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 May 26, 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. 103.Pp 104For example, 105.Bd -literal -offset indent 106ext_if = \&"kue0\&" 107all_ifs = \&"{\&" $ext_if lo0 \&"}\&" 108pass out on $ext_if from any to any 109pass in on $ext_if proto tcp from any to any port 25 110.Ed 111.Sh TABLES 112Tables are named structures which can hold a collection of addresses and 113networks. 114Lookups against tables in 115.Xr pf 4 116are relatively fast, making a single rule with tables much more efficient, 117in terms of 118processor usage and memory consumption, than a large number of rules which 119differ only in IP address (either created explicitly or automatically by rule 120expansion). 121.Pp 122Tables can be used as the source or destination of filter rules, 123.Ar scrub 124rules 125or 126translation rules such as 127.Ar nat 128or 129.Ar rdr 130(see below for details on the various rule types). 131Tables can also be used for the redirect address of 132.Ar nat 133and 134.Ar rdr 135and in the routing options of filter rules, but not for 136.Ar bitmask 137pools. 138.Pp 139Tables can be defined with any of the following 140.Xr pfctl 8 141mechanisms. 142As with macros, reserved words may not be used as table names. 143.Bl -tag -width "manually" 144.It Ar manually 145Persistent tables can be manually created with the 146.Ar add 147or 148.Ar replace 149option of 150.Xr pfctl 8 , 151before or after the ruleset has been loaded. 152.It Pa pf.conf 153Table definitions can be placed directly in this file, and loaded at the 154same time as other rules are loaded, atomically. 155Table definitions inside 156.Nm pf.conf 157use the 158.Ar table 159statement, and are especially useful to define non-persistent tables. 160The contents of a pre-existing table defined without a list of addresses 161to initialize it is not altered when 162.Nm pf.conf 163is loaded. 164A table initialized with the empty list, 165.Li { } , 166will be cleared on load. 167.El 168.Pp 169Tables may be defined with the following attributes: 170.Bl -tag -width counters 171.It Ar persist 172The 173.Ar persist 174flag forces the kernel to keep the table even when no rules refer to it. 175If the flag is not set, the kernel will automatically remove the table 176when the last rule referring to it is flushed. 177.It Ar const 178The 179.Ar const 180flag prevents the user from altering the contents of the table once it 181has been created. 182Without that flag, 183.Xr pfctl 8 184can be used to add or remove addresses from the table at any time, even 185when running with 186.Xr securelevel 7 187= 2. 188.It Ar counters 189The 190.Ar counters 191flag enables per-address packet and byte counters which can be displayed with 192.Xr pfctl 8 . 193Note that this feature carries significant memory overhead for large tables. 194.El 195.Pp 196For example, 197.Bd -literal -offset indent 198table <private> const { 10/8, 172.16/12, 192.168/16 } 199table <badhosts> persist 200block on fxp0 from { <private>, <badhosts> } to any 201.Ed 202.Pp 203creates a table called private, to hold RFC 1918 private network 204blocks, and a table called badhosts, which is initially empty. 205A filter rule is set up to block all traffic coming from addresses listed in 206either table. 207The private table cannot have its contents changed and the badhosts table 208will exist even when no active filter rules reference it. 209Addresses may later be added to the badhosts table, so that traffic from 210these hosts can be blocked by using 211.Bd -literal -offset indent 212# pfctl -t badhosts -Tadd 204.92.77.111 213.Ed 214.Pp 215A table can also be initialized with an address list specified in one or more 216external files, using the following syntax: 217.Bd -literal -offset indent 218table <spam> persist file \&"/etc/spammers\&" file \&"/etc/openrelays\&" 219block on fxp0 from <spam> to any 220.Ed 221.Pp 222The files 223.Pa /etc/spammers 224and 225.Pa /etc/openrelays 226list IP addresses, one per line. 227Any lines beginning with a # are treated as comments and ignored. 228In addition to being specified by IP address, hosts may also be 229specified by their hostname. 230When the resolver is called to add a hostname to a table, 231.Em all 232resulting IPv4 and IPv6 addresses are placed into the table. 233IP addresses can also be entered in a table by specifying a valid interface 234name, a valid interface group or the 235.Em self 236keyword, in which case all addresses assigned to the interface(s) will be 237added to the table. 238.Sh OPTIONS 239.Xr pf 4 240may be tuned for various situations using the 241.Ar set 242command. 243.Bl -tag -width xxxx 244.It Ar set timeout 245.Pp 246.Bl -tag -width "src.track" -compact 247.It Ar interval 248Interval between purging expired states and fragments. 249.It Ar frag 250Seconds before an unassembled fragment is expired. 251.It Ar src.track 252Length of time to retain a source tracking entry after the last state 253expires. 254.El 255.Pp 256When a packet matches a stateful connection, the seconds to live for the 257connection will be updated to that of the 258.Ar proto.modifier 259which corresponds to the connection state. 260Each packet which matches this state will reset the TTL. 261Tuning these values may improve the performance of the 262firewall at the risk of dropping valid idle connections. 263.Pp 264.Bl -tag -width xxxx -compact 265.It Ar tcp.first 266The state after the first packet. 267.It Ar tcp.opening 268The state after the second packet but before both endpoints have 269acknowledged the connection. 270.It Ar tcp.established 271The fully established state. 272.It Ar tcp.closing 273The state after the first FIN has been sent. 274.It Ar tcp.finwait 275The state after both FINs have been exchanged and the connection is closed. 276Some hosts (notably web servers on Solaris) send TCP packets even after closing 277the connection. 278Increasing 279.Ar tcp.finwait 280(and possibly 281.Ar tcp.closing ) 282can prevent blocking of such packets. 283.It Ar tcp.closed 284The state after one endpoint sends an RST. 285.El 286.Pp 287SCTP timeout are handled similar to TCP, but with its own set of states: 288.Pp 289.Bl -tag -width xxxx -compact 290.It Ar sctp.first 291The state after the first packet. 292.It Ar sctp.opening 293The state before the destination host ever sends a packet. 294.It Ar sctp.established 295The fully established state. 296.It Ar sctp.closing 297The state after the first SHUTDOWN chunk has been sent. 298.It Ar sctp.closed 299The state after SHUTDOWN_ACK has been exchanged and the connection is closed. 300.El 301.Pp 302ICMP and UDP are handled in a fashion similar to TCP, but with a much more 303limited set of states: 304.Pp 305.Bl -tag -width xxxx -compact 306.It Ar udp.first 307The state after the first packet. 308.It Ar udp.single 309The state if the source host sends more than one packet but the destination 310host has never sent one back. 311.It Ar udp.multiple 312The state if both hosts have sent packets. 313.It Ar icmp.first 314The state after the first packet. 315.It Ar icmp.error 316The state after an ICMP error came back in response to an ICMP packet. 317.El 318.Pp 319Other protocols are handled similarly to UDP: 320.Pp 321.Bl -tag -width xxxx -compact 322.It Ar other.first 323.It Ar other.single 324.It Ar other.multiple 325.El 326.Pp 327Timeout values can be reduced adaptively as the number of state table 328entries grows. 329.Pp 330.Bl -tag -width xxxx -compact 331.It Ar adaptive.start 332When the number of state entries exceeds this value, adaptive scaling 333begins. 334All timeout values are scaled linearly with factor 335(adaptive.end - number of states) / (adaptive.end - adaptive.start). 336.It Ar adaptive.end 337When reaching this number of state entries, all timeout values become 338zero, effectively purging all state entries immediately. 339This value is used to define the scale factor, it should not actually 340be reached (set a lower state limit, see below). 341.El 342.Pp 343Adaptive timeouts are enabled by default, with an adaptive.start value 344equal to 60% of the state limit, and an adaptive.end value equal to 345120% of the state limit. 346They can be disabled by setting both adaptive.start and adaptive.end to 0. 347.Pp 348The adaptive timeout values can be defined both globally and for each rule. 349When used on a per-rule basis, the values relate to the number of 350states created by the rule, otherwise to the total number of 351states. 352.Pp 353For example: 354.Bd -literal -offset indent 355set timeout tcp.first 120 356set timeout tcp.established 86400 357set timeout { adaptive.start 6000, adaptive.end 12000 } 358set limit states 10000 359.Ed 360.Pp 361With 9000 state table entries, the timeout values are scaled to 50% 362(tcp.first 60, tcp.established 43200). 363.It Ar set loginterface 364Enable collection of packet and byte count statistics for the given 365interface or interface group. 366These statistics can be viewed using 367.Bd -literal -offset indent 368# pfctl -s info 369.Ed 370.Pp 371In this example 372.Xr pf 4 373collects statistics on the interface named dc0: 374.Bd -literal -offset indent 375set loginterface dc0 376.Ed 377.Pp 378One can disable the loginterface using: 379.Bd -literal -offset indent 380set loginterface none 381.Ed 382.It Ar set limit 383Sets hard limits on the memory pools used by the packet filter. 384See 385.Xr zone 9 386for an explanation of memory pools. 387.Pp 388For example, 389.Bd -literal -offset indent 390set limit states 20000 391.Ed 392.Pp 393sets the maximum number of entries in the memory pool used by state table 394entries (generated by 395.Ar pass 396rules which do not specify 397.Ar no state ) 398to 20000. 399Using 400.Bd -literal -offset indent 401set limit frags 20000 402.Ed 403.Pp 404sets the maximum number of entries in the memory pool used for fragment 405reassembly (generated by the 406.Ar set reassemble 407option or 408.Ar scrub 409rules) to 20000. 410Using 411.Bd -literal -offset indent 412set limit src-nodes 2000 413.Ed 414.Pp 415sets the maximum number of entries in the memory pool used for tracking 416source IP addresses (generated by the 417.Ar sticky-address 418and 419.Ar src.track 420options) to 2000. 421Using 422.Bd -literal -offset indent 423set limit table-entries 100000 424.Ed 425.Pp 426sets the limit on the overall number of addresses that can be stored 427in tables to 100000. 428.Pp 429Various limits can be combined on a single line: 430.Bd -literal -offset indent 431set limit { states 20000, frags 20000, src-nodes 2000 } 432.Ed 433.It Ar set ruleset-optimization 434.Bl -tag -width xxxxxxxx -compact 435.It Ar none 436Disable the ruleset optimizer. 437.It Ar basic 438Enable basic ruleset optimization. 439This is the default behaviour. 440Basic ruleset optimization does four things to improve the 441performance of ruleset evaluations: 442.Pp 443.Bl -enum -compact 444.It 445remove duplicate rules 446.It 447remove rules that are a subset of another rule 448.It 449combine multiple rules into a table when advantageous 450.It 451re-order the rules to improve evaluation performance 452.El 453.Pp 454.It Ar profile 455Uses the currently loaded ruleset as a feedback profile to tailor the 456ordering of quick rules to actual network traffic. 457.El 458.Pp 459It is important to note that the ruleset optimizer will modify the ruleset 460to improve performance. 461A side effect of the ruleset modification is that per-rule accounting 462statistics will have different meanings than before. 463If per-rule accounting is important for billing purposes or whatnot, 464either the ruleset optimizer should not be used or a label field should 465be added to all of the accounting rules to act as optimization barriers. 466.Pp 467Optimization can also be set as a command-line argument to 468.Xr pfctl 8 , 469overriding the settings in 470.Nm . 471.It Ar set optimization 472Optimize state timeouts for one of the following network environments: 473.Pp 474.Bl -tag -width xxxx -compact 475.It Ar normal 476A normal network environment. 477Suitable for almost all networks. 478.It Ar high-latency 479A high-latency environment (such as a satellite connection). 480.It Ar satellite 481Alias for 482.Ar high-latency . 483.It Ar aggressive 484Aggressively expire connections. 485This can greatly reduce the memory usage of the firewall at the cost of 486dropping idle connections early. 487.It Ar conservative 488Extremely conservative settings. 489Avoid dropping legitimate connections at the 490expense of greater memory utilization (possibly much greater on a busy 491network) and slightly increased processor utilization. 492.El 493.Pp 494For example: 495.Bd -literal -offset indent 496set optimization aggressive 497.Ed 498.It Ar set reassemble yes | no Op Cm no-df 499The 500.Cm reassemble 501option is used to enable or disable the reassembly of fragmented packets, 502and can be set to 503.Cm yes 504or 505.Cm no . 506If 507.Cm no-df 508is also specified, fragments with the 509.Dq dont-fragment 510bit set are reassembled too, 511instead of being dropped; 512the reassembled packet will have the 513.Dq dont-fragment 514bit cleared. 515The default value is 516.Cm no . 517.Pp 518This option is ignored if there are pre-FreeBSD 14 519.Cm scrub 520rules present. 521.It Ar set block-policy 522The 523.Ar block-policy 524option sets the default behaviour for the packet 525.Ar block 526action: 527.Pp 528.Bl -tag -width xxxxxxxx -compact 529.It Ar drop 530Packet is silently dropped. 531.It Ar return 532A TCP RST is returned for blocked TCP packets, 533an SCTP ABORT chunk is returned for blocked SCTP packets, 534an ICMP UNREACHABLE is returned for blocked UDP packets, 535and all other packets are silently dropped. 536.El 537.Pp 538For example: 539.Bd -literal -offset indent 540set block-policy return 541.Ed 542.It Ar set fail-policy 543The 544.Ar fail-policy 545option sets the behaviour of rules which should pass a packet but were 546unable to do so. 547This might happen when a nat or route-to rule uses an empty table as list 548of targets or if a rule fails to create state or source node. 549The following 550.Ar block 551actions are possible: 552.Pp 553.Bl -tag -width xxxxxxxx -compact 554.It Ar drop 555Incoming packet is silently dropped. 556.It Ar return 557Incoming packet is dropped and TCP RST is returned for TCP packets, 558an SCTP ABORT chunk is returned for blocked SCTP packets, 559an ICMP UNREACHABLE is returned for UDP packets, 560and no response is sent for other packets. 561.El 562.Pp 563For example: 564.Bd -literal -offset indent 565set fail-policy return 566.Ed 567.It Ar set state-policy 568The 569.Ar state-policy 570option sets the default behaviour for states: 571.Pp 572.Bl -tag -width group-bound -compact 573.It Ar if-bound 574States are bound to interface. 575.It Ar floating 576States can match packets on any interfaces (the default). 577.El 578.Pp 579For example: 580.Bd -literal -offset indent 581set state-policy if-bound 582.Ed 583.It Ar set syncookies never | always | adaptive 584When 585.Cm syncookies 586are active, pf will answer each incoming TCP SYN with a syncookie SYNACK, 587without allocating any resources. 588Upon reception of the client's ACK in response to the syncookie 589SYNACK, pf will evaluate the ruleset and create state if the ruleset 590permits it, complete the three way handshake with the target host and 591continue the connection with synproxy in place. 592This allows pf to be resilient against large synflood attacks which would 593run the state table against its limits otherwise. 594Due to the blind answers to every incoming SYN syncookies share the caveats of 595synproxy, namely seemingly accepting connections that will be dropped later on. 596.Pp 597.Bl -tag -width adaptive -compact 598.It Cm never 599pf will never send syncookie SYNACKs (the default). 600.It Cm always 601pf will always send syncookie SYNACKs. 602.It Cm adaptive 603pf will enable syncookie mode when a given percentage of the state table 604is used up by half-open TCP connections, as in, those that saw the initial 605SYN but didn't finish the three way handshake. 606The thresholds for entering and leaving syncookie mode can be specified using 607.Bd -literal -offset indent 608set syncookies adaptive (start 25%, end 12%) 609.Ed 610.El 611.It Ar set state-defaults 612The 613.Ar state-defaults 614option sets the state options for states created from rules 615without an explicit 616.Ar keep state . 617For example: 618.Bd -literal -offset indent 619set state-defaults no-sync 620.Ed 621.It Ar set hostid 622The 32-bit 623.Ar hostid 624identifies this firewall's state table entries to other firewalls 625in a 626.Xr pfsync 4 627failover cluster. 628By default the hostid is set to a pseudo-random value, however it may be 629desirable to manually configure it, for example to more easily identify the 630source of state table entries. 631.Bd -literal -offset indent 632set hostid 1 633.Ed 634.Pp 635The hostid may be specified in either decimal or hexadecimal. 636.It Ar set require-order 637By default 638.Xr pfctl 8 639enforces an ordering of the statement types in the ruleset to: 640.Em options , 641.Em normalization , 642.Em queueing , 643.Em translation , 644.Em filtering . 645Setting this option to 646.Ar no 647disables this enforcement. 648There may be non-trivial and non-obvious implications to an out of 649order ruleset. 650Consider carefully before disabling the order enforcement. 651.It Ar set fingerprints 652Load fingerprints of known operating systems from the given filename. 653By default fingerprints of known operating systems are automatically 654loaded from 655.Xr pf.os 5 656in 657.Pa /etc 658but can be overridden via this option. 659Setting this option may leave a small period of time where the fingerprints 660referenced by the currently active ruleset are inconsistent until the new 661ruleset finishes loading. 662.Pp 663For example: 664.Pp 665.Dl set fingerprints \&"/etc/pf.os.devel\&" 666.It Ar set skip on Aq Ar ifspec 667List interfaces for which packets should not be filtered. 668Packets passing in or out on such interfaces are passed as if pf was 669disabled, i.e. pf does not process them in any way. 670This can be useful on loopback and other virtual interfaces, when 671packet filtering is not desired and can have unexpected effects. 672For example: 673.Pp 674.Dl set skip on lo0 675.It Ar set debug 676Set the debug 677.Ar level 678to one of the following: 679.Pp 680.Bl -tag -width xxxxxxxxxxxx -compact 681.It Ar none 682Don't generate debug messages. 683.It Ar urgent 684Generate debug messages only for serious errors. 685.It Ar misc 686Generate debug messages for various errors. 687.It Ar loud 688Generate debug messages for common conditions. 689.El 690.It Ar set keepcounters 691Preserve rule counters across rule updates. 692Usually rule counters are reset to zero on every update of the ruleset. 693With 694.Ar keepcounters 695set pf will attempt to find matching rules between old and new rulesets 696and preserve the rule counters. 697.El 698.Sh ETHERNET FILTERING 699.Xr pf 4 700has the ability to 701.Ar block 702and 703.Ar pass 704packets based on attributes of their Ethernet (layer 2) header. 705.Pp 706For each packet processed by the packet filter, the filter rules are 707evaluated in sequential order, from first to last. 708The last matching rule decides what action is taken. 709If no rule matches the packet, the default action is to pass 710the packet without creating a state. 711.Pp 712The following actions can be used in the filter: 713.Bl -tag -width xxxx 714.It Ar block 715The packet is blocked. 716Unlike for layer 3 traffic the packet is always silently dropped. 717.It Ar pass 718The packet is passed; 719no state is created for layer 2 traffic. 720.El 721.Sh PARAMETERS 722The rule parameters specify the packets to which a rule applies. 723A packet always comes in on, or goes out through, one interface. 724Most parameters are optional. 725If a parameter is specified, the rule only applies to packets with 726matching attributes. 727The matching for some parameters can be inverted with the 728.Cm !\& 729operator. 730Certain parameters can be expressed as lists, in which case 731.Xr pfctl 8 732generates all needed rule combinations. 733.Bl -tag -width xxxx 734.It Ar in No or Ar out 735This rule applies to incoming or outgoing packets. 736If neither 737.Ar in 738nor 739.Ar out 740are specified, the rule will match packets in both directions. 741.It Ar quick 742If a packet matches a rule which has the 743.Ar quick 744option set, this rule 745is considered the last matching rule, and evaluation of subsequent rules 746is skipped. 747.It Ar on Aq Ar ifspec 748This rule applies only to packets coming in on, or going out through, this 749particular interface or interface group. 750For more information on interface groups, 751see the 752.Ic group 753keyword in 754.Xr ifconfig 8 . 755.Ar any 756will match any existing interface except loopback ones. 757.It Ar bridge-to Aq interface 758Packets matching this rule will be sent out of the specified interface without 759further processing. 760.It Ar proto Aq Ar protocol 761This rule applies only to packets of this protocol. 762Note that Ethernet protocol numbers are different from those used in 763.Xr ip 4 764and 765.Xr ip6 4 . 766.It Xo 767.Ar from Aq Ar source 768.Ar to Aq Ar dest 769.Xc 770This rule applies only to packets with the specified source and destination 771MAC addresses. 772.It Xo Ar queue Aq Ar queue 773.Xc 774Packets matching this rule will be assigned to the specified queue. 775See 776.Sx QUEUEING 777for setup details. 778.Pp 779.It Ar tag Aq Ar string 780Packets matching this rule will be tagged with the 781specified string. 782The tag acts as an internal marker that can be used to 783identify these packets later on. 784This can be used, for example, to provide trust between 785interfaces and to determine if packets have been 786processed by translation rules. 787Tags are 788.Qq sticky , 789meaning that the packet will be tagged even if the rule 790is not the last matching rule. 791Further matching rules can replace the tag with a 792new one but will not remove a previously applied tag. 793A packet is only ever assigned one tag at a time. 794.It Ar tagged Aq Ar string 795Used to specify that packets must already be tagged with the given tag in order 796to match the rule. 797Inverse tag matching can also be done by specifying the ! operator before the 798tagged keyword. 799.El 800.Sh TRAFFIC NORMALIZATION 801Traffic normalization is a broad umbrella term 802for aspects of the packet filter which deal with 803verifying packets, packet fragments, spoofed traffic, 804and other irregularities. 805.Ss Scrub 806Scrub involves sanitising packet content in such a way 807that there are no ambiguities in packet interpretation on the receiving side. 808It is invoked with the 809.Cm scrub 810option, added to filter rules. 811.Pp 812Parameters are specified enclosed in parentheses. 813At least one of the following parameters must be specified: 814.Bl -tag -width xxxx 815.It Ar no-df 816Clears the 817.Ar dont-fragment 818bit from a matching IP packet. 819Some operating systems are known to generate fragmented packets with the 820.Ar dont-fragment 821bit set. 822This is particularly true with NFS. 823.Ar Scrub 824will drop such fragmented 825.Ar dont-fragment 826packets unless 827.Ar no-df 828is specified. 829.Pp 830Unfortunately some operating systems also generate their 831.Ar dont-fragment 832packets with a zero IP identification field. 833Clearing the 834.Ar dont-fragment 835bit on packets with a zero IP ID may cause deleterious results if an 836upstream router later fragments the packet. 837Using the 838.Ar random-id 839modifier (see below) is recommended in combination with the 840.Ar no-df 841modifier to ensure unique IP identifiers. 842.It Ar min-ttl Aq Ar number 843Enforces a minimum TTL for matching IP packets. 844.It Ar max-mss Aq Ar number 845Enforces a maximum MSS for matching TCP packets. 846.It Xo Ar set-tos Aq Ar string 847.No \*(Ba Aq Ar number 848.Xc 849Enforces a 850.Em TOS 851for matching IP packets. 852.Em TOS 853may be 854given as one of 855.Ar critical , 856.Ar inetcontrol , 857.Ar lowdelay , 858.Ar netcontrol , 859.Ar throughput , 860.Ar reliability , 861or one of the DiffServ Code Points: 862.Ar ef , 863.Ar va , 864.Ar af11 No ... Ar af43 , 865.Ar cs0 No ... Ar cs7 ; 866or as either hex or decimal. 867.It Ar random-id 868Replaces the IP identification field with random values to compensate 869for predictable values generated by many hosts. 870This option only applies to packets that are not fragmented 871after the optional fragment reassembly. 872.It Ar reassemble tcp 873Statefully normalizes TCP connections. 874.Ar reassemble tcp 875performs the following normalizations: 876.Pp 877.Bl -tag -width timeout -compact 878.It ttl 879Neither side of the connection is allowed to reduce their IP TTL. 880An attacker may send a packet such that it reaches the firewall, affects 881the firewall state, and expires before reaching the destination host. 882.Ar reassemble tcp 883will raise the TTL of all packets back up to the highest value seen on 884the connection. 885.It timestamp modulation 886Modern TCP stacks will send a timestamp on every TCP packet and echo 887the other endpoint's timestamp back to them. 888Many operating systems will merely start the timestamp at zero when 889first booted, and increment it several times a second. 890The uptime of the host can be deduced by reading the timestamp and multiplying 891by a constant. 892Also observing several different timestamps can be used to count hosts 893behind a NAT device. 894And spoofing TCP packets into a connection requires knowing or guessing 895valid timestamps. 896Timestamps merely need to be monotonically increasing and not derived off a 897guessable base time. 898.Ar reassemble tcp 899will cause 900.Ar scrub 901to modulate the TCP timestamps with a random number. 902.It extended PAWS checks 903There is a problem with TCP on long fat pipes, in that a packet might get 904delayed for longer than it takes the connection to wrap its 32-bit sequence 905space. 906In such an occurrence, the old packet would be indistinguishable from a 907new packet and would be accepted as such. 908The solution to this is called PAWS: Protection Against Wrapped Sequence 909numbers. 910It protects against it by making sure the timestamp on each packet does 911not go backwards. 912.Ar reassemble tcp 913also makes sure the timestamp on the packet does not go forward more 914than the RFC allows. 915By doing this, 916.Xr pf 4 917artificially extends the security of TCP sequence numbers by 10 to 18 918bits when the host uses appropriately randomized timestamps, since a 919blind attacker would have to guess the timestamp as well. 920.El 921.El 922.Pp 923For example, 924.Bd -literal -offset indent 925match in all scrub (no-df random-id max-mss 1440) 926.Ed 927.Ss Scrub ruleset (pre-FreeBSD 14) 928In order to maintain compatibility with older releases of FreeBSD 929.Ar scrub 930rules can also be specified in their own ruleset. 931In such case they are invoked with the 932.Ar scrub 933directive. 934If there are such rules present they determine packet reassembly behaviour. 935When no such rules are present the option 936.Ar set reassembly 937takes precedence. 938The 939.Ar scrub 940rules can take all parameters specified above for a 941.Ar scrub 942option of filter rules and 2 more parameters controlling fragment reassembly: 943.Bl -tag -width xxxx 944.It Ar fragment reassemble 945Using 946.Ar scrub 947rules, fragments can be reassembled by normalization. 948In this case, fragments are buffered until they form a complete 949packet, and only the completed packet is passed on to the filter. 950The advantage is that filter rules have to deal only with complete 951packets, and can ignore fragments. 952The drawback of caching fragments is the additional memory cost. 953This is the default behaviour unless no fragment reassemble is specified. 954.It Ar no fragment reassemble 955Do not reassemble fragments. 956.El 957.Pp 958For example, 959.Bd -literal -offset indent 960scrub in on $ext_if all fragment reassemble 961.Ed 962.Pp 963The 964.Ar no 965option prefixed to a scrub rule causes matching packets to remain unscrubbed, 966much in the same way as 967.Ar drop quick 968works in the packet filter (see below). 969This mechanism should be used when it is necessary to exclude specific packets 970from broader scrub rules. 971.Pp 972.Ar scrub 973rules in the 974.Ar scrub 975ruleset are evaluated for every packet before stateful filtering. 976This means excessive usage of them will cause performance penalty. 977.Ar scrub reassemble tcp 978rules must not have the direction (in/out) specified. 979.Sh QUEUEING with ALTQ 980The ALTQ system is currently not available in the GENERIC kernel nor as 981loadable modules. 982In order to use the herein after called queueing options one has to use a 983custom built kernel. 984Please refer to 985.Xr altq 4 986to learn about the related kernel options. 987.Pp 988Packets can be assigned to queues for the purpose of bandwidth 989control. 990At least two declarations are required to configure queues, and later 991any packet filtering rule can reference the defined queues by name. 992During the filtering component of 993.Nm pf.conf , 994the last referenced 995.Ar queue 996name is where any packets from 997.Ar pass 998rules will be queued, while for 999.Ar block 1000rules it specifies where any resulting ICMP or TCP RST 1001packets should be queued. 1002The 1003.Ar scheduler 1004defines the algorithm used to decide which packets get delayed, dropped, or 1005sent out immediately. 1006There are three 1007.Ar schedulers 1008currently supported. 1009.Bl -tag -width xxxx 1010.It Ar cbq 1011Class Based Queueing. 1012.Ar Queues 1013attached to an interface build a tree, thus each 1014.Ar queue 1015can have further child 1016.Ar queues . 1017Each queue can have a 1018.Ar priority 1019and a 1020.Ar bandwidth 1021assigned. 1022.Ar Priority 1023mainly controls the time packets take to get sent out, while 1024.Ar bandwidth 1025has primarily effects on throughput. 1026.Ar cbq 1027achieves both partitioning and sharing of link bandwidth 1028by hierarchically structured classes. 1029Each class has its own 1030.Ar queue 1031and is assigned its share of 1032.Ar bandwidth . 1033A child class can borrow bandwidth from its parent class 1034as long as excess bandwidth is available 1035(see the option 1036.Ar borrow , 1037below). 1038.It Ar priq 1039Priority Queueing. 1040.Ar Queues 1041are flat attached to the interface, thus, 1042.Ar queues 1043cannot have further child 1044.Ar queues . 1045Each 1046.Ar queue 1047has a unique 1048.Ar priority 1049assigned, ranging from 0 to 15. 1050Packets in the 1051.Ar queue 1052with the highest 1053.Ar priority 1054are processed first. 1055.It Ar hfsc 1056Hierarchical Fair Service Curve. 1057.Ar Queues 1058attached to an interface build a tree, thus each 1059.Ar queue 1060can have further child 1061.Ar queues . 1062Each queue can have a 1063.Ar priority 1064and a 1065.Ar bandwidth 1066assigned. 1067.Ar Priority 1068mainly controls the time packets take to get sent out, while 1069.Ar bandwidth 1070primarily affects throughput. 1071.Ar hfsc 1072supports both link-sharing and guaranteed real-time services. 1073It employs a service curve based QoS model, 1074and its unique feature is an ability to decouple 1075.Ar delay 1076and 1077.Ar bandwidth 1078allocation. 1079.El 1080.Pp 1081The interfaces on which queueing should be activated are declared using 1082the 1083.Ar altq on 1084declaration. 1085.Ar altq on 1086has the following keywords: 1087.Bl -tag -width xxxx 1088.It Aq Ar interface 1089Queueing is enabled on the named interface. 1090.It Aq Ar scheduler 1091Specifies which queueing scheduler to use. 1092Currently supported values 1093are 1094.Ar cbq 1095for Class Based Queueing, 1096.Ar priq 1097for Priority Queueing and 1098.Ar hfsc 1099for the Hierarchical Fair Service Curve scheduler. 1100.It Ar bandwidth Aq Ar bw 1101The maximum bitrate for all queues on an 1102interface may be specified using the 1103.Ar bandwidth 1104keyword. 1105The value can be specified as an absolute value or as a 1106percentage of the interface bandwidth. 1107When using an absolute value, the suffixes 1108.Ar b , 1109.Ar Kb , 1110.Ar Mb , 1111and 1112.Ar Gb 1113are used to represent bits, kilobits, megabits, and 1114gigabits per second, respectively. 1115The value must not exceed the interface bandwidth. 1116If 1117.Ar bandwidth 1118is not specified, the interface bandwidth is used 1119(but take note that some interfaces do not know their bandwidth, 1120or can adapt their bandwidth rates). 1121.It Ar qlimit Aq Ar limit 1122The maximum number of packets held in the queue. 1123The default is 50. 1124.It Ar tbrsize Aq Ar size 1125Adjusts the size, in bytes, of the token bucket regulator. 1126If not specified, heuristics based on the 1127interface bandwidth are used to determine the size. 1128.It Ar queue Aq Ar list 1129Defines a list of subqueues to create on an interface. 1130.El 1131.Pp 1132In the following example, the interface dc0 1133should queue up to 5Mbps in four second-level queues using 1134Class Based Queueing. 1135Those four queues will be shown in a later example. 1136.Bd -literal -offset indent 1137altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh } 1138.Ed 1139.Pp 1140Once interfaces are activated for queueing using the 1141.Ar altq 1142directive, a sequence of 1143.Ar queue 1144directives may be defined. 1145The name associated with a 1146.Ar queue 1147must match a queue defined in the 1148.Ar altq 1149directive (e.g. mail), or, except for the 1150.Ar priq 1151.Ar scheduler , 1152in a parent 1153.Ar queue 1154declaration. 1155The following keywords can be used: 1156.Bl -tag -width xxxx 1157.It Ar on Aq Ar interface 1158Specifies the interface the queue operates on. 1159If not given, it operates on all matching interfaces. 1160.It Ar bandwidth Aq Ar bw 1161Specifies the maximum bitrate to be processed by the queue. 1162This value must not exceed the value of the parent 1163.Ar queue 1164and can be specified as an absolute value or a percentage of the parent 1165queue's bandwidth. 1166If not specified, defaults to 100% of the parent queue's bandwidth. 1167The 1168.Ar priq 1169scheduler does not support bandwidth specification. 1170.It Ar priority Aq Ar level 1171Between queues a priority level can be set. 1172For 1173.Ar cbq 1174and 1175.Ar hfsc , 1176the range is 0 to 7 and for 1177.Ar priq , 1178the range is 0 to 15. 1179The default for all is 1. 1180.Ar Priq 1181queues with a higher priority are always served first. 1182.Ar Cbq 1183and 1184.Ar Hfsc 1185queues with a higher priority are preferred in the case of overload. 1186.It Ar qlimit Aq Ar limit 1187The maximum number of packets held in the queue. 1188The default is 50. 1189.El 1190.Pp 1191The 1192.Ar scheduler 1193can get additional parameters with 1194.Xo Aq Ar scheduler 1195.Pf ( Aq Ar parameters ) . 1196.Xc 1197Parameters are as follows: 1198.Bl -tag -width Fl 1199.It Ar default 1200Packets not matched by another queue are assigned to this one. 1201Exactly one default queue is required. 1202.It Ar red 1203Enable RED (Random Early Detection) on this queue. 1204RED drops packets with a probability proportional to the average 1205queue length. 1206.It Ar rio 1207Enables RIO on this queue. 1208RIO is RED with IN/OUT, thus running 1209RED two times more than RIO would achieve the same effect. 1210RIO is currently not supported in the GENERIC kernel. 1211.It Ar ecn 1212Enables ECN (Explicit Congestion Notification) on this queue. 1213ECN implies RED. 1214.El 1215.Pp 1216The 1217.Ar cbq 1218.Ar scheduler 1219supports an additional option: 1220.Bl -tag -width Fl 1221.It Ar borrow 1222The queue can borrow bandwidth from the parent. 1223.El 1224.Pp 1225The 1226.Ar hfsc 1227.Ar scheduler 1228supports some additional options: 1229.Bl -tag -width Fl 1230.It Ar realtime Aq Ar sc 1231The minimum required bandwidth for the queue. 1232.It Ar upperlimit Aq Ar sc 1233The maximum allowed bandwidth for the queue. 1234.It Ar linkshare Aq Ar sc 1235The bandwidth share of a backlogged queue. 1236.El 1237.Pp 1238.Aq Ar sc 1239is an acronym for 1240.Ar service curve . 1241.Pp 1242The format for service curve specifications is 1243.Ar ( m1 , d , m2 ) . 1244.Ar m2 1245controls the bandwidth assigned to the queue. 1246.Ar m1 1247and 1248.Ar d 1249are optional and can be used to control the initial bandwidth assignment. 1250For the first 1251.Ar d 1252milliseconds the queue gets the bandwidth given as 1253.Ar m1 , 1254afterwards the value given in 1255.Ar m2 . 1256.Pp 1257Furthermore, with 1258.Ar cbq 1259and 1260.Ar hfsc , 1261child queues can be specified as in an 1262.Ar altq 1263declaration, thus building a tree of queues using a part of 1264their parent's bandwidth. 1265.Pp 1266Packets can be assigned to queues based on filter rules by using the 1267.Ar queue 1268keyword. 1269Normally only one 1270.Ar queue 1271is specified; when a second one is specified it will instead be used for 1272packets which have a 1273.Em TOS 1274of 1275.Em lowdelay 1276and for TCP ACKs with no data payload. 1277.Pp 1278To continue the previous example, the examples below would specify the 1279four referenced 1280queues, plus a few child queues. 1281Interactive 1282.Xr ssh 1 1283sessions get priority over bulk transfers like 1284.Xr scp 1 1285and 1286.Xr sftp 1 . 1287The queues may then be referenced by filtering rules (see 1288.Sx PACKET FILTERING 1289below). 1290.Bd -literal 1291queue std bandwidth 10% cbq(default) 1292queue http bandwidth 60% priority 2 cbq(borrow red) \e 1293 { employees, developers } 1294queue developers bandwidth 75% cbq(borrow) 1295queue employees bandwidth 15% 1296queue mail bandwidth 10% priority 0 cbq(borrow ecn) 1297queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk } 1298queue ssh_interactive bandwidth 50% priority 7 cbq(borrow) 1299queue ssh_bulk bandwidth 50% priority 0 cbq(borrow) 1300 1301block return out on dc0 inet all queue std 1302pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e 1303 queue developers 1304pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e 1305 queue employees 1306pass out on dc0 inet proto tcp from any to any port 22 \e 1307 queue(ssh_bulk, ssh_interactive) 1308pass out on dc0 inet proto tcp from any to any port 25 \e 1309 queue mail 1310.Ed 1311.Sh QUEUEING with dummynet 1312Queueing can also be done with 1313.Xr dummynet 4 . 1314Queues and pipes can be created with 1315.Xr dnctl 8 . 1316.Pp 1317Packets can be assigned to queues and pipes using 1318.Ar dnqueue 1319and 1320.Ar dnpipe 1321respectively. 1322.Pp 1323Both 1324.Ar dnqueue 1325and 1326.Ar dnpipe 1327take either a single pipe or queue number or two numbers as arguments. 1328The first pipe or queue number will be used to shape the traffic in the rule 1329direction, the second will be used to shape the traffic in the reverse 1330direction. 1331If the rule does not specify a direction the first packet to create state will 1332be shaped according to the first number, and the response traffic according to 1333the second. 1334.Pp 1335If the 1336.Xr dummynet 4 1337module is not loaded any traffic sent into a queue or pipe will be dropped. 1338.Sh TRANSLATION 1339Translation options modify either the source or destination address and 1340port of the packets associated with a stateful connection. 1341.Xr pf 4 1342modifies the specified address and/or port in the packet and recalculates 1343IP, TCP, and UDP checksums as necessary. 1344.Pp 1345If specified on a 1346.Ic match 1347rule, subsequent rules will see packets as they look 1348after any addresses and ports have been translated. 1349These rules will therefore have to filter based on the translated 1350address and port number. 1351.Pp 1352The state entry created permits 1353.Xr pf 4 1354to keep track of the original address for traffic associated with that state 1355and correctly direct return traffic for that connection. 1356.Pp 1357Various types of translation are possible with pf: 1358.Bl -tag -width xxxx 1359.It Ar af-to 1360Translation between different address families (NAT64) is handled 1361using 1362.Ar af-to 1363rules. 1364Because address family translation overrides the routing table, it's 1365only possible to use 1366.Ar af-to 1367on inbound rules, and a source address of the resulting translation 1368must always be specified. 1369.Pp 1370The optional second argument is the host or subnet the original 1371addresses are translated into for the destination. 1372The lowest bits of the original destination address form the host 1373part of the new destination address according to the specified subnet. 1374It is possible to embed a complete IPv4 address into an IPv6 address 1375using a network prefix of /96 or smaller. 1376.Pp 1377When a destination address is not specified it is assumed that the host 1378part is 32-bit long. 1379For IPv6 to IPv4 translation this would mean using only the lower 32 1380bits of the original IPv6 destination address. 1381For IPv4 to IPv6 translation the destination subnet defaults to the 1382subnet of the new IPv6 source address with a prefix length of /96. 1383See RFC 6052 Section 2.2 for details on how the prefix determines the 1384destination address encoding. 1385.Pp 1386For example, the following rules are identical: 1387.Bd -literal -offset indent 1388pass in inet af-to inet6 from 2001:db8::1 to 2001:db8::/96 1389pass in inet af-to inet6 from 2001:db8::1 1390.Ed 1391.Pp 1392In the above example the matching IPv4 packets will be modified to 1393have a source address of 2001:db8::1 and a destination address will 1394get prefixed with 2001:db8::/96, e.g. 198.51.100.100 will be 1395translated to 2001:db8::c633:6464. 1396.Pp 1397In the reverse case the following rules are identical: 1398.Bd -literal -offset indent 1399pass in inet6 from any to 64:ff9b::/96 af-to inet \e 1400 from 198.51.100.1 to 0.0.0.0/0 1401pass in inet6 from any to 64:ff9b::/96 af-to inet \e 1402 from 198.51.100.1 1403.Ed 1404.Pp 1405The destination IPv4 address is assumed to be embedded inside the 1406original IPv6 destination address, e.g. 64:ff9b::c633:6464 will be 1407translated to 198.51.100.100. 1408.Pp 1409The current implementation will only extract IPv4 addresses from the 1410IPv6 addresses with a prefix length of /96 and greater. 1411.It Ar binat 1412A 1413.Ar binat-to 1414rule specifies a bidirectional mapping between an external IP netblock 1415and an internal IP netblock. 1416It expands to an outbound 1417.Ar nat-to 1418rule and an inbound 1419.Ar rdr-to 1420rule. 1421.It Ar nat-to 1422A 1423.Ar nat-to 1424option specifies that IP addresses are to be changed as the packet 1425traverses the given interface. 1426This technique allows one or more IP addresses 1427on the translating host to support network traffic for a larger range of 1428machines on an "inside" network. 1429Although in theory any IP address can be used on the inside, it is strongly 1430recommended that one of the address ranges defined by RFC 1918 be used. 1431These netblocks are: 1432.Bd -literal -offset indent 143310.0.0.0 - 10.255.255.255 (all of net 10.0.0.0, i.e., 10.0.0.0/8) 1434172.16.0.0 - 172.31.255.255 (i.e., 172.16.0.0/12) 1435192.168.0.0 - 192.168.255.255 (i.e., 192.168.0.0/16) 1436.Ed 1437.Pp 1438.Ar nat-to 1439is usually applied outbound. 1440If applied inbound, nat-to to a local IP address is not supported. 1441.It Pa rdr-to 1442The packet is redirected to another destination and possibly a 1443different port. 1444.Ar rdr-to 1445can optionally specify port ranges instead of single ports. 1446For instance: 1447.Bd -literal -offset indent 1448match in ... port 2000:2999 rdr-to ... port 4000 1449.Ed 1450redirects ports 2000 to 2999 (inclusive) to port 4000. 1451.Bd -literal -offset indent 1452qmatch in ... port 2000:2999 rdr-to ... port 4000:* 1453.Ed 1454redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999. 1455.El 1456.Pp 1457.Ar rdr-to 1458is usually applied inbound. 1459If applied outbound, rdr-to to a local IP address is not supported. 1460In addition to modifying the address, some translation rules may modify 1461source or destination ports for 1462.Xr tcp 4 1463or 1464.Xr udp 4 1465connections; implicitly in the case of 1466.Ar nat-to 1467options and both implicitly and explicitly in the case of 1468.Ar rdr-to 1469ones. 1470A 1471.Ar rdr-to 1472opion may cause the source port to be modified if doing so avoids a conflict 1473with an existing connection. 1474A random source port in the range 50001-65535 is chosen in this case; to 1475avoid excessive CPU consumption, the number of searches for a free port is 1476limited by the 1477.Va net.pf.rdqr_srcport_rewrite_tries 1478sysctl. 1479Port numbers are never translated with a 1480.Ar binat-to 1481option. 1482.Pp 1483Note that redirecting external incoming connections to the loopback 1484address, as in 1485.Bd -literal -offset indent 1486pass in on egress proto tcp from any to any port smtp \e 1487 rdr-to 127.0.0.1 port spamd 1488.Ed 1489.Pp 1490will effectively allow an external host to connect to daemons 1491bound solely to the loopback address, circumventing the traditional 1492blocking of such connections on a real interface. 1493Unless this effect is desired, any of the local non-loopback addresses 1494should be used as redirection target instead, which allows external 1495connections only to daemons bound to this address or not bound to 1496any address. 1497.Pp 1498See 1499.Sx TRANSLATION EXAMPLES 1500below. 1501.Ss NAT ruleset (pre-FreeBSD 15) 1502In order to maintain compatibility with older releases of FreeBSD 1503.Ar NAT 1504rules can also be specified in their own ruleset. 1505A stateful connection is automatically created to track packets matching 1506such a rule as long as they are not blocked by the filtering section of 1507.Nm pf.conf . 1508Since translation occurs before filtering the filter 1509engine will see packets as they look after any 1510addresses and ports have been translated. 1511Filter rules will therefore have to filter based on the translated 1512address and port number. 1513Packets that match a translation rule are only automatically passed if 1514the 1515.Ar pass 1516modifier is given, otherwise they are 1517still subject to 1518.Ar block 1519and 1520.Ar pass 1521rules. 1522.Pp 1523The following rules can be defined in the NAT ruleset: 1524.Ar binat , 1525.Ar nat , 1526and 1527.Ar rdr . 1528They have the same effect as 1529.Ar binat-to , 1530.Ar nat-to 1531and 1532.Ar rdr-to 1533options for filter rules. 1534.Pp 1535The 1536.Ar no 1537option prefixed to a translation rule causes packets to remain untranslated, 1538much in the same way as 1539.Ar drop quick 1540works in the packet filter. 1541If no rule matches the packet it is passed to the filter engine unmodified. 1542.Pp 1543Evaluation order of the translation rules is dependent on the type 1544of the translation rules and of the direction of a packet. 1545.Ar binat 1546rules are always evaluated first. 1547Then either the 1548.Ar rdr 1549rules are evaluated on an inbound packet or the 1550.Ar nat 1551rules on an outbound packet. 1552Rules of the same type are evaluated in the same order in which they 1553appear in the ruleset. 1554The first matching rule decides what action is taken. 1555.Pp 1556Translation rules apply only to packets that pass through 1557the specified interface, and if no interface is specified, 1558translation is applied to packets on all interfaces. 1559For instance, redirecting port 80 on an external interface to an internal 1560web server will only work for connections originating from the outside. 1561Connections to the address of the external interface from local hosts will 1562not be redirected, since such packets do not actually pass through the 1563external interface. 1564Redirections cannot reflect packets back through the interface they arrive 1565on, they can only be redirected to hosts connected to different interfaces 1566or to the firewall itself. 1567.Pp 1568See 1569.Sx COMPATIBILITY TRANSLATION EXAMPLES 1570below. 1571.Sh PACKET FILTERING 1572.Xr pf 4 1573has the ability to 1574.Ar block 1575, 1576.Ar pass 1577and 1578.Ar match 1579packets based on attributes of their layer 3 (see 1580.Xr ip 4 1581and 1582.Xr ip6 4 ) 1583and layer 4 (see 1584.Xr icmp 4 , 1585.Xr icmp6 4 , 1586.Xr tcp 4 , 1587.Xr sctp 4 , 1588.Xr udp 4 ) 1589headers. 1590In addition, packets may also be 1591assigned to queues for the purpose of bandwidth control. 1592.Pp 1593For each packet processed by the packet filter, the filter rules are 1594evaluated in sequential order, from first to last. 1595For 1596.Ar block 1597and 1598.Ar pass 1599, the last matching rule decides what action is taken. 1600For 1601.Ar match 1602, rules are evaluated every time they match; the pass/block state of a packet 1603remains unchanged. 1604If no rule matches the packet, the default action is to pass 1605the packet. 1606.Pp 1607The following actions can be used in the filter: 1608.Bl -tag -width xxxx 1609.It Ar block 1610The packet is blocked. 1611There are a number of ways in which a 1612.Ar block 1613rule can behave when blocking a packet. 1614The default behaviour is to 1615.Ar drop 1616packets silently, however this can be overridden or made 1617explicit either globally, by setting the 1618.Ar block-policy 1619option, or on a per-rule basis with one of the following options: 1620.Pp 1621.Bl -tag -width xxxx -compact 1622.It Ar drop 1623The packet is silently dropped. 1624.It Ar return-rst 1625This applies only to 1626.Xr tcp 4 1627packets, and issues a TCP RST which closes the 1628connection. 1629.It Ar return-icmp 1630.It Ar return-icmp6 1631This causes ICMP messages to be returned for packets which match the rule. 1632By default this is an ICMP UNREACHABLE message, however this 1633can be overridden by specifying a message as a code or number. 1634.It Ar return 1635This causes a TCP RST to be returned for 1636.Xr tcp 4 1637packets, an SCTP ABORT for SCTP 1638and an ICMP UNREACHABLE for UDP and other packets. 1639.El 1640.Pp 1641Options returning ICMP packets currently have no effect if 1642.Xr pf 4 1643operates on a 1644.Xr if_bridge 4 , 1645as the code to support this feature has not yet been implemented. 1646.Pp 1647The simplest mechanism to block everything by default and only pass 1648packets that match explicit rules is specify a first filter rule of: 1649.Bd -literal -offset indent 1650block all 1651.Ed 1652.It Ar match 1653The packet is matched. 1654This mechanism is used to provide fine grained filtering without altering the 1655block/pass state of a packet. 1656.Ar match 1657rules differ from 1658.Ar block 1659and 1660.Ar pass 1661rules in that parameters are set for every rule a packet matches, not only 1662on the last matching rule. 1663For the following parameters, this means that the parameter effectively becomes 1664"sticky" until explicitly overridden: 1665.Ar nat-to , 1666.Ar binat-to , 1667.Ar rdr-to , 1668.Ar queue , 1669.Ar dnpipe , 1670.Ar dnqueue , 1671.Ar rtable , 1672.Ar scrub 1673. 1674.It Ar pass 1675The packet is passed; 1676state is created unless the 1677.Ar no state 1678option is specified. 1679.El 1680.Pp 1681By default 1682.Xr pf 4 1683filters packets statefully; the first time a packet matches a 1684.Ar pass 1685rule, a state entry is created; for subsequent packets the filter checks 1686whether the packet matches any state. 1687If it does, the packet is passed without evaluation of any rules. 1688After the connection is closed or times out, the state entry is automatically 1689removed. 1690.Pp 1691This has several advantages. 1692For TCP connections, comparing a packet to a state involves checking 1693its sequence numbers, as well as TCP timestamps if a 1694.Ar scrub reassemble tcp 1695rule applies to the connection. 1696If these values are outside the narrow windows of expected 1697values, the packet is dropped. 1698This prevents spoofing attacks, such as when an attacker sends packets with 1699a fake source address/port but does not know the connection's sequence 1700numbers. 1701Similarly, 1702.Xr pf 4 1703knows how to match ICMP replies to states. 1704For example, 1705.Bd -literal -offset indent 1706pass out inet proto icmp all icmp-type echoreq 1707.Ed 1708.Pp 1709allows echo requests (such as those created by 1710.Xr ping 8 ) 1711out statefully, and matches incoming echo replies correctly to states. 1712.Pp 1713Also, looking up states is usually faster than evaluating rules. 1714.Pp 1715Furthermore, correct handling of ICMP error messages is critical to 1716many protocols, particularly TCP. 1717.Xr pf 4 1718matches ICMP error messages to the correct connection, checks them against 1719connection parameters, and passes them if appropriate. 1720For example if an ICMP source quench message referring to a stateful TCP 1721connection arrives, it will be matched to the state and get passed. 1722.Pp 1723Finally, state tracking is required for 1724.Ar nat , binat No and Ar rdr 1725rules, in order to track address and port translations and reverse the 1726translation on returning packets. 1727.Pp 1728.Xr pf 4 1729will also create state for other protocols which are effectively stateless by 1730nature. 1731UDP packets are matched to states using only host addresses and ports, 1732and other protocols are matched to states using only the host addresses. 1733.Pp 1734If stateless filtering of individual packets is desired, 1735the 1736.Ar no state 1737keyword can be used to specify that state will not be created 1738if this is the last matching rule. 1739A number of parameters can also be set to affect how 1740.Xr pf 4 1741handles state tracking. 1742See 1743.Sx STATEFUL TRACKING OPTIONS 1744below for further details. 1745.Sh PARAMETERS 1746The rule parameters specify the packets to which a rule applies. 1747A packet always comes in on, or goes out through, one interface. 1748Most parameters are optional. 1749If a parameter is specified, the rule only applies to packets with 1750matching attributes. 1751Certain parameters can be expressed as lists, in which case 1752.Xr pfctl 8 1753generates all needed rule combinations. 1754.Bl -tag -width xxxx 1755.It Ar in No or Ar out 1756This rule applies to incoming or outgoing packets. 1757If neither 1758.Ar in 1759nor 1760.Ar out 1761are specified, the rule will match packets in both directions. 1762.It Ar log Pq Cm all | matches | to Ao Ar interface Ac | Cm user 1763In addition to any action specified, 1764log the packet. 1765Only the packet that establishes the state is logged, 1766unless the 1767.Ar no state 1768option is specified. 1769The logged packets are sent to a 1770.Xr pflog 4 1771interface, by default pflog0; 1772pflog0 is monitored by the 1773.Xr pflogd 8 1774logging daemon which logs to the file 1775.Pa /var/log/pflog 1776in 1777.Xr pcap 3 1778binary format. 1779.Pp 1780The keywords 1781.Cm all , matches , to , 1782and 1783.Cm user 1784are optional and can be combined using commas, 1785but must be enclosed in parentheses if given. 1786.Pp 1787Use 1788.Cm all 1789to force logging of all packets for a connection. 1790This is not necessary when 1791.Ar no state 1792is explicitly specified. 1793.Pp 1794If 1795.Cm matches 1796is specified, 1797it logs the packet on all subsequent matching rules. 1798It is often combined with 1799.Cm to Aq Ar interface 1800to avoid adding noise to the default log file. 1801.Pp 1802The keyword 1803.Cm user 1804logs the 1805.Ux 1806user ID of the user that owns the socket and the PID of the process that 1807has the socket open where the packet is sourced from or destined to 1808(depending on which socket is local). 1809This is in addition to the normal information logged. 1810.Pp 1811Only the first packet 1812logged via 1813.Ar log (all, user) 1814will have the user credentials logged when using stateful matching. 1815.Pp 1816To specify a logging interface other than pflog0, 1817use the syntax 1818.Cm to Aq Ar interface . 1819.It Ar quick 1820If a packet matches a rule which has the 1821.Ar quick 1822option set, this rule 1823is considered the last matching rule, and evaluation of subsequent rules 1824is skipped. 1825.It Ar on Aq Ar interface 1826This rule applies only to packets coming in on, or going out through, this 1827particular interface or interface group. 1828For more information on interface groups, 1829see the 1830.Ic group 1831keyword in 1832.Xr ifconfig 8 . 1833.Ar any 1834will match any existing interface except loopback ones. 1835.It Aq Ar af 1836This rule applies only to packets of this address family. 1837Supported values are 1838.Ar inet 1839and 1840.Ar inet6 . 1841.It Ar proto Aq Ar protocol 1842This rule applies only to packets of this protocol. 1843Common protocols are 1844.Xr icmp 4 , 1845.Xr icmp6 4 , 1846.Xr tcp 4 , 1847.Xr sctp 4 , 1848and 1849.Xr udp 4 . 1850For a list of all the protocol name to number mappings used by 1851.Xr pfctl 8 , 1852see the file 1853.Pa /etc/protocols . 1854.It Xo 1855.Ar from Aq Ar source 1856.Ar port Aq Ar source 1857.Ar os Aq Ar source 1858.Ar to Aq Ar dest 1859.Ar port Aq Ar dest 1860.Xc 1861This rule applies only to packets with the specified source and destination 1862addresses and ports. 1863.Pp 1864Addresses can be specified in CIDR notation (matching netblocks), as 1865symbolic host names, interface names or interface group names, or as any 1866of the following keywords: 1867.Pp 1868.Bl -tag -width xxxxxxxxxxxxxx -compact 1869.It Ar any 1870Any address. 1871.It Ar no-route 1872Any address which is not currently routable. 1873.It Ar urpf-failed 1874Any source address that fails a unicast reverse path forwarding (URPF) 1875check, i.e. packets coming in on an interface other than that which holds 1876the route back to the packet's source address. 1877.It Ar self 1878Expands to all addresses assigned to all interfaces. 1879.It Aq Ar table 1880Any address that matches the given table. 1881.El 1882.Pp 1883Ranges of addresses are specified by using the 1884.Sq - 1885operator. 1886For instance: 1887.Dq 10.1.1.10 - 10.1.1.12 1888means all addresses from 10.1.1.10 to 10.1.1.12, 1889hence addresses 10.1.1.10, 10.1.1.11, and 10.1.1.12. 1890.Pp 1891Interface names and interface group names, and 1892.Ar self 1893can have modifiers appended: 1894.Pp 1895.Bl -tag -width xxxxxxxxxxxx -compact 1896.It Ar :network 1897Translates to the network(s) attached to the interface. 1898.It Ar :broadcast 1899Translates to the interface's broadcast address(es). 1900.It Ar :peer 1901Translates to the point-to-point interface's peer address(es). 1902.It Ar :0 1903Do not include interface aliases. 1904.El 1905.Pp 1906Host names may also have the 1907.Ar :0 1908option appended to restrict the name resolution to the first of each 1909v4 and non-link-local v6 address found. 1910.Pp 1911Host name resolution and interface to address translation are done at 1912ruleset load-time. 1913When the address of an interface (or host name) changes (under DHCP or PPP, 1914for instance), the ruleset must be reloaded for the change to be reflected 1915in the kernel. 1916Surrounding the interface name (and optional modifiers) in parentheses 1917changes this behaviour. 1918When the interface name is surrounded by parentheses, the rule is 1919automatically updated whenever the interface changes its address. 1920The ruleset does not need to be reloaded. 1921This is especially useful with 1922.Ar nat . 1923.Pp 1924Ports can be specified either by number or by name. 1925For example, port 80 can be specified as 1926.Em www . 1927For a list of all port name to number mappings used by 1928.Xr pfctl 8 , 1929see the file 1930.Pa /etc/services . 1931.Pp 1932Ports and ranges of ports are specified by using these operators: 1933.Bd -literal -offset indent 1934= (equal) 1935!= (unequal) 1936< (less than) 1937<= (less than or equal) 1938> (greater than) 1939>= (greater than or equal) 1940: (range including boundaries) 1941>< (range excluding boundaries) 1942<> (except range) 1943.Ed 1944.Pp 1945.Sq >< , 1946.Sq <> 1947and 1948.Sq \&: 1949are binary operators (they take two arguments). 1950For instance: 1951.Bl -tag -width Fl 1952.It Ar port 2000:2004 1953means 1954.Sq all ports >= 2000 and <= 2004 , 1955hence ports 2000, 2001, 2002, 2003 and 2004. 1956.It Ar port 2000 >< 2004 1957means 1958.Sq all ports > 2000 and < 2004 , 1959hence ports 2001, 2002 and 2003. 1960.It Ar port 2000 <> 2004 1961means 1962.Sq all ports < 2000 or > 2004 , 1963hence ports 1-1999 and 2005-65535. 1964.El 1965.Pp 1966The operating system of the source host can be specified in the case of TCP 1967rules with the 1968.Ar OS 1969modifier. 1970See the 1971.Sx OPERATING SYSTEM FINGERPRINTING 1972section for more information. 1973.Pp 1974The host, port and OS specifications are optional, as in the following examples: 1975.Bd -literal -offset indent 1976pass in all 1977pass in from any to any 1978pass in proto tcp from any port < 1024 to any 1979pass in proto tcp from any to any port 25 1980pass in proto tcp from 10.0.0.0/8 port >= 1024 \e 1981 to ! 10.1.2.3 port != ssh 1982pass in proto tcp from any os "OpenBSD" 1983.Ed 1984.It Ar all 1985This is equivalent to "from any to any". 1986.It Ar group Aq Ar group 1987Similar to 1988.Ar user , 1989this rule only applies to packets of sockets owned by the specified group. 1990.It Ar user Aq Ar user 1991This rule only applies to packets of sockets owned by the specified user. 1992For outgoing connections initiated from the firewall, this is the user 1993that opened the connection. 1994For incoming connections to the firewall itself, this is the user that 1995listens on the destination port. 1996For forwarded connections, where the firewall is not a connection endpoint, 1997the user and group are 1998.Em unknown . 1999.Pp 2000All packets, both outgoing and incoming, of one connection are associated 2001with the same user and group. 2002Only TCP and UDP packets can be associated with users; for other protocols 2003these parameters are ignored. 2004.Pp 2005User and group refer to the effective (as opposed to the real) IDs, in 2006case the socket is created by a setuid/setgid process. 2007User and group IDs are stored when a socket is created; 2008when a process creates a listening socket as root (for instance, by 2009binding to a privileged port) and subsequently changes to another 2010user ID (to drop privileges), the credentials will remain root. 2011.Pp 2012User and group IDs can be specified as either numbers or names. 2013The syntax is similar to the one for ports. 2014The value 2015.Em unknown 2016matches packets of forwarded connections. 2017.Em unknown 2018can only be used with the operators 2019.Cm = 2020and 2021.Cm != . 2022Other constructs like 2023.Cm user \*(Ge unknown 2024are invalid. 2025Forwarded packets with unknown user and group ID match only rules 2026that explicitly compare against 2027.Em unknown 2028with the operators 2029.Cm = 2030or 2031.Cm != . 2032For instance 2033.Cm user \*(Ge 0 2034does not match forwarded packets. 2035The following example allows only selected users to open outgoing 2036connections: 2037.Bd -literal -offset indent 2038block out proto { tcp, udp } all 2039pass out proto { tcp, udp } all user { < 1000, dhartmei } 2040.Ed 2041.It Xo Ar flags Aq Ar a 2042.Pf / Ns Aq Ar b 2043.No \*(Ba / Ns Aq Ar b 2044.No \*(Ba any 2045.Xc 2046This rule only applies to TCP packets that have the flags 2047.Aq Ar a 2048set out of set 2049.Aq Ar b . 2050Flags not specified in 2051.Aq Ar b 2052are ignored. 2053For stateful connections, the default is 2054.Ar flags S/SA . 2055To indicate that flags should not be checked at all, specify 2056.Ar flags any . 2057The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R. 2058.Bl -tag -width Fl 2059.It Ar flags S/S 2060Flag SYN is set. 2061The other flags are ignored. 2062.It Ar flags S/SA 2063This is the default setting for stateful connections. 2064Out of SYN and ACK, exactly SYN may be set. 2065SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not. 2066This is more restrictive than the previous example. 2067.It Ar flags /SFRA 2068If the first set is not specified, it defaults to none. 2069All of SYN, FIN, RST and ACK must be unset. 2070.El 2071.Pp 2072Because 2073.Ar flags S/SA 2074is applied by default (unless 2075.Ar no state 2076is specified), only the initial SYN packet of a TCP handshake will create 2077a state for a TCP connection. 2078It is possible to be less restrictive, and allow state creation from 2079intermediate 2080.Pq non-SYN 2081packets, by specifying 2082.Ar flags any . 2083This will cause 2084.Xr pf 4 2085to synchronize to existing connections, for instance 2086if one flushes the state table. 2087However, states created from such intermediate packets may be missing 2088connection details such as the TCP window scaling factor. 2089States which modify the packet flow, such as those affected by 2090.Ar af-to , 2091.Ar nat , 2092.Ar binat or 2093.Ar rdr 2094rules, 2095.Ar modulate No or Ar synproxy state 2096options, or scrubbed with 2097.Ar reassemble tcp 2098will also not be recoverable from intermediate packets. 2099Such connections will stall and time out. 2100.It Xo Ar icmp-type Aq Ar type 2101.Ar code Aq Ar code 2102.Xc 2103.It Xo Ar icmp6-type Aq Ar type 2104.Ar code Aq Ar code 2105.Xc 2106This rule only applies to ICMP or ICMPv6 packets with the specified type 2107and code. 2108Text names for ICMP types and codes are listed in 2109.Xr icmp 4 2110and 2111.Xr icmp6 4 . 2112This parameter is only valid for rules that cover protocols ICMP or 2113ICMP6. 2114The protocol and the ICMP type indicator 2115.Po 2116.Ar icmp-type 2117or 2118.Ar icmp6-type 2119.Pc 2120must match. 2121.It Xo Ar tos Aq Ar string 2122.No \*(Ba Aq Ar number 2123.Xc 2124This rule applies to packets with the specified 2125.Em TOS 2126bits set. 2127.Em TOS 2128may be 2129given as one of 2130.Ar critical , 2131.Ar inetcontrol , 2132.Ar lowdelay , 2133.Ar netcontrol , 2134.Ar throughput , 2135.Ar reliability , 2136or one of the DiffServ Code Points: 2137.Ar ef , 2138.Ar va , 2139.Ar af11 No ... Ar af43 , 2140.Ar cs0 No ... Ar cs7 ; 2141or as either hex or decimal. 2142.Pp 2143For example, the following rules are identical: 2144.Bd -literal -offset indent 2145pass all tos lowdelay 2146pass all tos 0x10 2147pass all tos 16 2148.Ed 2149.It Ar allow-opts 2150By default, IPv4 packets with IP options or IPv6 packets with routing 2151extension headers are blocked. 2152When 2153.Ar allow-opts 2154is specified for a 2155.Ar pass 2156rule, packets that pass the filter based on that rule (last matching) 2157do so even if they contain IP options or routing extension headers. 2158For packets that match state, the rule that initially created the 2159state is used. 2160The implicit 2161.Ar pass 2162rule that is used when a packet does not match any rules does not 2163allow IP options. 2164.It Ar label Aq Ar string 2165Adds a label (name) to the rule, which can be used to identify the rule. 2166For instance, 2167pfctl -s labels 2168shows per-rule statistics for rules that have labels. 2169.Pp 2170The following macros can be used in labels: 2171.Pp 2172.Bl -tag -width $srcaddr -compact -offset indent 2173.It Ar $if 2174The interface. 2175.It Ar $srcaddr 2176The source IP address. 2177.It Ar $dstaddr 2178The destination IP address. 2179.It Ar $srcport 2180The source port specification. 2181.It Ar $dstport 2182The destination port specification. 2183.It Ar $proto 2184The protocol name. 2185.It Ar $nr 2186The rule number. 2187.El 2188.Pp 2189For example: 2190.Bd -literal -offset indent 2191ips = \&"{ 1.2.3.4, 1.2.3.5 }\&" 2192pass in proto tcp from any to $ips \e 2193 port > 1023 label \&"$dstaddr:$dstport\&" 2194.Ed 2195.Pp 2196expands to 2197.Bd -literal -offset indent 2198pass in inet proto tcp from any to 1.2.3.4 \e 2199 port > 1023 label \&"1.2.3.4:>1023\&" 2200pass in inet proto tcp from any to 1.2.3.5 \e 2201 port > 1023 label \&"1.2.3.5:>1023\&" 2202.Ed 2203.Pp 2204The macro expansion for the 2205.Ar label 2206directive occurs only at configuration file parse time, not during runtime. 2207.It Ar ridentifier Aq Ar number 2208Add an identifier (number) to the rule, which can be used to correlate the rule 2209to pflog entries, even after ruleset updates. 2210.It Xo Ar queue Aq Ar queue 2211.No \*(Ba ( Aq Ar queue , 2212.Aq Ar queue ) 2213.Xc 2214Packets matching this rule will be assigned to the specified queue. 2215If two queues are given, packets which have a 2216.Em TOS 2217of 2218.Em lowdelay 2219and TCP ACKs with no data payload will be assigned to the second one. 2220See 2221.Sx QUEUEING 2222for setup details. 2223.Pp 2224For example: 2225.Bd -literal -offset indent 2226pass in proto tcp to port 25 queue mail 2227pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio) 2228.Ed 2229.It Cm set prio Ar priority | Pq Ar priority , priority 2230Packets matching this rule will be assigned a specific queueing priority. 2231Priorities are assigned as integers 0 through 7. 2232If the packet is transmitted on a 2233.Xr vlan 4 2234interface, the queueing priority will be written as the priority 2235code point in the 802.1Q VLAN header. 2236If two priorities are given, packets which have a TOS of 2237.Cm lowdelay 2238and TCP ACKs with no data payload will be assigned to the second one. 2239.Pp 2240For example: 2241.Bd -literal -offset indent 2242pass in proto tcp to port 25 set prio 2 2243pass in proto tcp to port 22 set prio (2, 5) 2244.Ed 2245.It Oo Cm \&! Oc Ns Cm received-on Ar interface 2246Only match packets which were received on the specified 2247.Ar interface 2248(or interface group). 2249.Ar any 2250will match any existing interface except loopback ones. 2251.It Ar tag Aq Ar string 2252Packets matching this rule will be tagged with the 2253specified string. 2254The tag acts as an internal marker that can be used to 2255identify these packets later on. 2256This can be used, for example, to provide trust between 2257interfaces and to determine if packets have been 2258processed by translation rules. 2259Tags are 2260.Qq sticky , 2261meaning that the packet will be tagged even if the rule 2262is not the last matching rule. 2263Further matching rules can replace the tag with a 2264new one but will not remove a previously applied tag. 2265A packet is only ever assigned one tag at a time. 2266Packet tagging can be done during 2267.Ar nat , 2268.Ar rdr , 2269.Ar binat 2270or 2271.Ar ether 2272rules in addition to filter rules. 2273Tags take the same macros as labels (see above). 2274.It Ar tagged Aq Ar string 2275Used with filter, translation or scrub rules 2276to specify that packets must already 2277be tagged with the given tag in order to match the rule. 2278.It Ar rtable Aq Ar number 2279Used to select an alternate routing table for the routing lookup. 2280Only effective before the route lookup happened, i.e. when filtering inbound. 2281.It Xo Ar divert-to Aq Ar host 2282.Ar port Aq Ar port 2283.Xc 2284Used to 2285.Xr divert 4 2286packets to the given divert 2287.Ar port . 2288Historically 2289.Ox pf has another meaning for this, and 2290.Fx pf uses 2291this syntax to support 2292.Xr divert 4 instead. Hence, 2293.Ar host 2294has no meaning and can be set to anything like 127.0.0.1. 2295If a packet is re-injected and does not change direction then it will not be 2296re-diverted. 2297.It Ar divert-reply 2298It has no meaning in 2299.Fx pf . 2300.It Ar probability Aq Ar number 2301A probability attribute can be attached to a rule, with a value set between 23020 and 1, bounds not included. 2303In that case, the rule will be honoured using the given probability value 2304only. 2305For example, the following rule will drop 20% of incoming ICMP packets: 2306.Bd -literal -offset indent 2307block in proto icmp probability 20% 2308.Ed 2309.It Ar prio Aq Ar number 2310Only match packets which have the given queueing priority assigned. 2311.El 2312.Sh ROUTING 2313If a packet matches a rule with a route option set, the packet filter will 2314route the packet according to the type of route option. 2315When such a rule creates state, the route option is also applied to all 2316packets matching the same connection. 2317.Bl -tag -width xxxx 2318.It Ar route-to 2319The 2320.Ar route-to 2321option routes the packet to the specified interface with an optional address 2322for the next hop. 2323When a 2324.Ar route-to 2325rule creates state, only packets that pass in the same direction as the 2326filter rule specifies will be routed in this way. 2327Packets passing in the opposite direction (replies) are not affected 2328and are routed normally. 2329.It Ar reply-to 2330The 2331.Ar reply-to 2332option is similar to 2333.Ar route-to , 2334but routes packets that pass in the opposite direction (replies) to the 2335specified interface. 2336Opposite direction is only defined in the context of a state entry, and 2337.Ar reply-to 2338is useful only in rules that create state. 2339It can be used on systems with multiple external connections to 2340route all outgoing packets of a connection through the interface 2341the incoming connection arrived through (symmetric routing enforcement). 2342.It Ar dup-to 2343The 2344.Ar dup-to 2345option creates a duplicate of the packet and routes it like 2346.Ar route-to . 2347The original packet gets routed as it normally would. 2348.El 2349.Sh POOL OPTIONS 2350For 2351.Ar nat 2352and 2353.Ar rdr 2354rules, (as well as for the 2355.Ar route-to , 2356.Ar reply-to 2357and 2358.Ar dup-to 2359rule options) for which there is a single redirection address which has a 2360subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP 2361address), a variety of different methods for assigning this address can be 2362used: 2363.Bl -tag -width xxxx 2364.It Ar bitmask 2365The 2366.Ar bitmask 2367option applies the network portion of the redirection address to the address 2368to be modified (source with 2369.Ar nat , 2370destination with 2371.Ar rdr ) . 2372.It Ar random 2373The 2374.Ar random 2375option selects an address at random within the defined block of addresses. 2376.It Ar source-hash 2377The 2378.Ar source-hash 2379option uses a hash of the source address to determine the redirection address, 2380ensuring that the redirection address is always the same for a given source. 2381An optional key can be specified after this keyword either in hex or as a 2382string; by default 2383.Xr pfctl 8 2384randomly generates a key for source-hash every time the 2385ruleset is reloaded. 2386.It Ar round-robin 2387The 2388.Ar round-robin 2389option loops through the redirection address(es). 2390.Pp 2391When more than one redirection address is specified, 2392.Ar bitmask 2393is not permitted as a pool type. 2394.It Ar static-port 2395With 2396.Ar nat 2397rules, the 2398.Ar static-port 2399option prevents 2400.Xr pf 4 2401from modifying the source port on TCP and UDP packets. 2402.It Xo Ar map-e-portset Aq Ar psid-offset 2403.No / Aq Ar psid-len 2404.No / Aq Ar psid 2405.Xc 2406With 2407.Ar nat 2408rules, the 2409.Ar map-e-portset 2410option enables the source port translation of MAP-E (RFC 7597) Customer Edge. 2411In order to make the host act as a MAP-E Customer Edge, setting up a tunneling 2412interface and pass rules for encapsulated packets are required in addition 2413to the map-e-portset nat rule. 2414.Pp 2415For example: 2416.Bd -literal -offset indent 2417nat on $gif_mape_if from $int_if:network to any \e 2418 -> $ipv4_mape_src map-e-portset 6/8/0x34 2419.Ed 2420.Pp 2421sets PSID offset 6, PSID length 8, PSID 0x34. 2422.It Ar endpoint-independent 2423With 2424.Ar nat 2425rules, the 2426.Ar endpoint-independent 2427option caues 2428.Xr pf 4 2429to always map connections from a UDP source address and port to the same 2430NAT address and port. 2431This feature implements "full-cone" NAT behavior. 2432.El 2433.Pp 2434Additionally, the 2435.Ar sticky-address 2436option can be specified to help ensure that multiple connections from the 2437same source are mapped to the same redirection address. 2438This option can be used with the 2439.Ar random 2440and 2441.Ar round-robin 2442pool options. 2443Note that by default these associations are destroyed as soon as there are 2444no longer states which refer to them; in order to make the mappings last 2445beyond the lifetime of the states, increase the global options with 2446.Ar set timeout src.track . 2447See 2448.Sx STATEFUL TRACKING OPTIONS 2449for more ways to control the source tracking. 2450.Sh STATE MODULATION 2451Much of the security derived from TCP is attributable to how well the 2452initial sequence numbers (ISNs) are chosen. 2453Some popular stack implementations choose 2454.Em very 2455poor ISNs and thus are normally susceptible to ISN prediction exploits. 2456By applying a 2457.Ar modulate state 2458rule to a TCP connection, 2459.Xr pf 4 2460will create a high quality random sequence number for each connection 2461endpoint. 2462.Pp 2463The 2464.Ar modulate state 2465directive implicitly keeps state on the rule and is 2466only applicable to TCP connections. 2467.Pp 2468For instance: 2469.Bd -literal -offset indent 2470block all 2471pass out proto tcp from any to any modulate state 2472pass in proto tcp from any to any port 25 flags S/SFRA modulate state 2473.Ed 2474.Pp 2475Note that modulated connections will not recover when the state table 2476is lost (firewall reboot, flushing the state table, etc...). 2477.Xr pf 4 2478will not be able to infer a connection again after the state table flushes 2479the connection's modulator. 2480When the state is lost, the connection may be left dangling until the 2481respective endpoints time out the connection. 2482It is possible on a fast local network for the endpoints to start an ACK 2483storm while trying to resynchronize after the loss of the modulator. 2484The default 2485.Ar flags 2486settings (or a more strict equivalent) should be used on 2487.Ar modulate state 2488rules to prevent ACK storms. 2489.Pp 2490Note that alternative methods are available 2491to prevent loss of the state table 2492and allow for firewall failover. 2493See 2494.Xr carp 4 2495and 2496.Xr pfsync 4 2497for further information. 2498.Sh SYN PROXY 2499By default, 2500.Xr pf 4 2501passes packets that are part of a 2502.Xr tcp 4 2503handshake between the endpoints. 2504The 2505.Ar synproxy state 2506option can be used to cause 2507.Xr pf 4 2508itself to complete the handshake with the active endpoint, perform a handshake 2509with the passive endpoint, and then forward packets between the endpoints. 2510.Pp 2511No packets are sent to the passive endpoint before the active endpoint has 2512completed the handshake, hence so-called SYN floods with spoofed source 2513addresses will not reach the passive endpoint, as the sender can't complete the 2514handshake. 2515.Pp 2516The proxy is transparent to both endpoints, they each see a single 2517connection from/to the other endpoint. 2518.Xr pf 4 2519chooses random initial sequence numbers for both handshakes. 2520Once the handshakes are completed, the sequence number modulators 2521(see previous section) are used to translate further packets of the 2522connection. 2523.Ar synproxy state 2524includes 2525.Ar modulate state . 2526.Pp 2527Rules with 2528.Ar synproxy 2529will not work if 2530.Xr pf 4 2531operates on a 2532.Xr bridge 4 . 2533.Pp 2534Example: 2535.Bd -literal -offset indent 2536pass in proto tcp from any to any port www synproxy state 2537.Ed 2538.Sh STATEFUL TRACKING OPTIONS 2539A number of options related to stateful tracking can be applied on a 2540per-rule basis. 2541.Ar keep state , 2542.Ar modulate state 2543and 2544.Ar synproxy state 2545support these options, and 2546.Ar keep state 2547must be specified explicitly to apply options to a rule. 2548.Pp 2549.Bl -tag -width xxxx -compact 2550.It Ar max Aq Ar number 2551Limits the number of concurrent states the rule may create. 2552When this limit is reached, further packets that would create 2553state are dropped until existing states time out. 2554.It Ar no-sync 2555Prevent state changes for states created by this rule from appearing on the 2556.Xr pfsync 4 2557interface. 2558.It Xo Aq Ar timeout 2559.Aq Ar seconds 2560.Xc 2561Changes the timeout values used for states created by this rule. 2562For a list of all valid timeout names, see 2563.Sx OPTIONS 2564above. 2565.It Ar sloppy 2566Uses a sloppy TCP connection tracker that does not check sequence 2567numbers at all, which makes insertion and ICMP teardown attacks way 2568easier. 2569This is intended to be used in situations where one does not see all 2570packets of a connection, e.g. in asymmetric routing situations. 2571Cannot be used with modulate or synproxy state. 2572.It Ar pflow 2573States created by this rule are exported on the 2574.Xr pflow 4 2575interface. 2576.It Ar allow-related 2577Automatically allow connections related to this one, regardless of rules that 2578might otherwise affect them. 2579This currently only applies to SCTP multihomed connection. 2580.El 2581.Pp 2582Multiple options can be specified, separated by commas: 2583.Bd -literal -offset indent 2584pass in proto tcp from any to any \e 2585 port www keep state \e 2586 (max 100, source-track rule, max-src-nodes 75, \e 2587 max-src-states 3, tcp.established 60, tcp.closing 5) 2588.Ed 2589.Pp 2590When the 2591.Ar source-track 2592keyword is specified, the number of states per source IP is tracked. 2593.Pp 2594.Bl -tag -width xxxx -compact 2595.It Ar source-track rule 2596The maximum number of states created by this rule is limited by the rule's 2597.Ar max-src-nodes 2598and 2599.Ar max-src-states 2600options. 2601Only state entries created by this particular rule count toward the rule's 2602limits. 2603.It Ar source-track global 2604The number of states created by all rules that use this option is limited. 2605Each rule can specify different 2606.Ar max-src-nodes 2607and 2608.Ar max-src-states 2609options, however state entries created by any participating rule count towards 2610each individual rule's limits. 2611.El 2612.Pp 2613The following limits can be set: 2614.Pp 2615.Bl -tag -width xxxx -compact 2616.It Ar max-src-nodes Aq Ar number 2617Limits the maximum number of source addresses which can simultaneously 2618have state table entries. 2619.It Ar max-src-states Aq Ar number 2620Limits the maximum number of simultaneous state entries that a single 2621source address can create with this rule. 2622.El 2623.Pp 2624For stateful TCP connections, limits on established connections (connections 2625which have completed the TCP 3-way handshake) can also be enforced 2626per source IP. 2627.Pp 2628.Bl -tag -width xxxx -compact 2629.It Ar max-src-conn Aq Ar number 2630Limits the maximum number of simultaneous TCP connections which have 2631completed the 3-way handshake that a single host can make. 2632.It Xo Ar max-src-conn-rate Aq Ar number 2633.No / Aq Ar seconds 2634.Xc 2635Limit the rate of new connections over a time interval. 2636The connection rate is an approximation calculated as a moving average. 2637.El 2638.Pp 2639When one of these limits is reached, further packets that would create 2640state are dropped until existing states time out. 2641.Pp 2642Because the 3-way handshake ensures that the source address is not being 2643spoofed, more aggressive action can be taken based on these limits. 2644With the 2645.Ar overload Aq Ar table 2646state option, source IP addresses which hit either of the limits on 2647established connections will be added to the named table. 2648This table can be used in the ruleset to block further activity from 2649the offending host, redirect it to a tarpit process, or restrict its 2650bandwidth. 2651.Pp 2652The optional 2653.Ar flush 2654keyword kills all states created by the matching rule which originate 2655from the host which exceeds these limits. 2656The 2657.Ar global 2658modifier to the flush command kills all states originating from the 2659offending host, regardless of which rule created the state. 2660.Pp 2661For example, the following rules will protect the webserver against 2662hosts making more than 100 connections in 10 seconds. 2663Any host which connects faster than this rate will have its address added 2664to the 2665.Aq bad_hosts 2666table and have all states originating from it flushed. 2667Any new packets arriving from this host will be dropped unconditionally 2668by the block rule. 2669.Bd -literal -offset indent 2670block quick from <bad_hosts> 2671pass in on $ext_if proto tcp to $webserver port www keep state \e 2672 (max-src-conn-rate 100/10, overload <bad_hosts> flush global) 2673.Ed 2674.Sh OPERATING SYSTEM FINGERPRINTING 2675Passive OS Fingerprinting is a mechanism to inspect nuances of a TCP 2676connection's initial SYN packet and guess at the host's operating system. 2677Unfortunately these nuances are easily spoofed by an attacker so the 2678fingerprint is not useful in making security decisions. 2679But the fingerprint is typically accurate enough to make policy decisions 2680upon. 2681.Pp 2682The fingerprints may be specified by operating system class, by 2683version, or by subtype/patchlevel. 2684The class of an operating system is typically the vendor or genre 2685and would be 2686.Ox 2687for the 2688.Xr pf 4 2689firewall itself. 2690The version of the oldest available 2691.Ox 2692release on the main FTP site 2693would be 2.6 and the fingerprint would be written 2694.Pp 2695.Dl \&"OpenBSD 2.6\&" 2696.Pp 2697The subtype of an operating system is typically used to describe the 2698patchlevel if that patch led to changes in the TCP stack behavior. 2699In the case of 2700.Ox , 2701the only subtype is for a fingerprint that was 2702normalized by the 2703.Ar no-df 2704scrub option and would be specified as 2705.Pp 2706.Dl \&"OpenBSD 3.3 no-df\&" 2707.Pp 2708Fingerprints for most popular operating systems are provided by 2709.Xr pf.os 5 . 2710Once 2711.Xr pf 4 2712is running, a complete list of known operating system fingerprints may 2713be listed by running: 2714.Pp 2715.Dl # pfctl -so 2716.Pp 2717Filter rules can enforce policy at any level of operating system specification 2718assuming a fingerprint is present. 2719Policy could limit traffic to approved operating systems or even ban traffic 2720from hosts that aren't at the latest service pack. 2721.Pp 2722The 2723.Ar unknown 2724class can also be used as the fingerprint which will match packets for 2725which no operating system fingerprint is known. 2726.Pp 2727Examples: 2728.Bd -literal -offset indent 2729pass out proto tcp from any os OpenBSD 2730block out proto tcp from any os Doors 2731block out proto tcp from any os "Doors PT" 2732block out proto tcp from any os "Doors PT SP3" 2733block out from any os "unknown" 2734pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" 2735.Ed 2736.Pp 2737Operating system fingerprinting is limited only to the TCP SYN packet. 2738This means that it will not work on other protocols and will not match 2739a currently established connection. 2740.Pp 2741Caveat: operating system fingerprints are occasionally wrong. 2742There are three problems: an attacker can trivially craft his packets to 2743appear as any operating system he chooses; 2744an operating system patch could change the stack behavior and no fingerprints 2745will match it until the database is updated; 2746and multiple operating systems may have the same fingerprint. 2747.Sh BLOCKING SPOOFED TRAFFIC 2748"Spoofing" is the faking of IP addresses, typically for malicious 2749purposes. 2750The 2751.Ar antispoof 2752directive expands to a set of filter rules which will block all 2753traffic with a source IP from the network(s) directly connected 2754to the specified interface(s) from entering the system through 2755any other interface. 2756.Pp 2757For example, the line 2758.Bd -literal -offset indent 2759antispoof for lo0 2760.Ed 2761.Pp 2762expands to 2763.Bd -literal -offset indent 2764block drop in on ! lo0 inet from 127.0.0.1/8 to any 2765block drop in on ! lo0 inet6 from ::1 to any 2766.Ed 2767.Pp 2768For non-loopback interfaces, there are additional rules to block incoming 2769packets with a source IP address identical to the interface's IP(s). 2770For example, assuming the interface wi0 had an IP address of 10.0.0.1 and a 2771netmask of 255.255.255.0, 2772the line 2773.Bd -literal -offset indent 2774antispoof for wi0 inet 2775.Ed 2776.Pp 2777expands to 2778.Bd -literal -offset indent 2779block drop in on ! wi0 inet from 10.0.0.0/24 to any 2780block drop in inet from 10.0.0.1 to any 2781.Ed 2782.Pp 2783Caveat: Rules created by the 2784.Ar antispoof 2785directive interfere with packets sent over loopback interfaces 2786to local addresses. 2787One should pass these explicitly. 2788.Sh FRAGMENT HANDLING 2789The size of IP datagrams (packets) can be significantly larger than the 2790maximum transmission unit (MTU) of the network. 2791In cases when it is necessary or more efficient to send such large packets, 2792the large packet will be fragmented into many smaller packets that will each 2793fit onto the wire. 2794Unfortunately for a firewalling device, only the first logical fragment will 2795contain the necessary header information for the subprotocol that allows 2796.Xr pf 4 2797to filter on things such as TCP ports or to perform NAT. 2798.Pp 2799Besides the use of 2800.Ar set reassemble 2801option or 2802.Ar scrub 2803rules as described in 2804.Sx TRAFFIC NORMALIZATION 2805above, there are three options for handling fragments in the packet filter. 2806.Pp 2807One alternative is to filter individual fragments with filter rules. 2808If no 2809.Ar scrub 2810rule applies to a fragment or 2811.Ar set reassemble 2812is set to 2813.Cm no 2814, it is passed to the filter. 2815Filter rules with matching IP header parameters decide whether the 2816fragment is passed or blocked, in the same way as complete packets 2817are filtered. 2818Without reassembly, fragments can only be filtered based on IP header 2819fields (source/destination address, protocol), since subprotocol header 2820fields are not available (TCP/UDP port numbers, ICMP code/type). 2821The 2822.Ar fragment 2823option can be used to restrict filter rules to apply only to 2824fragments, but not complete packets. 2825Filter rules without the 2826.Ar fragment 2827option still apply to fragments, if they only specify IP header fields. 2828For instance, the rule 2829.Bd -literal -offset indent 2830pass in proto tcp from any to any port 80 2831.Ed 2832.Pp 2833never applies to a fragment, even if the fragment is part of a TCP 2834packet with destination port 80, because without reassembly this information 2835is not available for each fragment. 2836This also means that fragments cannot create new or match existing 2837state table entries, which makes stateful filtering and address 2838translation (NAT, redirection) for fragments impossible. 2839.Pp 2840It's also possible to reassemble only certain fragments by specifying 2841source or destination addresses or protocols as parameters in 2842.Ar scrub 2843rules. 2844.Pp 2845In most cases, the benefits of reassembly outweigh the additional 2846memory cost, and it's recommended to use 2847.Ar set reassemble 2848option or 2849.Ar scrub 2850rules with the 2851.Ar fragment reassemble 2852modifier to reassemble 2853all fragments. 2854.Pp 2855The memory allocated for fragment caching can be limited using 2856.Xr pfctl 8 . 2857Once this limit is reached, fragments that would have to be cached 2858are dropped until other entries time out. 2859The timeout value can also be adjusted. 2860.Pp 2861When forwarding reassembled IPv6 packets, pf refragments them with 2862the original maximum fragment size. 2863This allows the sender to determine the optimal fragment size by 2864path MTU discovery. 2865.Sh ANCHORS 2866Besides the main ruleset, 2867.Xr pfctl 8 2868can load rulesets into 2869.Ar anchor 2870attachment points. 2871An 2872.Ar anchor 2873is a container that can hold rules, address tables, and other anchors. 2874.Pp 2875An 2876.Ar anchor 2877has a name which specifies the path where 2878.Xr pfctl 8 2879can be used to access the anchor to perform operations on it, such as 2880attaching child anchors to it or loading rules into it. 2881Anchors may be nested, with components separated by 2882.Sq / 2883characters, similar to how file system hierarchies are laid out. 2884The main ruleset is actually the default anchor, so filter and 2885translation rules, for example, may also be contained in any anchor. 2886.Pp 2887An anchor can reference another 2888.Ar anchor 2889attachment point 2890using the following kinds 2891of rules: 2892.Bl -tag -width xxxx 2893.It Ar nat-anchor Aq Ar name 2894Evaluates the 2895.Ar nat 2896rules in the specified 2897.Ar anchor . 2898.It Ar rdr-anchor Aq Ar name 2899Evaluates the 2900.Ar rdr 2901rules in the specified 2902.Ar anchor . 2903.It Ar binat-anchor Aq Ar name 2904Evaluates the 2905.Ar binat 2906rules in the specified 2907.Ar anchor . 2908.It Ar anchor Aq Ar name 2909Evaluates the filter rules in the specified 2910.Ar anchor . 2911.It Xo Ar load anchor 2912.Aq Ar name 2913.Ar from Aq Ar file 2914.Xc 2915Loads the rules from the specified file into the 2916anchor 2917.Ar name . 2918.El 2919.Pp 2920When evaluation of the main ruleset reaches an 2921.Ar anchor 2922rule, 2923.Xr pf 4 2924will proceed to evaluate all rules specified in that anchor. 2925.Pp 2926Matching filter and translation rules marked with the 2927.Ar quick 2928option are final and abort the evaluation of the rules in other 2929anchors and the main ruleset. 2930If the 2931.Ar anchor 2932itself is marked with the 2933.Ar quick 2934option, 2935ruleset evaluation will terminate when the anchor is exited if the packet is 2936matched by any rule within the anchor. 2937.Pp 2938.Ar anchor 2939rules are evaluated relative to the anchor in which they are contained. 2940For example, all 2941.Ar anchor 2942rules specified in the main ruleset will reference anchor 2943attachment points underneath the main ruleset, and 2944.Ar anchor 2945rules specified in a file loaded from a 2946.Ar load anchor 2947rule will be attached under that anchor point. 2948.Pp 2949Rules may be contained in 2950.Ar anchor 2951attachment points which do not contain any rules when the main ruleset 2952is loaded, and later such anchors can be manipulated through 2953.Xr pfctl 8 2954without reloading the main ruleset or other anchors. 2955For example, 2956.Bd -literal -offset indent 2957ext_if = \&"kue0\&" 2958block on $ext_if all 2959anchor spam 2960pass out on $ext_if all 2961pass in on $ext_if proto tcp from any \e 2962 to $ext_if port smtp 2963.Ed 2964.Pp 2965blocks all packets on the external interface by default, then evaluates 2966all rules in the 2967.Ar anchor 2968named "spam", and finally passes all outgoing connections and 2969incoming connections to port 25. 2970.Bd -literal -offset indent 2971# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e 2972 pfctl -a spam -f - 2973.Ed 2974.Pp 2975This loads a single rule into the 2976.Ar anchor , 2977which blocks all packets from a specific address. 2978.Pp 2979The anchor can also be populated by adding a 2980.Ar load anchor 2981rule after the 2982.Ar anchor 2983rule: 2984.Bd -literal -offset indent 2985anchor spam 2986load anchor spam from "/etc/pf-spam.conf" 2987.Ed 2988.Pp 2989When 2990.Xr pfctl 8 2991loads 2992.Nm pf.conf , 2993it will also load all the rules from the file 2994.Pa /etc/pf-spam.conf 2995into the anchor. 2996.Pp 2997Optionally, 2998.Ar anchor 2999rules can specify packet filtering parameters using the same syntax as 3000filter rules. 3001When parameters are used, the 3002.Ar anchor 3003rule is only evaluated for matching packets. 3004This allows conditional evaluation of anchors, like: 3005.Bd -literal -offset indent 3006block on $ext_if all 3007anchor spam proto tcp from any to any port smtp 3008pass out on $ext_if all 3009pass in on $ext_if proto tcp from any to $ext_if port smtp 3010.Ed 3011.Pp 3012The rules inside 3013.Ar anchor 3014spam are only evaluated for 3015.Ar tcp 3016packets with destination port 25. 3017Hence, 3018.Bd -literal -offset indent 3019# echo \&"block in quick from 1.2.3.4 to any" \&| \e 3020 pfctl -a spam -f - 3021.Ed 3022.Pp 3023will only block connections from 1.2.3.4 to port 25. 3024.Pp 3025Anchors may end with the asterisk 3026.Pq Sq * 3027character, which signifies that all anchors attached at that point 3028should be evaluated in the alphabetical ordering of their anchor name. 3029For example, 3030.Bd -literal -offset indent 3031anchor "spam/*" 3032.Ed 3033.Pp 3034will evaluate each rule in each anchor attached to the 3035.Li spam 3036anchor. 3037Note that it will only evaluate anchors that are directly attached to the 3038.Li spam 3039anchor, and will not descend to evaluate anchors recursively. 3040.Pp 3041Since anchors are evaluated relative to the anchor in which they are 3042contained, there is a mechanism for accessing the parent and ancestor 3043anchors of a given anchor. 3044Similar to file system path name resolution, if the sequence 3045.Dq .. 3046appears as an anchor path component, the parent anchor of the current 3047anchor in the path evaluation at that point will become the new current 3048anchor. 3049As an example, consider the following: 3050.Bd -literal -offset indent 3051# echo ' anchor "spam/allowed" ' | pfctl -f - 3052# echo -e ' anchor "../banned" \en pass' | \e 3053 pfctl -a spam/allowed -f - 3054.Ed 3055.Pp 3056Evaluation of the main ruleset will lead into the 3057.Li spam/allowed 3058anchor, which will evaluate the rules in the 3059.Li spam/banned 3060anchor, if any, before finally evaluating the 3061.Ar pass 3062rule. 3063.Pp 3064Filter rule 3065.Ar anchors 3066can also be loaded inline in the ruleset within a brace ('{' '}') delimited 3067block. 3068Brace delimited blocks may contain rules or other brace-delimited blocks. 3069When anchors are loaded this way the anchor name becomes optional. 3070.Bd -literal -offset indent 3071anchor "external" on $ext_if { 3072 block 3073 anchor out { 3074 pass proto tcp from any to port { 25, 80, 443 } 3075 } 3076 pass in proto tcp to any port 22 3077} 3078.Ed 3079.Pp 3080Since the parser specification for anchor names is a string, any 3081reference to an anchor name containing 3082.Sq / 3083characters will require double quote 3084.Pq Sq \&" 3085characters around the anchor name. 3086.Sh SCTP CONSIDERATIONS 3087.Xr pf 4 3088supports 3089.Xr sctp 4 3090connections. 3091It can match ports, track state and NAT SCTP traffic. 3092However, it will not alter port numbers during nat or rdr translations. 3093Doing so would break SCTP multihoming. 3094.Sh TRANSLATION EXAMPLES 3095This example maps incoming requests on port 80 to port 8080, on 3096which a daemon is running (because, for example, it is not run as root, 3097and therefore lacks permission to bind to port 80). 3098.Bd -literal -offset indent 3099# use a macro for the interface name, so it can be changed easily 3100ext_if = \&"ne3\&" 3101 3102# map daemon on 8080 to appear to be on 80 3103match in on $ext_if proto tcp from any to any port 80 \e 3104 rdr-to 127.0.0.1 port 8080 3105.Ed 3106.Pp 3107If a 3108.Ar pass 3109rule is used with the 3110.Ar quick 3111modifier, packets matching the translation rule are passed without 3112inspecting subsequent filter rules: 3113.Bd -literal -offset indent 3114pass in quick on $ext_if proto tcp from any to any port 80 \e 3115 rdr-to 127.0.0.1 port 8080 3116.Ed 3117.Pp 3118In the example below, vlan12 is configured as 192.168.168.1; 3119the machine translates all packets coming from 192.168.168.0/24 to 204.92.77.111 3120when they are going out any interface except vlan12. 3121This has the net effect of making traffic from the 192.168.168.0/24 3122network appear as though it is the Internet routable address 3123204.92.77.111 to nodes behind any interface on the router except 3124for the nodes on vlan12. 3125(Thus, 192.168.168.1 can talk to the 192.168.168.0/24 nodes.) 3126.Bd -literal -offset indent 3127match out on ! vlan12 from 192.168.168.0/24 to any nat-to 204.92.77.111 3128.Ed 3129.Pp 3130This longer example uses both a NAT and a redirection. 3131The external interface has the address 157.161.48.183. 3132On localhost, we are running 3133.Xr ftp-proxy 8 , 3134waiting for FTP sessions to be redirected to it. 3135The three mandatory anchors for 3136.Xr ftp-proxy 8 3137are omitted from this example; see the 3138.Xr ftp-proxy 8 3139manpage. 3140.Bd -literal -offset indent 3141# NAT 3142# Translate outgoing packets' source addresses (any protocol). 3143# In this case, any address but the gateway's external address is mapped. 3144pass out on $ext_if inet from ! ($ext_if) to any nat-to ($ext_if) 3145 3146# NAT PROXYING 3147# Map outgoing packets' source port to an assigned proxy port instead of 3148# an arbitrary port. 3149# In this case, proxy outgoing isakmp with port 500 on the gateway. 3150pass out on $ext_if inet proto udp from any port = isakmp to any \e 3151 nat-to ($ext_if) port 500 3152 3153# BINAT 3154# Translate outgoing packets' source address (any protocol). 3155# Translate incoming packets' destination address to an internal machine 3156# (bidirectional). 3157pass on $ext_if from 10.1.2.150 to any binat-to $ext_if 3158 3159# Translate packets arriving on $peer_if addressed to 172.22.16.0/20 3160# to the corresponding address in 172.21.16.0/20 (bidirectional). 3161pass on $peer_if from 172.21.16.0/20 to any binat-to 172.22.16.0/20 3162 3163# RDR 3164# Translate incoming packets' destination addresses. 3165# As an example, redirect a TCP and UDP port to an internal machine. 3166pass in on $ext_if inet proto tcp from any to ($ext_if) port 8080 \e 3167 rdr-to 10.1.2.151 port 22 3168pass in on $ext_if inet proto udp from any to ($ext_if) port 8080 \e 3169 rdr-to 10.1.2.151 port 53 3170 3171# RDR 3172# Translate outgoing ftp control connections to send them to localhost 3173# for proxying with ftp-proxy(8) running on port 8021. 3174pass in on $int_if proto tcp from any to any port 21 \e 3175 rdr-to 127.0.0.1 port 8021 3176.Ed 3177.Pp 3178In this example, a NAT gateway is set up to translate internal addresses 3179using a pool of public addresses (192.0.2.16/28) and to redirect 3180incoming web server connections to a group of web servers on the internal 3181network. 3182.Bd -literal -offset indent 3183# NAT LOAD BALANCE 3184# Translate outgoing packets' source addresses using an address pool. 3185# A given source address is always translated to the same pool address by 3186# using the source-hash keyword. 3187pass out on $ext_if inet from any to any nat-to 192.0.2.16/28 source-hash 3188 3189# RDR ROUND ROBIN 3190# Translate incoming web server connections to a group of web servers on 3191# the internal network. 3192pass in on $ext_if proto tcp from any to any port 80 \e 3193 rdr-to { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin 3194.Ed 3195.Sh COMPATIBILITY TRANSLATION EXAMPLES 3196In the example below, the machine sits between a fake internal 144.19.74.* 3197network, and a routable external IP of 204.92.77.100. 3198The 3199.Ar no nat 3200rule excludes protocol AH from being translated. 3201.Bd -literal -offset indent 3202# NAT 3203no nat on $ext_if proto ah from 144.19.74.0/24 to any 3204nat on $ext_if from 144.19.74.0/24 to any -> 204.92.77.100 3205.Ed 3206.Pp 3207In the example below, packets bound for one specific server, as well as those 3208generated by the sysadmins are not proxied; all other connections are. 3209.Bd -literal -offset indent 3210# RDR 3211no rdr on $int_if proto { tcp, udp } from any to $server port 80 3212no rdr on $int_if proto { tcp, udp } from $sysadmins to any port 80 3213rdr on $int_if proto { tcp, udp } from any to any port 80 \e 3214 -> 127.0.0.1 port 80 3215.Ed 3216.Sh FILTER EXAMPLES 3217.Bd -literal -offset indent 3218# The external interface is kue0 3219# (157.161.48.183, the only routable address) 3220# and the private network is 10.0.0.0/8, for which we are doing NAT. 3221 3222# Reassemble incoming traffic 3223set reassemble yes 3224 3225# use a macro for the interface name, so it can be changed easily 3226ext_if = \&"kue0\&" 3227 3228# block and log everything by default 3229block return log on $ext_if all 3230 3231# block anything coming from source we have no back routes for 3232block in from no-route to any 3233 3234# block packets whose ingress interface does not match the one in 3235# the route back to their source address 3236block in from urpf-failed to any 3237 3238# block and log outgoing packets that do not have our address as source, 3239# they are either spoofed or something is misconfigured (NAT disabled, 3240# for instance), we want to be nice and do not send out garbage. 3241block out log quick on $ext_if from ! 157.161.48.183 to any 3242 3243# silently drop broadcasts (cable modem noise) 3244block in quick on $ext_if from any to 255.255.255.255 3245 3246# block and log incoming packets from reserved address space and invalid 3247# addresses, they are either spoofed or misconfigured, we cannot reply to 3248# them anyway (hence, no return-rst). 3249block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e 3250 192.168.0.0/16, 255.255.255.255/32 } to any 3251 3252# ICMP 3253 3254# pass out/in certain ICMP queries and keep state (ping) 3255# state matching is done on host addresses and ICMP id (not type/code), 3256# so replies (like 0/0 for 8/0) will match queries 3257# ICMP error messages (which always refer to a TCP/UDP packet) are 3258# handled by the TCP/UDP states 3259pass on $ext_if inet proto icmp all icmp-type 8 code 0 3260 3261# UDP 3262 3263# pass out all UDP connections and keep state 3264pass out on $ext_if proto udp all 3265 3266# pass in certain UDP connections and keep state (DNS) 3267pass in on $ext_if proto udp from any to any port domain 3268 3269# TCP 3270 3271# pass out all TCP connections and modulate state 3272pass out on $ext_if proto tcp all modulate state 3273 3274# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT) 3275pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e 3276 auth } 3277 3278# Do not allow Windows 9x SMTP connections since they are typically 3279# a viral worm. Alternately we could limit these OSes to 1 connection each. 3280block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e 3281 to any port smtp 3282 3283# IPv6 3284# pass in/out all IPv6 traffic: note that we have to enable this in two 3285# different ways, on both our physical interface and our tunnel 3286pass quick on gif0 inet6 3287pass quick on $ext_if proto ipv6 3288 3289# Packet Tagging 3290 3291# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is 3292# being done on $ext_if for all outgoing packets. tag packets in on 3293# $int_if and pass those tagged packets out on $ext_if. all other 3294# outgoing packets (i.e., packets from the wireless network) are only 3295# permitted to access port 80. 3296 3297pass in on $int_if from any to any tag INTNET 3298pass in on $wifi_if from any to any 3299 3300block out on $ext_if from any to any 3301pass out quick on $ext_if tagged INTNET 3302pass out on $ext_if proto tcp from any to any port 80 3303 3304# tag incoming packets as they are redirected to spamd(8). use the tag 3305# to pass those packets through the packet filter. 3306 3307rdr on $ext_if inet proto tcp from <spammers> to port smtp \e 3308 tag SPAMD -> 127.0.0.1 port spamd 3309 3310block in on $ext_if 3311pass in on $ext_if inet proto tcp tagged SPAMD 3312.Ed 3313.Pp 3314In the example below, a router handling both address families 3315translates an internal IPv4 subnet to IPv6 using the well-known 331664:ff9b::/96 prefix: 3317.Bd -literal -offset 4n 3318pass in on $v4_if inet af-to inet6 from ($v6_if) to 64:ff9b::/96 3319.Ed 3320.Pp 3321Paired with the example above, the example below can be used on 3322another router handling both address families to translate back 3323to IPv4: 3324.Bd -literal -offset 4n 3325pass in on $v6_if inet6 to 64:ff9b::/96 af-to inet from ($v4_if) 3326.Ed 3327.Sh GRAMMAR 3328Syntax for 3329.Nm 3330in BNF: 3331.Bd -literal 3332line = ( option | ether-rule | pf-rule | nat-rule | binat-rule | 3333 rdr-rule | antispoof-rule | altq-rule | queue-rule | 3334 trans-anchors | anchor-rule | anchor-close | load-anchor | 3335 table-rule | include ) 3336 3337option = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] | 3338 [ "ruleset-optimization" [ "none" | "basic" | "profile" ]] | 3339 [ "optimization" [ "default" | "normal" | 3340 "high-latency" | "satellite" | 3341 "aggressive" | "conservative" ] ] 3342 [ "limit" ( limit-item | "{" limit-list "}" ) ] | 3343 [ "loginterface" ( interface-name | "none" ) ] | 3344 [ "block-policy" ( "drop" | "return" ) ] | 3345 [ "state-policy" ( "if-bound" | "floating" ) ] 3346 [ "state-defaults" state-opts ] 3347 [ "require-order" ( "yes" | "no" ) ] 3348 [ "fingerprints" filename ] | 3349 [ "skip on" ifspec ] | 3350 [ "debug" ( "none" | "urgent" | "misc" | "loud" ) ] 3351 [ "keepcounters" ] ) 3352 3353ether-rule = "ether" etheraction [ ( "in" | "out" ) ] 3354 [ "quick" ] [ "on" ifspec ] [ "bridge-to" interface-name ] 3355 [ etherprotospec ] [ etherhosts ] [ "l3" hosts ] 3356 [ etherfilteropt-list ] 3357 3358pf-rule = action [ ( "in" | "out" ) ] 3359 [ "log" [ "(" logopts ")"] ] [ "quick" ] 3360 [ "on" ifspec ] [ route ] [ af ] [ protospec ] 3361 [ hosts ] [ filteropt-list ] 3362 3363logopts = logopt [ "," logopts ] 3364logopt = "all" | "matches" | "user" | "to" interface-name 3365 3366etherfilteropt-list = etherfilteropt-list etherfilteropt | etherfilteropt 3367etherfilteropt = "tag" string | "tagged" string | "queue" ( string ) | 3368 "ridentifier" number | "label" string 3369 3370filteropt-list = filteropt-list filteropt | filteropt 3371filteropt = user | group | flags | icmp-type | icmp6-type | "tos" tos | 3372 "af-to" af "from" ( redirhost | "{" redirhost-list "}" ) 3373 [ "to" ( redirhost | "{" redirhost-list "}" ) ] | 3374 ( "no" | "keep" | "modulate" | "synproxy" ) "state" 3375 [ "(" state-opts ")" ] | 3376 "fragment" | "no-df" | "min-ttl" number | "set-tos" tos | 3377 "max-mss" number | "random-id" | "reassemble tcp" | 3378 fragmentation | "allow-opts" | 3379 "label" string | "tag" string | [ "!" ] "tagged" string | 3380 "set prio" ( number | "(" number [ [ "," ] number ] ")" ) | 3381 "queue" ( string | "(" string [ [ "," ] string ] ")" ) | 3382 "rtable" number | "probability" number"%" | "prio" number | 3383 "dnpipe" ( number | "(" number "," number ")" ) | 3384 "dnqueue" ( number | "(" number "," number ")" ) | 3385 "ridentifier" number | 3386 [ ! ] "received-on" ( interface-name | interface-group ) 3387 3388nat-rule = [ "no" ] "nat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 3389 [ "on" ifspec ] [ af ] 3390 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 3391 [ "->" ( redirhost | "{" redirhost-list "}" ) 3392 [ portspec ] [ pooltype ] [ "static-port" ] 3393 [ "map-e-portset" number "/" number "/" number ] ] 3394 3395binat-rule = [ "no" ] "binat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 3396 [ "on" interface-name ] [ af ] 3397 [ "proto" ( proto-name | proto-number ) ] 3398 "from" address [ "/" mask-bits ] "to" ipspec 3399 [ "tag" string ] [ "tagged" string ] 3400 [ "->" address [ "/" mask-bits ] ] 3401 3402rdr-rule = [ "no" ] "rdr" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 3403 [ "on" ifspec ] [ af ] 3404 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 3405 [ "->" ( redirhost | "{" redirhost-list "}" ) 3406 [ portspec ] [ pooltype ] ] 3407 3408antispoof-rule = "antispoof" [ "log" ] [ "quick" ] 3409 "for" ifspec [ af ] [ "label" string ] 3410 [ "ridentifier" number ] 3411 3412table-rule = "table" "<" string ">" [ tableopts-list ] 3413tableopts-list = tableopts-list tableopts | tableopts 3414tableopts = "persist" | "const" | "counters" | "file" string | 3415 "{" [ tableaddr-list ] "}" 3416tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec 3417tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ] 3418tableaddr = hostname | ifspec | "self" | 3419 ipv4-dotted-quad | ipv6-coloned-hex 3420 3421altq-rule = "altq on" interface-name queueopts-list 3422 "queue" subqueue 3423queue-rule = "queue" string [ "on" interface-name ] queueopts-list 3424 subqueue 3425 3426anchor-rule = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ] 3427 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ] 3428 3429anchor-close = "}" 3430 3431trans-anchors = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string 3432 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ] 3433 3434load-anchor = "load anchor" string "from" filename 3435 3436queueopts-list = queueopts-list queueopts | queueopts 3437queueopts = [ "bandwidth" bandwidth-spec ] | 3438 [ "qlimit" number ] | [ "tbrsize" number ] | 3439 [ "priority" number ] | [ schedulers ] 3440schedulers = ( cbq-def | priq-def | hfsc-def ) 3441bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" ) 3442 3443etheraction = "pass" | "block" 3444action = "pass" | "match" | "block" [ return ] | [ "no" ] "scrub" 3445return = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] | 3446 "return-icmp" [ "(" icmpcode [ [ "," ] icmp6code ] ")" ] | 3447 "return-icmp6" [ "(" icmp6code ")" ] 3448icmpcode = ( icmp-code-name | icmp-code-number ) 3449icmp6code = ( icmp6-code-name | icmp6-code-number ) 3450 3451ifspec = ( [ "!" ] ( interface-name | interface-group ) ) | 3452 "{" interface-list "}" 3453interface-list = [ "!" ] ( interface-name | interface-group ) 3454 [ [ "," ] interface-list ] 3455route = ( "route-to" | "reply-to" | "dup-to" ) 3456 ( routehost | "{" routehost-list "}" ) 3457 [ pooltype ] 3458af = "inet" | "inet6" 3459 3460etherprotospec = "proto" ( proto-number | "{" etherproto-list "}" ) 3461etherproto-list = proto-number [ [ "," ] etherproto-list ] 3462protospec = "proto" ( proto-name | proto-number | 3463 "{" proto-list "}" ) 3464proto-list = ( proto-name | proto-number ) [ [ "," ] proto-list ] 3465 3466etherhosts = "from" macaddress "to" macaddress 3467macaddress = mac | mac "/" masklen | mac "&" mask 3468 3469hosts = "all" | 3470 "from" ( "any" | "no-route" | "urpf-failed" | "self" | host | 3471 "{" host-list "}" ) [ port ] [ os ] 3472 "to" ( "any" | "no-route" | "self" | host | 3473 "{" host-list "}" ) [ port ] 3474 3475ipspec = "any" | host | "{" host-list "}" 3476host = [ "!" ] ( address [ "/" mask-bits ] | "<" string ">" ) 3477redirhost = address [ "/" mask-bits ] 3478routehost = "(" interface-name [ address [ "/" mask-bits ] ] ")" 3479address = ( interface-name | interface-group | 3480 "(" ( interface-name | interface-group ) ")" | 3481 hostname | ipv4-dotted-quad | ipv6-coloned-hex ) 3482host-list = host [ [ "," ] host-list ] 3483redirhost-list = redirhost [ [ "," ] redirhost-list ] 3484routehost-list = routehost [ [ "," ] routehost-list ] 3485 3486port = "port" ( unary-op | binary-op | "{" op-list "}" ) 3487portspec = "port" ( number | name ) [ ":" ( "*" | number | name ) ] 3488os = "os" ( os-name | "{" os-list "}" ) 3489user = "user" ( unary-op | binary-op | "{" op-list "}" ) 3490group = "group" ( unary-op | binary-op | "{" op-list "}" ) 3491 3492unary-op = [ "=" | "!=" | "<" | "<=" | ">" | ">=" ] 3493 ( name | number ) 3494binary-op = number ( "<>" | "><" | ":" ) number 3495op-list = ( unary-op | binary-op ) [ [ "," ] op-list ] 3496 3497os-name = operating-system-name 3498os-list = os-name [ [ "," ] os-list ] 3499 3500flags = "flags" ( [ flag-set ] "/" flag-set | "any" ) 3501flag-set = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ] 3502 [ "W" ] 3503 3504icmp-type = "icmp-type" ( icmp-type-code | "{" icmp-list "}" ) 3505icmp6-type = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" ) 3506icmp-type-code = ( icmp-type-name | icmp-type-number ) 3507 [ "code" ( icmp-code-name | icmp-code-number ) ] 3508icmp-list = icmp-type-code [ [ "," ] icmp-list ] 3509 3510tos = ( "lowdelay" | "throughput" | "reliability" | 3511 [ "0x" ] number ) 3512 3513state-opts = state-opt [ [ "," ] state-opts ] 3514state-opt = ( "max" number | "no-sync" | timeout | "sloppy" | 3515 "source-track" [ ( "rule" | "global" ) ] | 3516 "max-src-nodes" number | "max-src-states" number | 3517 "max-src-conn" number | 3518 "max-src-conn-rate" number "/" number | 3519 "overload" "<" string ">" [ "flush" ] | 3520 "if-bound" | "floating" | "pflow" ) 3521 3522fragmentation = [ "fragment reassemble" ] 3523 3524timeout-list = timeout [ [ "," ] timeout-list ] 3525timeout = ( "tcp.first" | "tcp.opening" | "tcp.established" | 3526 "tcp.closing" | "tcp.finwait" | "tcp.closed" | 3527 "sctp.first" | "sctp.opening" | "sctp.established" | 3528 "sctp.closing" | "sctp.closed" | 3529 "udp.first" | "udp.single" | "udp.multiple" | 3530 "icmp.first" | "icmp.error" | 3531 "other.first" | "other.single" | "other.multiple" | 3532 "frag" | "interval" | "src.track" | 3533 "adaptive.start" | "adaptive.end" ) number 3534 3535limit-list = limit-item [ [ "," ] limit-list ] 3536limit-item = ( "states" | "frags" | "src-nodes" ) number 3537 3538pooltype = ( "bitmask" | "random" | 3539 "source-hash" [ ( hex-key | string-key ) ] | 3540 "round-robin" ) [ sticky-address ] 3541 3542subqueue = string | "{" queue-list "}" 3543queue-list = string [ [ "," ] string ] 3544cbq-def = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ] 3545priq-def = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ] 3546hfsc-def = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ] 3547cbq-opt = ( "default" | "borrow" | "red" | "ecn" | "rio" ) 3548priq-opt = ( "default" | "red" | "ecn" | "rio" ) 3549hfsc-opt = ( "default" | "red" | "ecn" | "rio" | 3550 linkshare-sc | realtime-sc | upperlimit-sc ) 3551linkshare-sc = "linkshare" sc-spec 3552realtime-sc = "realtime" sc-spec 3553upperlimit-sc = "upperlimit" sc-spec 3554sc-spec = ( bandwidth-spec | 3555 "(" bandwidth-spec number bandwidth-spec ")" ) 3556include = "include" filename 3557.Ed 3558.Sh FILES 3559.Bl -tag -width "/etc/protocols" -compact 3560.It Pa /etc/hosts 3561Host name database. 3562.It Pa /etc/pf.conf 3563Default location of the ruleset file. 3564The file has to be created manually as it is not installed with a 3565standard installation. 3566.It Pa /etc/pf.os 3567Default location of OS fingerprints. 3568.It Pa /etc/protocols 3569Protocol name database. 3570.It Pa /etc/services 3571Service name database. 3572.El 3573.Sh SEE ALSO 3574.Xr altq 4 , 3575.Xr carp 4 , 3576.Xr icmp 4 , 3577.Xr icmp6 4 , 3578.Xr ip 4 , 3579.Xr ip6 4 , 3580.Xr pf 4 , 3581.Xr pflow 4 , 3582.Xr pfsync 4 , 3583.Xr sctp 4 , 3584.Xr tcp 4 , 3585.Xr udp 4 , 3586.Xr hosts 5 , 3587.Xr pf.os 5 , 3588.Xr protocols 5 , 3589.Xr services 5 , 3590.Xr ftp-proxy 8 , 3591.Xr pfctl 8 , 3592.Xr pflogd 8 3593.Sh HISTORY 3594The 3595.Nm 3596file format first appeared in 3597.Ox 3.0 . 3598