 2009All packets, both outgoing and incoming, of one connection are associated 2010with the same user and group. 2011Only TCP and UDP packets can be associated with users; for other protocols 2012these parameters are ignored. 2013.Pp 2014User and group refer to the effective (as opposed to the real) IDs, in 2015case the socket is created by a setuid/setgid process. 2016User and group IDs are stored when a socket is created; 2017when a process creates a listening socket as root (for instance, by 2018binding to a privileged port) and subsequently changes to another 2019user ID (to drop privileges), the credentials will remain root. 2020.Pp 2021User and group IDs can be specified as either numbers or names. 2022The syntax is similar to the one for ports. 2023The value 2024.Em unknown 2025matches packets of forwarded connections. 2026.Em unknown 2027can only be used with the operators 2028.Cm = 2029and 2030.Cm != . 2031Other constructs like 2032.Cm user \*(Ge unknown 2033are invalid. 2034Forwarded packets with unknown user and group ID match only rules 2035that explicitly compare against 2036.Em unknown 2037with the operators 2038.Cm = 2039or 2040.Cm != . 2041For instance 2042.Cm user \*(Ge 0 2043does not match forwarded packets. 2044The following example allows only selected users to open outgoing 2045connections: 2046.Bd -literal -offset indent 2047block out proto { tcp, udp } all 2048pass out proto { tcp, udp } all user { < 1000, dhartmei } 2049.Ed 2050.Pp 2051The example below permits users with uid between 1000 and 1500 2052to open connections: 2053.Bd -literal -offset indent 2054block out proto tcp all 2055pass out proto tcp from self user { 999 >< 1501 } 2056.Ed 2057.Pp 2058The 2059.Sq \&: 2060operator, which works for port number matching, does not work for 2061.Cm user 2062and 2063.Cm group 2064match. 2065.It Xo Ar flags Aq Ar a 2066.Pf / Ns Aq Ar b 2067.No \*(Ba / Ns Aq Ar b 2068.No \*(Ba any 2069.Xc 2070This rule only applies to TCP packets that have the flags 2071.Aq Ar a 2072set out of set 2073.Aq Ar b . 2074Flags not specified in 2075.Aq Ar b 2076are ignored. 2077For stateful connections, the default is 2078.Ar flags S/SA . 2079To indicate that flags should not be checked at all, specify 2080.Ar flags any . 2081The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R. 2082.Bl -tag -width Fl 2083.It Ar flags S/S 2084Flag SYN is set. 2085The other flags are ignored. 2086.It Ar flags S/SA 2087This is the default setting for stateful connections. 2088Out of SYN and ACK, exactly SYN may be set. 2089SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not. 2090This is more restrictive than the previous example. 2091.It Ar flags /SFRA 2092If the first set is not specified, it defaults to none. 2093All of SYN, FIN, RST and ACK must be unset. 2094.El 2095.Pp 2096Because 2097.Ar flags S/SA 2098is applied by default (unless 2099.Ar no state 2100is specified), only the initial SYN packet of a TCP handshake will create 2101a state for a TCP connection. 2102It is possible to be less restrictive, and allow state creation from 2103intermediate 2104.Pq non-SYN 2105packets, by specifying 2106.Ar flags any . 2107This will cause 2108.Xr pf 4 2109to synchronize to existing connections, for instance 2110if one flushes the state table. 2111However, states created from such intermediate packets may be missing 2112connection details such as the TCP window scaling factor. 2113States which modify the packet flow, such as those affected by 2114.Ar af-to , 2115.Ar nat , 2116.Ar binat or 2117.Ar rdr 2118rules, 2119.Ar modulate No or Ar synproxy state 2120options, or scrubbed with 2121.Ar reassemble tcp 2122will also not be recoverable from intermediate packets. 2123Such connections will stall and time out. 2124.It Xo Ar icmp-type Aq Ar type 2125.Ar Op code Aq Ar code 2126.Xc 2127.It Xo Ar icmp6-type Aq Ar type 2128.Ar Op code Aq Ar code 2129.Xc 2130This rule only applies to ICMP or ICMPv6 packets with the specified type 2131and code. 2132Text names for ICMP types and codes are listed in 2133.Xr icmp 4 2134and 2135.Xr icmp6 4 . 2136This parameter is only valid for rules that cover protocols ICMP or 2137ICMP6. 2138The protocol and the ICMP type indicator 2139.Po 2140.Ar icmp-type 2141or 2142.Ar icmp6-type 2143.Pc 2144must match. 2145.It Xo Ar tos Aq Ar string 2146.No \*(Ba Aq Ar number 2147.Xc 2148This rule applies to packets with the specified 2149.Em TOS 2150bits set. 2151.Em TOS 2152may be 2153given as one of 2154.Ar critical , 2155.Ar inetcontrol , 2156.Ar lowdelay , 2157.Ar netcontrol , 2158.Ar throughput , 2159.Ar reliability , 2160or one of the DiffServ Code Points: 2161.Ar ef , 2162.Ar va , 2163.Ar af11 No ... Ar af43 , 2164.Ar cs0 No ... Ar cs7 ; 2165or as either hex or decimal. 2166.Pp 2167For example, the following rules are identical: 2168.Bd -literal -offset indent 2169pass all tos lowdelay 2170pass all tos 0x10 2171pass all tos 16 2172.Ed 2173.It Ar allow-opts 2174By default, packets with IPv4 options or IPv6 hop-by-hop or destination 2175options header are blocked. 2176When 2177.Ar allow-opts 2178is specified for a 2179.Ar pass 2180rule, packets that pass the filter based on that rule (last matching) 2181do so even if they contain options. 2182For packets that match state, the rule that initially created the 2183state is used. 2184The implicit 2185.Ar pass 2186rule, that is used when a packet does not match 2187any rules, does not allow IP options or option headers. 2188Note that IPv6 packets with type 0 routing headers are always dropped. 2189.It Ar label Aq Ar string 2190Adds a label (name) to the rule, which can be used to identify the rule. 2191For instance, 2192pfctl -s labels 2193shows per-rule statistics for rules that have labels. 2194.Pp 2195The following macros can be used in labels: 2196.Pp 2197.Bl -tag -width $srcaddr -compact -offset indent 2198.It Ar $if 2199The interface. 2200.It Ar $srcaddr 2201The source IP address. 2202.It Ar $dstaddr 2203The destination IP address. 2204.It Ar $srcport 2205The source port specification. 2206.It Ar $dstport 2207The destination port specification. 2208.It Ar $proto 2209The protocol name. 2210.It Ar $nr 2211The rule number. 2212.El 2213.Pp 2214For example: 2215.Bd -literal -offset indent 2216ips = \&"{ 1.2.3.4, 1.2.3.5 }\&" 2217pass in proto tcp from any to $ips \e 2218 port > 1023 label \&"$dstaddr:$dstport\&" 2219.Ed 2220.Pp 2221expands to 2222.Bd -literal -offset indent 2223pass in inet proto tcp from any to 1.2.3.4 \e 2224 port > 1023 label \&"1.2.3.4:>1023\&" 2225pass in inet proto tcp from any to 1.2.3.5 \e 2226 port > 1023 label \&"1.2.3.5:>1023\&" 2227.Ed 2228.Pp 2229The macro expansion for the 2230.Ar label 2231directive occurs only at configuration file parse time, not during runtime. 2232.It Ar ridentifier Aq Ar number 2233Add an identifier (number) to the rule, which can be used to correlate the rule 2234to pflog entries, even after ruleset updates. 2235.It Cm max-pkt-rate Ar number Ns / Ns Ar seconds 2236Measure the rate of packets matching the rule and states created by it. 2237When the specified rate is exceeded, the rule stops matching. 2238Only packets in the direction in which the state was created are considered, 2239so that typically requests are counted and replies are not. 2240For example, 2241to pass up to 100 ICMP packets per 10 seconds: 2242.Bd -literal -offset indent 2243block in proto icmp 2244pass in proto icmp max-pkt-rate 100/10 2245.Ed 2246.Pp 2247When the rate is exceeded, all ICMP is blocked until the rate falls below 2248100 per 10 seconds again. 2249.Pp 2250.It Ar max-pkt-size Aq Ar number 2251Limit each packet to be no more than the specified number of bytes. 2252This includes the IP header, but not any layer 2 header. 2253.It Xo Ar queue Aq Ar queue 2254.No \*(Ba ( Aq Ar queue , 2255.Aq Ar queue ) 2256.Xc 2257Packets matching this rule will be assigned to the specified queue. 2258If two queues are given, packets which have a 2259.Em TOS 2260of 2261.Em lowdelay 2262and TCP ACKs with no data payload will be assigned to the second one. 2263See 2264.Sx QUEUEING 2265for setup details. 2266.Pp 2267For example: 2268.Bd -literal -offset indent 2269pass in proto tcp to port 25 queue mail 2270pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio) 2271.Ed 2272.It Cm set prio Ar priority | Pq Ar priority , priority 2273Packets matching this rule will be assigned a specific queueing priority. 2274Priorities are assigned as integers 0 through 7. 2275If the packet is transmitted on a 2276.Xr vlan 4 2277interface, the queueing priority will be written as the priority 2278code point in the 802.1Q VLAN header. 2279If two priorities are given, TCP ACKs with no data payload and packets 2280which have a TOS of 2281.Cm lowdelay 2282will be assigned to the second one. 2283.Pp 2284For example: 2285.Bd -literal -offset indent 2286pass in proto tcp to port 25 set prio 2 2287pass in proto tcp to port 22 set prio (2, 5) 2288.Ed 2289.It Oo Cm \&! Oc Ns Cm received-on Ar interface 2290Only match packets which were received on the specified 2291.Ar interface 2292(or interface group). 2293.Ar any 2294will match any existing interface except loopback ones. 2295.It Ar tag Aq Ar string 2296Packets matching this rule will be tagged with the 2297specified string. 2298The tag acts as an internal marker that can be used to 2299identify these packets later on. 2300This can be used, for example, to provide trust between 2301interfaces and to determine if packets have been 2302processed by translation rules. 2303Tags are 2304.Qq sticky , 2305meaning that the packet will be tagged even if the rule 2306is not the last matching rule. 2307Further matching rules can replace the tag with a 2308new one but will not remove a previously applied tag. 2309A packet is only ever assigned one tag at a time. 2310Packet tagging can be done during 2311.Ar nat , 2312.Ar rdr , 2313.Ar binat 2314or 2315.Ar ether 2316rules in addition to filter rules. 2317Tags take the same macros as labels (see above). 2318.It Ar tagged Aq Ar string 2319Used with filter, translation or scrub rules 2320to specify that packets must already 2321be tagged with the given tag in order to match the rule. 2322.It Ar rtable Aq Ar number 2323Used to select an alternate routing table for the routing lookup. 2324Only effective before the route lookup happened, i.e. when filtering inbound. 2325.It Xo Ar divert-to Aq Ar host 2326.Ar port Aq Ar port 2327.Xc 2328Used to 2329.Xr divert 4 2330packets to the given divert 2331.Ar port . 2332Historically 2333.Ox pf has another meaning for this, and 2334.Fx pf uses 2335this syntax to support 2336.Xr divert 4 instead. Hence, 2337.Ar host 2338has no meaning and can be set to anything like 127.0.0.1. 2339If a packet is re-injected and does not change direction then it will not be 2340re-diverted. 2341.It Ar divert-reply 2342It has no meaning in 2343.Fx pf . 2344.It Ar probability Aq Ar number 2345A probability attribute can be attached to a rule, with a value set between 23460 and 1, bounds not included. 2347In that case, the rule will be honoured using the given probability value 2348only. 2349For example, the following rule will drop 20% of incoming ICMP packets: 2350.Bd -literal -offset indent 2351block in proto icmp probability 20% 2352.Ed 2353.It Ar prio Aq Ar number 2354Only match packets which have the given queueing priority assigned. 2355.El 2356.Sh ROUTING 2357If a packet matches a rule with a route option set, the packet filter will 2358route the packet according to the type of route option. 2359When such a rule creates state, the route option is also applied to all 2360packets matching the same connection. 2361.Bl -tag -width xxxx 2362.It Ar route-to 2363The 2364.Ar route-to 2365option routes the packet to the specified interface with an optional address 2366for the next hop. 2367When a 2368.Ar route-to 2369rule creates state, only packets that pass in the same direction as the 2370filter rule specifies will be routed in this way. 2371Packets passing in the opposite direction (replies) are not affected 2372and are routed normally. 2373.It Ar reply-to 2374The 2375.Ar reply-to 2376option is similar to 2377.Ar route-to , 2378but routes packets that pass in the opposite direction (replies) to the 2379specified interface. 2380Opposite direction is only defined in the context of a state entry, and 2381.Ar reply-to 2382is useful only in rules that create state. 2383It can be used on systems with multiple external connections to 2384route all outgoing packets of a connection through the interface 2385the incoming connection arrived through (symmetric routing enforcement). 2386.It Ar dup-to 2387The 2388.Ar dup-to 2389option creates a duplicate of the packet and routes it like 2390.Ar route-to . 2391The original packet gets routed as it normally would. 2392.El 2393.Sh POOL OPTIONS 2394For 2395.Ar nat 2396and 2397.Ar rdr 2398rules, (as well as for the 2399.Ar route-to , 2400.Ar reply-to 2401and 2402.Ar dup-to 2403rule options) for which there is a single redirection address which has a 2404subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP 2405address), a variety of different methods for assigning this address can be 2406used: 2407.Bl -tag -width xxxx 2408.It Ar bitmask 2409The 2410.Ar bitmask 2411option applies the network portion of the redirection address to the address 2412to be modified (source with 2413.Ar nat , 2414destination with 2415.Ar rdr ) . 2416.It Ar random 2417The 2418.Ar random 2419option selects an address at random within the defined block of addresses. 2420.It Ar source-hash 2421The 2422.Ar source-hash 2423option uses a hash of the source address to determine the redirection address, 2424ensuring that the redirection address is always the same for a given source. 2425An optional key can be specified after this keyword either in hex or as a 2426string; by default 2427.Xr pfctl 8 2428randomly generates a key for source-hash every time the 2429ruleset is reloaded. 2430.It Ar round-robin 2431The 2432.Ar round-robin 2433option loops through the redirection address(es). 2434.Pp 2435When more than one redirection address is specified, 2436.Ar bitmask 2437is not permitted as a pool type. 2438.It Ar static-port 2439With 2440.Ar nat 2441rules, the 2442.Ar static-port 2443option prevents 2444.Xr pf 4 2445from modifying the source port on TCP and UDP packets. 2446.It Xo Ar map-e-portset Aq Ar psid-offset 2447.No / Aq Ar psid-len 2448.No / Aq Ar psid 2449.Xc 2450With 2451.Ar nat 2452rules, the 2453.Ar map-e-portset 2454option enables the source port translation of MAP-E (RFC 7597) Customer Edge. 2455In order to make the host act as a MAP-E Customer Edge, setting up a tunneling 2456interface and pass rules for encapsulated packets are required in addition 2457to the map-e-portset nat rule. 2458.Pp 2459For example: 2460.Bd -literal -offset indent 2461nat on $gif_mape_if from $int_if:network to any \e 2462 -> $ipv4_mape_src map-e-portset 6/8/0x34 2463.Ed 2464.Pp 2465sets PSID offset 6, PSID length 8, PSID 0x34. 2466.It Ar endpoint-independent 2467With 2468.Ar nat 2469rules, the 2470.Ar endpoint-independent 2471option caues 2472.Xr pf 4 2473to always map connections from a UDP source address and port to the same 2474NAT address and port. 2475This feature implements "full-cone" NAT behavior. 2476.El 2477.Pp 2478Additionally, the 2479.Ar sticky-address 2480option can be specified to help ensure that multiple connections from the 2481same source are mapped to the same redirection address. 2482This option can be used with the 2483.Ar random 2484and 2485.Ar round-robin 2486pool options. 2487Note that by default these associations are destroyed as soon as there are 2488no longer states which refer to them; in order to make the mappings last 2489beyond the lifetime of the states, increase the global options with 2490.Ar set timeout src.track . 2491See 2492.Sx STATEFUL TRACKING OPTIONS 2493for more ways to control the source tracking. 2494.Sh STATE MODULATION 2495Much of the security derived from TCP is attributable to how well the 2496initial sequence numbers (ISNs) are chosen. 2497Some popular stack implementations choose 2498.Em very 2499poor ISNs and thus are normally susceptible to ISN prediction exploits. 2500By applying a 2501.Ar modulate state 2502rule to a TCP connection, 2503.Xr pf 4 2504will create a high quality random sequence number for each connection 2505endpoint. 2506.Pp 2507The 2508.Ar modulate state 2509directive implicitly keeps state on the rule and is 2510only applicable to TCP connections. 2511.Pp 2512For instance: 2513.Bd -literal -offset indent 2514block all 2515pass out proto tcp from any to any modulate state 2516pass in proto tcp from any to any port 25 flags S/SFRA modulate state 2517.Ed 2518.Pp 2519Note that modulated connections will not recover when the state table 2520is lost (firewall reboot, flushing the state table, etc...). 2521.Xr pf 4 2522will not be able to infer a connection again after the state table flushes 2523the connection's modulator. 2524When the state is lost, the connection may be left dangling until the 2525respective endpoints time out the connection. 2526It is possible on a fast local network for the endpoints to start an ACK 2527storm while trying to resynchronize after the loss of the modulator. 2528The default 2529.Ar flags 2530settings (or a more strict equivalent) should be used on 2531.Ar modulate state 2532rules to prevent ACK storms. 2533.Pp 2534Note that alternative methods are available 2535to prevent loss of the state table 2536and allow for firewall failover. 2537See 2538.Xr carp 4 2539and 2540.Xr pfsync 4 2541for further information. 2542.Sh SYN PROXY 2543By default, 2544.Xr pf 4 2545passes packets that are part of a 2546.Xr tcp 4 2547handshake between the endpoints. 2548The 2549.Ar synproxy state 2550option can be used to cause 2551.Xr pf 4 2552itself to complete the handshake with the active endpoint, perform a handshake 2553with the passive endpoint, and then forward packets between the endpoints. 2554.Pp 2555No packets are sent to the passive endpoint before the active endpoint has 2556completed the handshake, hence so-called SYN floods with spoofed source 2557addresses will not reach the passive endpoint, as the sender can't complete the 2558handshake. 2559.Pp 2560The proxy is transparent to both endpoints, they each see a single 2561connection from/to the other endpoint. 2562.Xr pf 4 2563chooses random initial sequence numbers for both handshakes. 2564Once the handshakes are completed, the sequence number modulators 2565(see previous section) are used to translate further packets of the 2566connection. 2567.Ar synproxy state 2568includes 2569.Ar modulate state . 2570.Pp 2571Rules with 2572.Ar synproxy 2573will not work if 2574.Xr pf 4 2575operates on a 2576.Xr bridge 4 . 2577Also they act on incoming SYN packets only. 2578.Pp 2579Example: 2580.Bd -literal -offset indent 2581pass in proto tcp from any to any port www synproxy state 2582.Ed 2583.Sh STATEFUL TRACKING OPTIONS 2584A number of options related to stateful tracking can be applied on a 2585per-rule basis. 2586.Ar keep state , 2587.Ar modulate state 2588and 2589.Ar synproxy state 2590support these options, and 2591.Ar keep state 2592must be specified explicitly to apply options to a rule. 2593.Pp 2594.Bl -tag -width xxxx -compact 2595.It Ar max Aq Ar number 2596Limits the number of concurrent states the rule may create. 2597When this limit is reached, further packets that would create 2598state are dropped until existing states time out. 2599.It Ar no-sync 2600Prevent state changes for states created by this rule from appearing on the 2601.Xr pfsync 4 2602interface. 2603.It Xo Aq Ar timeout 2604.Aq Ar seconds 2605.Xc 2606Changes the timeout values used for states created by this rule. 2607For a list of all valid timeout names, see 2608.Sx OPTIONS 2609above. 2610.It Ar sloppy 2611Uses a sloppy TCP connection tracker that does not check sequence 2612numbers at all, which makes insertion and ICMP teardown attacks way 2613easier. 2614This is intended to be used in situations where one does not see all 2615packets of a connection, e.g. in asymmetric routing situations. 2616Cannot be used with modulate or synproxy state. 2617.It Ar pflow 2618States created by this rule are exported on the 2619.Xr pflow 4 2620interface. 2621.It Ar allow-related 2622Automatically allow connections related to this one, regardless of rules that 2623might otherwise affect them. 2624This currently only applies to SCTP multihomed connection. 2625.El 2626.Pp 2627Multiple options can be specified, separated by commas: 2628.Bd -literal -offset indent 2629pass in proto tcp from any to any \e 2630 port www keep state \e 2631 (max 100, source-track rule, max-src-nodes 75, \e 2632 max-src-states 3, tcp.established 60, tcp.closing 5) 2633.Ed 2634.Pp 2635When the 2636.Ar source-track 2637keyword is specified, the number of states per source IP is tracked. 2638.Pp 2639.Bl -tag -width xxxx -compact 2640.It Ar source-track rule 2641The maximum number of states created by this rule is limited by the rule's 2642.Ar max-src-nodes 2643and 2644.Ar max-src-states 2645options. 2646Only state entries created by this particular rule count toward the rule's 2647limits. 2648.It Ar source-track global 2649The number of states created by all rules that use this option is limited. 2650Each rule can specify different 2651.Ar max-src-nodes 2652and 2653.Ar max-src-states 2654options, however state entries created by any participating rule count towards 2655each individual rule's limits. 2656.El 2657.Pp 2658The following limits can be set: 2659.Pp 2660.Bl -tag -width xxxx -compact 2661.It Ar max-src-nodes Aq Ar number 2662Limits the maximum number of source addresses which can simultaneously 2663have state table entries. 2664.It Ar max-src-states Aq Ar number 2665Limits the maximum number of simultaneous state entries that a single 2666source address can create with this rule. 2667.El 2668.Pp 2669For stateful TCP connections, limits on established connections (connections 2670which have completed the TCP 3-way handshake) can also be enforced 2671per source IP. 2672.Pp 2673.Bl -tag -width xxxx -compact 2674.It Ar max-src-conn Aq Ar number 2675Limits the maximum number of simultaneous TCP connections which have 2676completed the 3-way handshake that a single host can make. 2677.It Xo Ar max-src-conn-rate Aq Ar number 2678.No / Aq Ar seconds 2679.Xc 2680Limit the rate of new connections over a time interval. 2681The connection rate is an approximation calculated as a moving average. 2682.El 2683.Pp 2684When one of these limits is reached, further packets that would create 2685state are dropped until existing states time out. 2686.Pp 2687Because the 3-way handshake ensures that the source address is not being 2688spoofed, more aggressive action can be taken based on these limits. 2689With the 2690.Ar overload Aq Ar table 2691state option, source IP addresses which hit either of the limits on 2692established connections will be added to the named table. 2693This table can be used in the ruleset to block further activity from 2694the offending host, redirect it to a tarpit process, or restrict its 2695bandwidth. 2696.Pp 2697The optional 2698.Ar flush 2699keyword kills all states created by the matching rule which originate 2700from the host which exceeds these limits. 2701The 2702.Ar global 2703modifier to the flush command kills all states originating from the 2704offending host, regardless of which rule created the state. 2705.Pp 2706For example, the following rules will protect the webserver against 2707hosts making more than 100 connections in 10 seconds. 2708Any host which connects faster than this rate will have its address added 2709to the 2710.Aq bad_hosts 2711table and have all states originating from it flushed. 2712Any new packets arriving from this host will be dropped unconditionally 2713by the block rule. 2714.Bd -literal -offset indent 2715block quick from <bad_hosts> 2716pass in on $ext_if proto tcp to $webserver port www keep state \e 2717 (max-src-conn-rate 100/10, overload <bad_hosts> flush global) 2718.Ed 2719.Sh OPERATING SYSTEM FINGERPRINTING 2720Passive OS Fingerprinting is a mechanism to inspect nuances of a TCP 2721connection's initial SYN packet and guess at the host's operating system. 2722Unfortunately these nuances are easily spoofed by an attacker so the 2723fingerprint is not useful in making security decisions. 2724But the fingerprint is typically accurate enough to make policy decisions 2725upon. 2726.Pp 2727The fingerprints may be specified by operating system class, by 2728version, or by subtype/patchlevel. 2729The class of an operating system is typically the vendor or genre 2730and would be 2731.Ox 2732for the 2733.Xr pf 4 2734firewall itself. 2735The version of the oldest available 2736.Ox 2737release on the main FTP site 2738would be 2.6 and the fingerprint would be written 2739.Pp 2740.Dl \&"OpenBSD 2.6\&" 2741.Pp 2742The subtype of an operating system is typically used to describe the 2743patchlevel if that patch led to changes in the TCP stack behavior. 2744In the case of 2745.Ox , 2746the only subtype is for a fingerprint that was 2747normalized by the 2748.Ar no-df 2749scrub option and would be specified as 2750.Pp 2751.Dl \&"OpenBSD 3.3 no-df\&" 2752.Pp 2753Fingerprints for most popular operating systems are provided by 2754.Xr pf.os 5 . 2755Once 2756.Xr pf 4 2757is running, a complete list of known operating system fingerprints may 2758be listed by running: 2759.Pp 2760.Dl # pfctl -so 2761.Pp 2762Filter rules can enforce policy at any level of operating system specification 2763assuming a fingerprint is present. 2764Policy could limit traffic to approved operating systems or even ban traffic 2765from hosts that aren't at the latest service pack. 2766.Pp 2767The 2768.Ar unknown 2769class can also be used as the fingerprint which will match packets for 2770which no operating system fingerprint is known. 2771.Pp 2772Examples: 2773.Bd -literal -offset indent 2774pass out proto tcp from any os OpenBSD 2775block out proto tcp from any os Doors 2776block out proto tcp from any os "Doors PT" 2777block out proto tcp from any os "Doors PT SP3" 2778block out from any os "unknown" 2779pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" 2780.Ed 2781.Pp 2782Operating system fingerprinting is limited only to the TCP SYN packet. 2783This means that it will not work on other protocols and will not match 2784a currently established connection. 2785.Pp 2786Caveat: operating system fingerprints are occasionally wrong. 2787There are three problems: an attacker can trivially craft packets to 2788appear as any operating system; 2789an operating system patch could change the stack behavior and no fingerprints 2790will match it until the database is updated; 2791and multiple operating systems may have the same fingerprint. 2792.Sh BLOCKING SPOOFED TRAFFIC 2793"Spoofing" is the faking of IP addresses, typically for malicious 2794purposes. 2795The 2796.Ar antispoof 2797directive expands to a set of filter rules which will block all 2798traffic with a source IP from the network(s) directly connected 2799to the specified interface(s) from entering the system through 2800any other interface. 2801.Pp 2802For example, the line 2803.Bd -literal -offset indent 2804antispoof for lo0 2805.Ed 2806.Pp 2807expands to 2808.Bd -literal -offset indent 2809block drop in on ! lo0 inet from 127.0.0.1/8 to any 2810block drop in on ! lo0 inet6 from ::1 to any 2811.Ed 2812.Pp 2813For non-loopback interfaces, there are additional rules to block incoming 2814packets with a source IP address identical to the interface's IP(s). 2815For example, assuming the interface wi0 had an IP address of 10.0.0.1 and a 2816netmask of 255.255.255.0, 2817the line 2818.Bd -literal -offset indent 2819antispoof for wi0 inet 2820.Ed 2821.Pp 2822expands to 2823.Bd -literal -offset indent 2824block drop in on ! wi0 inet from 10.0.0.0/24 to any 2825block drop in inet from 10.0.0.1 to any 2826.Ed 2827.Pp 2828Caveat: Rules created by the 2829.Ar antispoof 2830directive interfere with packets sent over loopback interfaces 2831to local addresses. 2832One should pass these explicitly. 2833.Sh FRAGMENT HANDLING 2834The size of IP datagrams (packets) can be significantly larger than the 2835maximum transmission unit (MTU) of the network. 2836In cases when it is necessary or more efficient to send such large packets, 2837the large packet will be fragmented into many smaller packets that will each 2838fit onto the wire. 2839Unfortunately for a firewalling device, only the first logical fragment will 2840contain the necessary header information for the subprotocol that allows 2841.Xr pf 4 2842to filter on things such as TCP ports or to perform NAT. 2843.Pp 2844Besides the use of 2845.Ar set reassemble 2846option or 2847.Ar scrub 2848rules as described in 2849.Sx TRAFFIC NORMALIZATION 2850above, there are three options for handling fragments in the packet filter. 2851.Pp 2852One alternative is to filter individual fragments with filter rules. 2853If no 2854.Ar scrub 2855rule applies to a fragment or 2856.Ar set reassemble 2857is set to 2858.Cm no 2859, it is passed to the filter. 2860Filter rules with matching IP header parameters decide whether the 2861fragment is passed or blocked, in the same way as complete packets 2862are filtered. 2863Without reassembly, fragments can only be filtered based on IP header 2864fields (source/destination address, protocol), since subprotocol header 2865fields are not available (TCP/UDP port numbers, ICMP code/type). 2866The 2867.Ar fragment 2868option can be used to restrict filter rules to apply only to 2869fragments, but not complete packets. 2870Filter rules without the 2871.Ar fragment 2872option still apply to fragments, if they only specify IP header fields. 2873For instance, the rule 2874.Bd -literal -offset indent 2875pass in proto tcp from any to any port 80 2876.Ed 2877.Pp 2878never applies to a fragment, even if the fragment is part of a TCP 2879packet with destination port 80, because without reassembly this information 2880is not available for each fragment. 2881This also means that fragments cannot create new or match existing 2882state table entries, which makes stateful filtering and address 2883translation (NAT, redirection) for fragments impossible. 2884.Pp 2885It's also possible to reassemble only certain fragments by specifying 2886source or destination addresses or protocols as parameters in 2887.Ar scrub 2888rules. 2889.Pp 2890In most cases, the benefits of reassembly outweigh the additional 2891memory cost, and it's recommended to use 2892.Ar set reassemble 2893option or 2894.Ar scrub 2895rules with the 2896.Ar fragment reassemble 2897modifier to reassemble 2898all fragments. 2899.Pp 2900The memory allocated for fragment caching can be limited using 2901.Xr pfctl 8 . 2902Once this limit is reached, fragments that would have to be cached 2903are dropped until other entries time out. 2904The timeout value can also be adjusted. 2905.Pp 2906When forwarding reassembled IPv6 packets, pf refragments them with 2907the original maximum fragment size. 2908This allows the sender to determine the optimal fragment size by 2909path MTU discovery. 2910.Sh ANCHORS 2911Besides the main ruleset, 2912.Xr pfctl 8 2913can load rulesets into 2914.Ar anchor 2915attachment points. 2916An 2917.Ar anchor 2918is a container that can hold rules, address tables, and other anchors. 2919.Pp 2920An 2921.Ar anchor 2922has a name which specifies the path where 2923.Xr pfctl 8 2924can be used to access the anchor to perform operations on it, such as 2925attaching child anchors to it or loading rules into it. 2926Anchors may be nested, with components separated by 2927.Sq / 2928characters, similar to how file system hierarchies are laid out. 2929The main ruleset is actually the default anchor, so filter and 2930translation rules, for example, may also be contained in any anchor. 2931.Pp 2932An anchor can reference another 2933.Ar anchor 2934attachment point 2935using the following kinds 2936of rules: 2937.Bl -tag -width xxxx 2938.It Ar nat-anchor Aq Ar name 2939Evaluates the 2940.Ar nat 2941rules in the specified 2942.Ar anchor . 2943.It Ar rdr-anchor Aq Ar name 2944Evaluates the 2945.Ar rdr 2946rules in the specified 2947.Ar anchor . 2948.It Ar binat-anchor Aq Ar name 2949Evaluates the 2950.Ar binat 2951rules in the specified 2952.Ar anchor . 2953.It Ar anchor Aq Ar name 2954Evaluates the filter rules in the specified 2955.Ar anchor . 2956.It Xo Ar load anchor 2957.Aq Ar name 2958.Ar from Aq Ar file 2959.Xc 2960Loads the rules from the specified file into the 2961anchor 2962.Ar name . 2963.El 2964.Pp 2965When evaluation of the main ruleset reaches an 2966.Ar anchor 2967rule, 2968.Xr pf 4 2969will proceed to evaluate all rules specified in that anchor. 2970.Pp 2971Matching filter and translation rules marked with the 2972.Ar quick 2973option are final and abort the evaluation of the rules in other 2974anchors and the main ruleset. 2975If the 2976.Ar anchor 2977itself is marked with the 2978.Ar quick 2979option, 2980ruleset evaluation will terminate when the anchor is exited if the packet is 2981matched by any rule within the anchor. 2982.Pp 2983.Ar anchor 2984rules are evaluated relative to the anchor in which they are contained. 2985For example, all 2986.Ar anchor 2987rules specified in the main ruleset will reference anchor 2988attachment points underneath the main ruleset, and 2989.Ar anchor 2990rules specified in a file loaded from a 2991.Ar load anchor 2992rule will be attached under that anchor point. 2993.Pp 2994Rules may be contained in 2995.Ar anchor 2996attachment points which do not contain any rules when the main ruleset 2997is loaded, and later such anchors can be manipulated through 2998.Xr pfctl 8 2999without reloading the main ruleset or other anchors. 3000For example, 3001.Bd -literal -offset indent 3002ext_if = \&"kue0\&" 3003block on $ext_if all 3004anchor spam 3005pass out on $ext_if all 3006pass in on $ext_if proto tcp from any \e 3007 to $ext_if port smtp 3008.Ed 3009.Pp 3010blocks all packets on the external interface by default, then evaluates 3011all rules in the 3012.Ar anchor 3013named "spam", and finally passes all outgoing connections and 3014incoming connections to port 25. 3015.Bd -literal -offset indent 3016# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e 3017 pfctl -a spam -f - 3018.Ed 3019.Pp 3020This loads a single rule into the 3021.Ar anchor , 3022which blocks all packets from a specific address. 3023.Pp 3024The anchor can also be populated by adding a 3025.Ar load anchor 3026rule after the 3027.Ar anchor 3028rule: 3029.Bd -literal -offset indent 3030anchor spam 3031load anchor spam from "/etc/pf-spam.conf" 3032.Ed 3033.Pp 3034When 3035.Xr pfctl 8 3036loads 3037.Nm pf.conf , 3038it will also load all the rules from the file 3039.Pa /etc/pf-spam.conf 3040into the anchor. 3041.Pp 3042Optionally, 3043.Ar anchor 3044rules can specify packet filtering parameters using the same syntax as 3045filter rules. 3046When parameters are used, the 3047.Ar anchor 3048rule is only evaluated for matching packets. 3049This allows conditional evaluation of anchors, like: 3050.Bd -literal -offset indent 3051block on $ext_if all 3052anchor spam proto tcp from any to any port smtp 3053pass out on $ext_if all 3054pass in on $ext_if proto tcp from any to $ext_if port smtp 3055.Ed 3056.Pp 3057The rules inside 3058.Ar anchor 3059spam are only evaluated for 3060.Ar tcp 3061packets with destination port 25. 3062Hence, 3063.Bd -literal -offset indent 3064# echo \&"block in quick from 1.2.3.4 to any" \&| \e 3065 pfctl -a spam -f - 3066.Ed 3067.Pp 3068will only block connections from 1.2.3.4 to port 25. 3069.Pp 3070Anchors may end with the asterisk 3071.Pq Sq * 3072character, which signifies that all anchors attached at that point 3073should be evaluated in the alphabetical ordering of their anchor name. 3074For example, 3075.Bd -literal -offset indent 3076anchor "spam/*" 3077.Ed 3078.Pp 3079will evaluate each rule in each anchor attached to the 3080.Li spam 3081anchor. 3082Note that it will only evaluate anchors that are directly attached to the 3083.Li spam 3084anchor, and will not descend to evaluate anchors recursively. 3085.Pp 3086Since anchors are evaluated relative to the anchor in which they are 3087contained, there is a mechanism for accessing the parent and ancestor 3088anchors of a given anchor. 3089Similar to file system path name resolution, if the sequence 3090.Dq .. 3091appears as an anchor path component, the parent anchor of the current 3092anchor in the path evaluation at that point will become the new current 3093anchor. 3094As an example, consider the following: 3095.Bd -literal -offset indent 3096# echo ' anchor "spam/allowed" ' | pfctl -f - 3097# echo -e ' anchor "../banned" \en pass' | \e 3098 pfctl -a spam/allowed -f - 3099.Ed 3100.Pp 3101Evaluation of the main ruleset will lead into the 3102.Li spam/allowed 3103anchor, which will evaluate the rules in the 3104.Li spam/banned 3105anchor, if any, before finally evaluating the 3106.Ar pass 3107rule. 3108.Pp 3109An 3110.Ar anchor 3111rule can also contain a filter ruleset in a brace-delimited block. 3112In that case, no separate loading of rules into the anchor 3113is required. 3114Brace delimited blocks may contain rules or other brace-delimited blocks. 3115When an anchor is populated this way, the anchor name becomes optional. 3116.Bd -literal -offset indent 3117anchor "external" on $ext_if { 3118 block 3119 anchor out { 3120 pass proto tcp from any to port { 25, 80, 443 } 3121 } 3122 pass in proto tcp to any port 22 3123} 3124.Ed 3125.Pp 3126Since the parser specification for anchor names is a string, any 3127reference to an anchor name containing 3128.Sq / 3129characters will require double quote 3130.Pq Sq \&" 3131characters around the anchor name. 3132.Sh SCTP CONSIDERATIONS 3133.Xr pf 4 3134supports 3135.Xr sctp 4 3136connections. 3137It can match ports, track state and NAT SCTP traffic. 3138However, it will not alter port numbers during nat or rdr translations. 3139Doing so would break SCTP multihoming. 3140.Sh TRANSLATION EXAMPLES 3141This example maps incoming requests on port 80 to port 8080, on 3142which a daemon is running (because, for example, it is not run as root, 3143and therefore lacks permission to bind to port 80). 3144.Bd -literal -offset indent 3145# use a macro for the interface name, so it can be changed easily 3146ext_if = \&"ne3\&" 3147 3148# map daemon on 8080 to appear to be on 80 3149match in on $ext_if proto tcp from any to any port 80 \e 3150 rdr-to 127.0.0.1 port 8080 3151.Ed 3152.Pp 3153If a 3154.Ar pass 3155rule is used with the 3156.Ar quick 3157modifier, packets matching the translation rule are passed without 3158inspecting subsequent filter rules: 3159.Bd -literal -offset indent 3160pass in quick on $ext_if proto tcp from any to any port 80 \e 3161 rdr-to 127.0.0.1 port 8080 3162.Ed 3163.Pp 3164In the example below, vlan12 is configured as 192.168.168.1; 3165the machine translates all packets coming from 192.168.168.0/24 to 204.92.77.111 3166when they are going out any interface except vlan12. 3167This has the net effect of making traffic from the 192.168.168.0/24 3168network appear as though it is the Internet routable address 3169204.92.77.111 to nodes behind any interface on the router except 3170for the nodes on vlan12. 3171(Thus, 192.168.168.1 can talk to the 192.168.168.0/24 nodes.) 3172.Bd -literal -offset indent 3173match out on ! vlan12 from 192.168.168.0/24 to any nat-to 204.92.77.111 3174.Ed 3175.Pp 3176This longer example uses both a NAT and a redirection. 3177The external interface has the address 157.161.48.183. 3178On localhost, we are running 3179.Xr ftp-proxy 8 , 3180waiting for FTP sessions to be redirected to it. 3181The three mandatory anchors for 3182.Xr ftp-proxy 8 3183are omitted from this example; see the 3184.Xr ftp-proxy 8 3185manpage. 3186.Bd -literal -offset indent 3187# NAT 3188# Translate outgoing packets' source addresses (any protocol). 3189# In this case, any address but the gateway's external address is mapped. 3190pass out on $ext_if inet from ! ($ext_if) to any nat-to ($ext_if) 3191 3192# NAT PROXYING 3193# Map outgoing packets' source port to an assigned proxy port instead of 3194# an arbitrary port. 3195# In this case, proxy outgoing isakmp with port 500 on the gateway. 3196pass out on $ext_if inet proto udp from any port = isakmp to any \e 3197 nat-to ($ext_if) port 500 3198 3199# BINAT 3200# Translate outgoing packets' source address (any protocol). 3201# Translate incoming packets' destination address to an internal machine 3202# (bidirectional). 3203pass on $ext_if from 10.1.2.150 to any binat-to $ext_if 3204 3205# Translate packets arriving on $peer_if addressed to 172.22.16.0/20 3206# to the corresponding address in 172.21.16.0/20 (bidirectional). 3207pass on $peer_if from 172.21.16.0/20 to any binat-to 172.22.16.0/20 3208 3209# RDR 3210# Translate incoming packets' destination addresses. 3211# As an example, redirect a TCP and UDP port to an internal machine. 3212pass in on $ext_if inet proto tcp from any to ($ext_if) port 8080 \e 3213 rdr-to 10.1.2.151 port 22 3214pass in on $ext_if inet proto udp from any to ($ext_if) port 8080 \e 3215 rdr-to 10.1.2.151 port 53 3216 3217# RDR 3218# Translate outgoing ftp control connections to send them to localhost 3219# for proxying with ftp-proxy(8) running on port 8021. 3220pass in on $int_if proto tcp from any to any port 21 \e 3221 rdr-to 127.0.0.1 port 8021 3222.Ed 3223.Pp 3224In this example, a NAT gateway is set up to translate internal addresses 3225using a pool of public addresses (192.0.2.16/28) and to redirect 3226incoming web server connections to a group of web servers on the internal 3227network. 3228.Bd -literal -offset indent 3229# NAT LOAD BALANCE 3230# Translate outgoing packets' source addresses using an address pool. 3231# A given source address is always translated to the same pool address by 3232# using the source-hash keyword. 3233pass out on $ext_if inet from any to any nat-to 192.0.2.16/28 source-hash 3234 3235# RDR ROUND ROBIN 3236# Translate incoming web server connections to a group of web servers on 3237# the internal network. 3238pass in on $ext_if proto tcp from any to any port 80 \e 3239 rdr-to { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin 3240.Ed 3241.Sh COMPATIBILITY TRANSLATION EXAMPLES 3242In the example below, the machine sits between a fake internal 144.19.74.* 3243network, and a routable external IP of 204.92.77.100. 3244The 3245.Ar no nat 3246rule excludes protocol AH from being translated. 3247.Bd -literal -offset indent 3248# NAT 3249no nat on $ext_if proto ah from 144.19.74.0/24 to any 3250nat on $ext_if from 144.19.74.0/24 to any -> 204.92.77.100 3251.Ed 3252.Pp 3253In the example below, packets bound for one specific server, as well as those 3254generated by the sysadmins are not proxied; all other connections are. 3255.Bd -literal -offset indent 3256# RDR 3257no rdr on $int_if proto { tcp, udp } from any to $server port 80 3258no rdr on $int_if proto { tcp, udp } from $sysadmins to any port 80 3259rdr on $int_if proto { tcp, udp } from any to any port 80 \e 3260 -> 127.0.0.1 port 80 3261.Ed 3262.Sh FILTER EXAMPLES 3263.Bd -literal -offset indent 3264# The external interface is kue0 3265# (157.161.48.183, the only routable address) 3266# and the private network is 10.0.0.0/8, for which we are doing NAT. 3267 3268# Reassemble incoming traffic 3269set reassemble yes 3270 3271# use a macro for the interface name, so it can be changed easily 3272ext_if = \&"kue0\&" 3273 3274# block and log everything by default 3275block return log on $ext_if all 3276 3277# block anything coming from source we have no back routes for 3278block in from no-route to any 3279 3280# block packets whose ingress interface does not match the one in 3281# the route back to their source address 3282block in from urpf-failed to any 3283 3284# block and log outgoing packets that do not have our address as source, 3285# they are either spoofed or something is misconfigured (NAT disabled, 3286# for instance), we want to be nice and do not send out garbage. 3287block out log quick on $ext_if from ! 157.161.48.183 to any 3288 3289# silently drop broadcasts (cable modem noise) 3290block in quick on $ext_if from any to 255.255.255.255 3291 3292# block and log incoming packets from reserved address space and invalid 3293# addresses, they are either spoofed or misconfigured, we cannot reply to 3294# them anyway (hence, no return-rst). 3295block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e 3296 192.168.0.0/16, 255.255.255.255/32 } to any 3297 3298# ICMP 3299 3300# pass out/in certain ICMP queries and keep state (ping) 3301# state matching is done on host addresses and ICMP id (not type/code), 3302# so replies (like 0/0 for 8/0) will match queries 3303# ICMP error messages (which always refer to a TCP/UDP packet) are 3304# handled by the TCP/UDP states 3305pass on $ext_if inet proto icmp all icmp-type 8 code 0 3306 3307# UDP 3308 3309# pass out all UDP connections and keep state 3310pass out on $ext_if proto udp all 3311 3312# pass in certain UDP connections and keep state (DNS) 3313pass in on $ext_if proto udp from any to any port domain 3314 3315# TCP 3316 3317# pass out all TCP connections and modulate state 3318pass out on $ext_if proto tcp all modulate state 3319 3320# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT) 3321pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e 3322 auth } 3323 3324# Do not allow Windows 9x SMTP connections since they are typically 3325# a viral worm. Alternately we could limit these OSes to 1 connection each. 3326block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e 3327 to any port smtp 3328 3329# IPv6 3330# pass in/out all IPv6 traffic: note that we have to enable this in two 3331# different ways, on both our physical interface and our tunnel 3332pass quick on gif0 inet6 3333pass quick on $ext_if proto ipv6 3334 3335# Packet Tagging 3336 3337# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is 3338# being done on $ext_if for all outgoing packets. tag packets in on 3339# $int_if and pass those tagged packets out on $ext_if. all other 3340# outgoing packets (i.e., packets from the wireless network) are only 3341# permitted to access port 80. 3342 3343pass in on $int_if from any to any tag INTNET 3344pass in on $wifi_if from any to any 3345 3346block out on $ext_if from any to any 3347pass out quick on $ext_if tagged INTNET 3348pass out on $ext_if proto tcp from any to any port 80 3349 3350# tag incoming packets as they are redirected to spamd(8). use the tag 3351# to pass those packets through the packet filter. 3352 3353rdr on $ext_if inet proto tcp from <spammers> to port smtp \e 3354 tag SPAMD -> 127.0.0.1 port spamd 3355 3356block in on $ext_if 3357pass in on $ext_if inet proto tcp tagged SPAMD 3358.Ed 3359.Pp 3360In the example below, a router handling both address families 3361translates an internal IPv4 subnet to IPv6 using the well-known 336264:ff9b::/96 prefix: 3363.Bd -literal -offset 4n 3364pass in on $v4_if inet af-to inet6 from ($v6_if) to 64:ff9b::/96 3365.Ed 3366.Pp 3367Paired with the example above, the example below can be used on 3368another router handling both address families to translate back 3369to IPv4: 3370.Bd -literal -offset 4n 3371pass in on $v6_if inet6 to 64:ff9b::/96 af-to inet from ($v4_if) 3372.Ed 3373.Sh GRAMMAR 3374Syntax for 3375.Nm 3376in BNF: 3377.Bd -literal 3378line = ( option | ether-rule | pf-rule | nat-rule | binat-rule | 3379 rdr-rule | antispoof-rule | altq-rule | queue-rule | 3380 trans-anchors | anchor-rule | anchor-close | load-anchor | 3381 table-rule | include ) 3382 3383option = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] | 3384 [ "ruleset-optimization" [ "none" | "basic" | "profile" ]] | 3385 [ "optimization" [ "default" | "normal" | 3386 "high-latency" | "satellite" | 3387 "aggressive" | "conservative" ] ] 3388 [ "limit" ( limit-item | "{" limit-list "}" ) ] | 3389 [ "loginterface" ( interface-name | "none" ) ] | 3390 [ "block-policy" ( "drop" | "return" ) ] | 3391 [ "state-policy" ( "if-bound" | "floating" ) ] 3392 [ "state-defaults" state-opts ] 3393 [ "require-order" ( "yes" | "no" ) ] 3394 [ "fingerprints" filename ] | 3395 [ "skip on" ifspec ] | 3396 [ "debug" ( "none" | "urgent" | "misc" | "loud" ) ] 3397 [ "keepcounters" ] ) 3398 3399ether-rule = "ether" etheraction [ ( "in" | "out" ) ] 3400 [ "quick" ] [ "on" ifspec ] [ "bridge-to" interface-name ] 3401 [ etherprotospec ] [ etherhosts ] [ "l3" hosts ] 3402 [ etherfilteropt-list ] 3403 3404pf-rule = action [ ( "in" | "out" ) ] 3405 [ "log" [ "(" logopts ")"] ] [ "quick" ] 3406 [ "on" ifspec ] [ route ] [ af ] [ protospec ] 3407 [ hosts ] [ filteropt-list ] 3408 3409logopts = logopt [ "," logopts ] 3410logopt = "all" | "matches" | "user" | "to" interface-name 3411 3412etherfilteropt-list = etherfilteropt-list etherfilteropt | etherfilteropt 3413etherfilteropt = "tag" string | "tagged" string | "queue" ( string ) | 3414 "ridentifier" number | "label" string 3415 3416filteropt-list = filteropt-list filteropt | filteropt 3417filteropt = user | group | flags | icmp-type | icmp6-type | "tos" tos | 3418 "af-to" af "from" ( redirhost | "{" redirhost-list "}" ) 3419 [ "to" ( redirhost | "{" redirhost-list "}" ) ] | 3420 ( "no" | "keep" | "modulate" | "synproxy" ) "state" 3421 [ "(" state-opts ")" ] | 3422 "fragment" | "no-df" | "min-ttl" number | "set-tos" tos | 3423 "max-mss" number | "random-id" | "reassemble tcp" | 3424 fragmentation | "allow-opts" | 3425 "label" string | "tag" string | [ "!" ] "tagged" string | 3426 "max-pkt-rate" number "/" seconds | 3427 "set prio" ( number | "(" number [ [ "," ] number ] ")" ) | 3428 "max-pkt-size" number | 3429 "queue" ( string | "(" string [ [ "," ] string ] ")" ) | 3430 "rtable" number | "probability" number"%" | "prio" number | 3431 "dnpipe" ( number | "(" number "," number ")" ) | 3432 "dnqueue" ( number | "(" number "," number ")" ) | 3433 "ridentifier" number | 3434 [ ! ] "received-on" ( interface-name | interface-group ) 3435 3436nat-rule = [ "no" ] "nat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 3437 [ "on" ifspec ] [ af ] 3438 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 3439 [ "->" ( redirhost | "{" redirhost-list "}" ) 3440 [ portspec ] [ pooltype ] [ "static-port" ] 3441 [ "map-e-portset" number "/" number "/" number ] ] 3442 3443binat-rule = [ "no" ] "binat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 3444 [ "on" interface-name ] [ af ] 3445 [ "proto" ( proto-name | proto-number ) ] 3446 "from" address [ "/" mask-bits ] "to" ipspec 3447 [ "tag" string ] [ "tagged" string ] 3448 [ "->" address [ "/" mask-bits ] ] 3449 3450rdr-rule = [ "no" ] "rdr" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 3451 [ "on" ifspec ] [ af ] 3452 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 3453 [ "->" ( redirhost | "{" redirhost-list "}" ) 3454 [ portspec ] [ pooltype ] ] 3455 3456antispoof-rule = "antispoof" [ "log" ] [ "quick" ] 3457 "for" ifspec [ af ] [ "label" string ] 3458 [ "ridentifier" number ] 3459 3460table-rule = "table" "<" string ">" [ tableopts-list ] 3461tableopts-list = tableopts-list tableopts | tableopts 3462tableopts = "persist" | "const" | "counters" | "file" string | 3463 "{" [ tableaddr-list ] "}" 3464tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec 3465tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ] 3466tableaddr = hostname | ifspec | "self" | 3467 ipv4-dotted-quad | ipv6-coloned-hex 3468 3469altq-rule = "altq on" interface-name queueopts-list 3470 "queue" subqueue 3471queue-rule = "queue" string [ "on" interface-name ] queueopts-list 3472 subqueue 3473 3474anchor-rule = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ] 3475 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ] 3476 3477anchor-close = "}" 3478 3479trans-anchors = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string 3480 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ] 3481 3482load-anchor = "load anchor" string "from" filename 3483 3484queueopts-list = queueopts-list queueopts | queueopts 3485queueopts = [ "bandwidth" bandwidth-spec ] | 3486 [ "qlimit" number ] | [ "tbrsize" number ] | 3487 [ "priority" number ] | [ schedulers ] 3488schedulers = ( cbq-def | priq-def | hfsc-def ) 3489bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" ) 3490 3491etheraction = "pass" | "block" 3492action = "pass" | "match" | "block" [ return ] | [ "no" ] "scrub" 3493return = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] | 3494 "return-icmp" [ "(" icmpcode [ [ "," ] icmp6code ] ")" ] | 3495 "return-icmp6" [ "(" icmp6code ")" ] 3496icmpcode = ( icmp-code-name | icmp-code-number ) 3497icmp6code = ( icmp6-code-name | icmp6-code-number ) 3498 3499ifspec = ( [ "!" ] ( interface-name | interface-group ) ) | 3500 "{" interface-list "}" 3501interface-list = [ "!" ] ( interface-name | interface-group ) 3502 [ [ "," ] interface-list ] 3503route = ( "route-to" | "reply-to" | "dup-to" ) 3504 ( routehost | "{" routehost-list "}" ) 3505 [ pooltype ] 3506af = "inet" | "inet6" 3507 3508etherprotospec = "proto" ( proto-number | "{" etherproto-list "}" ) 3509etherproto-list = proto-number [ [ "," ] etherproto-list ] 3510protospec = "proto" ( proto-name | proto-number | 3511 "{" proto-list "}" ) 3512proto-list = ( proto-name | proto-number ) [ [ "," ] proto-list ] 3513 3514etherhosts = "from" macaddress "to" macaddress 3515macaddress = mac | mac "/" masklen | mac "&" mask 3516 3517hosts = "all" | 3518 "from" ( "any" | "no-route" | "urpf-failed" | "self" | host | 3519 "{" host-list "}" ) [ port ] [ os ] 3520 "to" ( "any" | "no-route" | "self" | host | 3521 "{" host-list "}" ) [ port ] 3522 3523ipspec = "any" | host | "{" host-list "}" 3524host = [ "!" ] ( address [ "/" mask-bits ] | "<" string ">" ) 3525redirhost = address [ "/" mask-bits ] 3526routehost = "(" interface-name [ address [ "/" mask-bits ] ] ")" 3527address = ( interface-name | interface-group | 3528 "(" ( interface-name | interface-group ) ")" | 3529 hostname | ipv4-dotted-quad | ipv6-coloned-hex ) 3530host-list = host [ [ "," ] host-list ] 3531redirhost-list = redirhost [ [ "," ] redirhost-list ] 3532routehost-list = routehost [ [ "," ] routehost-list ] 3533 3534port = "port" ( unary-op | binary-op | "{" op-list "}" ) 3535portspec = "port" ( number | name ) [ ":" ( "*" | number | name ) ] 3536os = "os" ( os-name | "{" os-list "}" ) 3537user = "user" ( unary-op | binary-op | "{" op-list "}" ) 3538group = "group" ( unary-op | binary-op | "{" op-list "}" ) 3539 3540unary-op = [ "=" | "!=" | "<" | "<=" | ">" | ">=" ] 3541 ( name | number ) 3542binary-op = number ( "<>" | "><" | ":" ) number 3543op-list = ( unary-op | binary-op ) [ [ "," ] op-list ] 3544 3545os-name = operating-system-name 3546os-list = os-name [ [ "," ] os-list ] 3547 3548flags = "flags" ( [ flag-set ] "/" flag-set | "any" ) 3549flag-set = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ] 3550 [ "W" ] 3551 3552icmp-type = "icmp-type" ( icmp-type-code | "{" icmp-list "}" ) 3553icmp6-type = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" ) 3554icmp-type-code = ( icmp-type-name | icmp-type-number ) 3555 [ "code" ( icmp-code-name | icmp-code-number ) ] 3556icmp-list = icmp-type-code [ [ "," ] icmp-list ] 3557 3558tos = ( "lowdelay" | "throughput" | "reliability" | 3559 [ "0x" ] number ) 3560 3561state-opts = state-opt [ [ "," ] state-opts ] 3562state-opt = ( "max" number | "no-sync" | timeout | "sloppy" | 3563 "source-track" [ ( "rule" | "global" ) ] | 3564 "max-src-nodes" number | "max-src-states" number | 3565 "max-src-conn" number | 3566 "max-src-conn-rate" number "/" number | 3567 "overload" "<" string ">" [ "flush" ] | 3568 "if-bound" | "floating" | "pflow" ) 3569 3570fragmentation = [ "fragment reassemble" ] 3571 3572timeout-list = timeout [ [ "," ] timeout-list ] 3573timeout = ( "tcp.first" | "tcp.opening" | "tcp.established" | 3574 "tcp.closing" | "tcp.finwait" | "tcp.closed" | 3575 "sctp.first" | "sctp.opening" | "sctp.established" | 3576 "sctp.closing" | "sctp.closed" | 3577 "udp.first" | "udp.single" | "udp.multiple" | 3578 "icmp.first" | "icmp.error" | 3579 "other.first" | "other.single" | "other.multiple" | 3580 "frag" | "interval" | "src.track" | 3581 "adaptive.start" | "adaptive.end" ) number 3582 3583limit-list = limit-item [ [ "," ] limit-list ] 3584limit-item = ( "states" | "frags" | "src-nodes" ) number 3585 3586pooltype = ( "bitmask" | "random" | 3587 "source-hash" [ ( hex-key | string-key ) ] | 3588 "round-robin" ) [ sticky-address ] 3589 3590subqueue = string | "{" queue-list "}" 3591queue-list = string [ [ "," ] string ] 3592cbq-def = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ] 3593priq-def = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ] 3594hfsc-def = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ] 3595cbq-opt = ( "default" | "borrow" | "red" | "ecn" | "rio" ) 3596priq-opt = ( "default" | "red" | "ecn" | "rio" ) 3597hfsc-opt = ( "default" | "red" | "ecn" | "rio" | 3598 linkshare-sc | realtime-sc | upperlimit-sc ) 3599linkshare-sc = "linkshare" sc-spec 3600realtime-sc = "realtime" sc-spec 3601upperlimit-sc = "upperlimit" sc-spec 3602sc-spec = ( bandwidth-spec | 3603 "(" bandwidth-spec number bandwidth-spec ")" ) 3604include = "include" filename 3605.Ed 3606.Sh FILES 3607.Bl -tag -width "/etc/protocols" -compact 3608.It Pa /etc/hosts 3609Host name database. 3610.It Pa /etc/pf.conf 3611Default location of the ruleset file. 3612The file has to be created manually as it is not installed with a 3613standard installation. 3614.It Pa /etc/pf.os 3615Default location of OS fingerprints. 3616.It Pa /etc/protocols 3617Protocol name database. 3618.It Pa /etc/services 3619Service name database. 3620.El 3621.Sh SEE ALSO 3622.Xr altq 4 , 3623.Xr carp 4 , 3624.Xr icmp 4 , 3625.Xr icmp6 4 , 3626.Xr ip 4 , 3627.Xr ip6 4 , 3628.Xr pf 4 , 3629.Xr pflow 4 , 3630.Xr pfsync 4 , 3631.Xr sctp 4 , 3632.Xr tcp 4 , 3633.Xr udp 4 , 3634.Xr hosts 5 , 3635.Xr pf.os 5 , 3636.Xr protocols 5 , 3637.Xr services 5 , 3638.Xr ftp-proxy 8 , 3639.Xr pfctl 8 , 3640.Xr pflogd 8 3641.Sh HISTORY 3642The 3643.Nm 3644file format first appeared in 3645.Ox 3.0 . 3646