1.\" $FreeBSD$ 2.\" $OpenBSD: pf.conf.5,v 1.406 2009/01/31 19:37:12 sobrado Exp $ 3.\" 4.\" Copyright (c) 2002, Daniel Hartmeier 5.\" All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" - Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" - Redistributions in binary form must reproduce the above 14.\" copyright notice, this list of conditions and the following 15.\" disclaimer in the documentation and/or other materials provided 16.\" with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 21.\" FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 22.\" COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 23.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 24.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 25.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 26.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 28.\" ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29.\" POSSIBILITY OF SUCH DAMAGE. 30.\" 31.Dd April 19, 2021 32.Dt PF.CONF 5 33.Os 34.Sh NAME 35.Nm pf.conf 36.Nd packet filter configuration file 37.Sh DESCRIPTION 38The 39.Xr pf 4 40packet filter modifies, drops or passes packets according to rules or 41definitions specified in 42.Nm pf.conf . 43.Sh STATEMENT ORDER 44There are seven types of statements in 45.Nm pf.conf : 46.Bl -tag -width xxxx 47.It Cm Macros 48User-defined variables may be defined and used later, simplifying 49the configuration file. 50Macros must be defined before they are referenced in 51.Nm pf.conf . 52.It Cm Tables 53Tables provide a mechanism for increasing the performance and flexibility of 54rules with large numbers of source or destination addresses. 55.It Cm Options 56Options tune the behaviour of the packet filtering engine. 57.It Cm Traffic Normalization Li (e.g. Em scrub ) 58Traffic normalization protects internal machines against inconsistencies 59in Internet protocols and implementations. 60.It Cm Queueing 61Queueing provides rule-based bandwidth control. 62.It Cm Translation Li (Various forms of NAT) 63Translation rules specify how addresses are to be mapped or redirected to 64other addresses. 65.It Cm Packet Filtering 66Packet filtering provides rule-based blocking or passing of packets. 67.El 68.Pp 69With the exception of 70.Cm macros 71and 72.Cm tables , 73the types of statements should be grouped and appear in 74.Nm pf.conf 75in the order shown above, as this matches the operation of the underlying 76packet filtering engine. 77By default 78.Xr pfctl 8 79enforces this order (see 80.Ar set require-order 81below). 82.Pp 83Comments can be put anywhere in the file using a hash mark 84.Pq Sq # , 85and extend to the end of the current line. 86.Pp 87Additional configuration files can be included with the 88.Ic include 89keyword, for example: 90.Bd -literal -offset indent 91include "/etc/pf/sub.filter.conf" 92.Ed 93.Sh MACROS 94Macros can be defined that will later be expanded in context. 95Macro names must start with a letter, and may contain letters, digits 96and underscores. 97Macro names may not be reserved words (for example 98.Ar pass , 99.Ar in , 100.Ar out ) . 101Macros are not expanded inside quotes. 102.Pp 103For example, 104.Bd -literal -offset indent 105ext_if = \&"kue0\&" 106all_ifs = \&"{\&" $ext_if lo0 \&"}\&" 107pass out on $ext_if from any to any 108pass in on $ext_if proto tcp from any to any port 25 109.Ed 110.Sh TABLES 111Tables are named structures which can hold a collection of addresses and 112networks. 113Lookups against tables in 114.Xr pf 4 115are relatively fast, making a single rule with tables much more efficient, 116in terms of 117processor usage and memory consumption, than a large number of rules which 118differ only in IP address (either created explicitly or automatically by rule 119expansion). 120.Pp 121Tables can be used as the source or destination of filter rules, 122.Ar scrub 123rules 124or 125translation rules such as 126.Ar nat 127or 128.Ar rdr 129(see below for details on the various rule types). 130Tables can also be used for the redirect address of 131.Ar nat 132and 133.Ar rdr 134rules and in the routing options of filter rules, but only for 135.Ar round-robin 136pools. 137.Pp 138Tables can be defined with any of the following 139.Xr pfctl 8 140mechanisms. 141As with macros, reserved words may not be used as table names. 142.Bl -tag -width "manually" 143.It Ar manually 144Persistent tables can be manually created with the 145.Ar add 146or 147.Ar replace 148option of 149.Xr pfctl 8 , 150before or after the ruleset has been loaded. 151.It Pa pf.conf 152Table definitions can be placed directly in this file, and loaded at the 153same time as other rules are loaded, atomically. 154Table definitions inside 155.Nm pf.conf 156use the 157.Ar table 158statement, and are especially useful to define non-persistent tables. 159The contents of a pre-existing table defined without a list of addresses 160to initialize it is not altered when 161.Nm pf.conf 162is loaded. 163A table initialized with the empty list, 164.Li { } , 165will be cleared on load. 166.El 167.Pp 168Tables may be defined with the following attributes: 169.Bl -tag -width persist 170.It Ar persist 171The 172.Ar persist 173flag forces the kernel to keep the table even when no rules refer to it. 174If the flag is not set, the kernel will automatically remove the table 175when the last rule referring to it is flushed. 176.It Ar const 177The 178.Ar const 179flag prevents the user from altering the contents of the table once it 180has been created. 181Without that flag, 182.Xr pfctl 8 183can be used to add or remove addresses from the table at any time, even 184when running with 185.Xr securelevel 7 186= 2. 187.It Ar counters 188The 189.Ar counters 190flag enables per-address packet and byte counters which can be displayed with 191.Xr pfctl 8 . 192Note that this feature carries significant memory overhead for large tables. 193.El 194.Pp 195For example, 196.Bd -literal -offset indent 197table \*(Ltprivate\*(Gt const { 10/8, 172.16/12, 192.168/16 } 198table \*(Ltbadhosts\*(Gt persist 199block on fxp0 from { \*(Ltprivate\*(Gt, \*(Ltbadhosts\*(Gt } to any 200.Ed 201.Pp 202creates a table called private, to hold RFC 1918 private network 203blocks, and a table called badhosts, which is initially empty. 204A filter rule is set up to block all traffic coming from addresses listed in 205either table. 206The private table cannot have its contents changed and the badhosts table 207will exist even when no active filter rules reference it. 208Addresses may later be added to the badhosts table, so that traffic from 209these hosts can be blocked by using 210.Bd -literal -offset indent 211# pfctl -t badhosts -Tadd 204.92.77.111 212.Ed 213.Pp 214A table can also be initialized with an address list specified in one or more 215external files, using the following syntax: 216.Bd -literal -offset indent 217table \*(Ltspam\*(Gt persist file \&"/etc/spammers\&" file \&"/etc/openrelays\&" 218block on fxp0 from \*(Ltspam\*(Gt to any 219.Ed 220.Pp 221The files 222.Pa /etc/spammers 223and 224.Pa /etc/openrelays 225list IP addresses, one per line. 226Any lines beginning with a # are treated as comments and ignored. 227In addition to being specified by IP address, hosts may also be 228specified by their hostname. 229When the resolver is called to add a hostname to a table, 230.Em all 231resulting IPv4 and IPv6 addresses are placed into the table. 232IP addresses can also be entered in a table by specifying a valid interface 233name, a valid interface group or the 234.Em self 235keyword, in which case all addresses assigned to the interface(s) will be 236added to the table. 237.Sh OPTIONS 238.Xr pf 4 239may be tuned for various situations using the 240.Ar set 241command. 242.Bl -tag -width xxxx 243.It Ar set timeout 244.Pp 245.Bl -tag -width "src.track" -compact 246.It Ar interval 247Interval between purging expired states and fragments. 248.It Ar frag 249Seconds before an unassembled fragment is expired. 250.It Ar src.track 251Length of time to retain a source tracking entry after the last state 252expires. 253.El 254.Pp 255When a packet matches a stateful connection, the seconds to live for the 256connection will be updated to that of the 257.Ar proto.modifier 258which corresponds to the connection state. 259Each packet which matches this state will reset the TTL. 260Tuning these values may improve the performance of the 261firewall at the risk of dropping valid idle connections. 262.Pp 263.Bl -tag -width xxxx -compact 264.It Ar tcp.first 265The state after the first packet. 266.It Ar tcp.opening 267The state before the destination host ever sends a packet. 268.It Ar tcp.established 269The fully established state. 270.It Ar tcp.closing 271The state after the first FIN has been sent. 272.It Ar tcp.finwait 273The state after both FINs have been exchanged and the connection is closed. 274Some hosts (notably web servers on Solaris) send TCP packets even after closing 275the connection. 276Increasing 277.Ar tcp.finwait 278(and possibly 279.Ar tcp.closing ) 280can prevent blocking of such packets. 281.It Ar tcp.closed 282The state after one endpoint sends an RST. 283.El 284.Pp 285ICMP and UDP are handled in a fashion similar to TCP, but with a much more 286limited set of states: 287.Pp 288.Bl -tag -width xxxx -compact 289.It Ar udp.first 290The state after the first packet. 291.It Ar udp.single 292The state if the source host sends more than one packet but the destination 293host has never sent one back. 294.It Ar udp.multiple 295The state if both hosts have sent packets. 296.It Ar icmp.first 297The state after the first packet. 298.It Ar icmp.error 299The state after an ICMP error came back in response to an ICMP packet. 300.El 301.Pp 302Other protocols are handled similarly to UDP: 303.Pp 304.Bl -tag -width xxxx -compact 305.It Ar other.first 306.It Ar other.single 307.It Ar other.multiple 308.El 309.Pp 310Timeout values can be reduced adaptively as the number of state table 311entries grows. 312.Pp 313.Bl -tag -width xxxx -compact 314.It Ar adaptive.start 315When the number of state entries exceeds this value, adaptive scaling 316begins. 317All timeout values are scaled linearly with factor 318(adaptive.end - number of states) / (adaptive.end - adaptive.start). 319.It Ar adaptive.end 320When reaching this number of state entries, all timeout values become 321zero, effectively purging all state entries immediately. 322This value is used to define the scale factor, it should not actually 323be reached (set a lower state limit, see below). 324.El 325.Pp 326Adaptive timeouts are enabled by default, with an adaptive.start value 327equal to 60% of the state limit, and an adaptive.end value equal to 328120% of the state limit. 329They can be disabled by setting both adaptive.start and adaptive.end to 0. 330.Pp 331The adaptive timeout values can be defined both globally and for each rule. 332When used on a per-rule basis, the values relate to the number of 333states created by the rule, otherwise to the total number of 334states. 335.Pp 336For example: 337.Bd -literal -offset indent 338set timeout tcp.first 120 339set timeout tcp.established 86400 340set timeout { adaptive.start 6000, adaptive.end 12000 } 341set limit states 10000 342.Ed 343.Pp 344With 9000 state table entries, the timeout values are scaled to 50% 345(tcp.first 60, tcp.established 43200). 346.It Ar set loginterface 347Enable collection of packet and byte count statistics for the given 348interface or interface group. 349These statistics can be viewed using 350.Bd -literal -offset indent 351# pfctl -s info 352.Ed 353.Pp 354In this example 355.Xr pf 4 356collects statistics on the interface named dc0: 357.Bd -literal -offset indent 358set loginterface dc0 359.Ed 360.Pp 361One can disable the loginterface using: 362.Bd -literal -offset indent 363set loginterface none 364.Ed 365.It Ar set limit 366Sets hard limits on the memory pools used by the packet filter. 367See 368.Xr zone 9 369for an explanation of memory pools. 370.Pp 371For example, 372.Bd -literal -offset indent 373set limit states 20000 374.Ed 375.Pp 376sets the maximum number of entries in the memory pool used by state table 377entries (generated by 378.Ar pass 379rules which do not specify 380.Ar no state ) 381to 20000. 382Using 383.Bd -literal -offset indent 384set limit frags 20000 385.Ed 386.Pp 387sets the maximum number of entries in the memory pool used for fragment 388reassembly (generated by 389.Ar scrub 390rules) to 20000. 391Using 392.Bd -literal -offset indent 393set limit src-nodes 2000 394.Ed 395.Pp 396sets the maximum number of entries in the memory pool used for tracking 397source IP addresses (generated by the 398.Ar sticky-address 399and 400.Ar src.track 401options) to 2000. 402Using 403.Bd -literal -offset indent 404set limit tables 1000 405set limit table-entries 100000 406.Ed 407.Pp 408sets limits on the memory pools used by tables. 409The first limits the number of tables that can exist to 1000. 410The second limits the overall number of addresses that can be stored 411in tables to 100000. 412.Pp 413Various limits can be combined on a single line: 414.Bd -literal -offset indent 415set limit { states 20000, frags 20000, src-nodes 2000 } 416.Ed 417.It Ar set ruleset-optimization 418.Bl -tag -width xxxxxxxx -compact 419.It Ar none 420Disable the ruleset optimizer. 421.It Ar basic 422Enable basic ruleset optimization. 423This is the default behaviour. 424Basic ruleset optimization does four things to improve the 425performance of ruleset evaluations: 426.Pp 427.Bl -enum -compact 428.It 429remove duplicate rules 430.It 431remove rules that are a subset of another rule 432.It 433combine multiple rules into a table when advantageous 434.It 435re-order the rules to improve evaluation performance 436.El 437.Pp 438.It Ar profile 439Uses the currently loaded ruleset as a feedback profile to tailor the 440ordering of quick rules to actual network traffic. 441.El 442.Pp 443It is important to note that the ruleset optimizer will modify the ruleset 444to improve performance. 445A side effect of the ruleset modification is that per-rule accounting 446statistics will have different meanings than before. 447If per-rule accounting is important for billing purposes or whatnot, 448either the ruleset optimizer should not be used or a label field should 449be added to all of the accounting rules to act as optimization barriers. 450.Pp 451Optimization can also be set as a command-line argument to 452.Xr pfctl 8 , 453overriding the settings in 454.Nm . 455.It Ar set optimization 456Optimize state timeouts for one of the following network environments: 457.Pp 458.Bl -tag -width xxxx -compact 459.It Ar normal 460A normal network environment. 461Suitable for almost all networks. 462.It Ar high-latency 463A high-latency environment (such as a satellite connection). 464.It Ar satellite 465Alias for 466.Ar high-latency . 467.It Ar aggressive 468Aggressively expire connections. 469This can greatly reduce the memory usage of the firewall at the cost of 470dropping idle connections early. 471.It Ar conservative 472Extremely conservative settings. 473Avoid dropping legitimate connections at the 474expense of greater memory utilization (possibly much greater on a busy 475network) and slightly increased processor utilization. 476.El 477.Pp 478For example: 479.Bd -literal -offset indent 480set optimization aggressive 481.Ed 482.It Ar set block-policy 483The 484.Ar block-policy 485option sets the default behaviour for the packet 486.Ar block 487action: 488.Pp 489.Bl -tag -width xxxxxxxx -compact 490.It Ar drop 491Packet is silently dropped. 492.It Ar return 493A TCP RST is returned for blocked TCP packets, 494an ICMP UNREACHABLE is returned for blocked UDP packets, 495and all other packets are silently dropped. 496.El 497.Pp 498For example: 499.Bd -literal -offset indent 500set block-policy return 501.Ed 502.It Ar set fail-policy 503The 504.Ar fail-policy 505option sets the behaviour of rules which should pass a packet but were 506unable to do so. 507This might happen when a nat or route-to rule uses an empty table as list 508of targets or if a rule fails to create state or source node. 509The following 510.Ar block 511actions are possible: 512.Pp 513.Bl -tag -width xxxxxxxx -compact 514.It Ar drop 515Incoming packet is silently dropped. 516.It Ar return 517Incoming packet is dropped and TCP RST is returned for TCP packets, 518an ICMP UNREACHABLE is returned for UDP packets, 519and no response is sent for other packets. 520.El 521.Pp 522For example: 523.Bd -literal -offset indent 524set fail-policy return 525.Ed 526.It Ar set state-policy 527The 528.Ar state-policy 529option sets the default behaviour for states: 530.Pp 531.Bl -tag -width group-bound -compact 532.It Ar if-bound 533States are bound to interface. 534.It Ar floating 535States can match packets on any interfaces (the default). 536.El 537.Pp 538For example: 539.Bd -literal -offset indent 540set state-policy if-bound 541.Ed 542.It Ar set state-defaults 543The 544.Ar state-defaults 545option sets the state options for states created from rules 546without an explicit 547.Ar keep state . 548For example: 549.Bd -literal -offset indent 550set state-defaults no-sync 551.Ed 552.It Ar set hostid 553The 32-bit 554.Ar hostid 555identifies this firewall's state table entries to other firewalls 556in a 557.Xr pfsync 4 558failover cluster. 559By default the hostid is set to a pseudo-random value, however it may be 560desirable to manually configure it, for example to more easily identify the 561source of state table entries. 562.Bd -literal -offset indent 563set hostid 1 564.Ed 565.Pp 566The hostid may be specified in either decimal or hexadecimal. 567.It Ar set require-order 568By default 569.Xr pfctl 8 570enforces an ordering of the statement types in the ruleset to: 571.Em options , 572.Em normalization , 573.Em queueing , 574.Em translation , 575.Em filtering . 576Setting this option to 577.Ar no 578disables this enforcement. 579There may be non-trivial and non-obvious implications to an out of 580order ruleset. 581Consider carefully before disabling the order enforcement. 582.It Ar set fingerprints 583Load fingerprints of known operating systems from the given filename. 584By default fingerprints of known operating systems are automatically 585loaded from 586.Xr pf.os 5 587in 588.Pa /etc 589but can be overridden via this option. 590Setting this option may leave a small period of time where the fingerprints 591referenced by the currently active ruleset are inconsistent until the new 592ruleset finishes loading. 593.Pp 594For example: 595.Pp 596.Dl set fingerprints \&"/etc/pf.os.devel\&" 597.It Ar set skip on Aq Ar ifspec 598List interfaces for which packets should not be filtered. 599Packets passing in or out on such interfaces are passed as if pf was 600disabled, i.e. pf does not process them in any way. 601This can be useful on loopback and other virtual interfaces, when 602packet filtering is not desired and can have unexpected effects. 603For example: 604.Pp 605.Dl set skip on lo0 606.It Ar set debug 607Set the debug 608.Ar level 609to one of the following: 610.Pp 611.Bl -tag -width xxxxxxxxxxxx -compact 612.It Ar none 613Don't generate debug messages. 614.It Ar urgent 615Generate debug messages only for serious errors. 616.It Ar misc 617Generate debug messages for various errors. 618.It Ar loud 619Generate debug messages for common conditions. 620.El 621.It Ar set keepcounters 622Preserve rule counters across rule updates. 623Usually rule counters are reset to zero on every update of the ruleset. 624With 625.Ar keepcounters 626set pf will attempt to find matching rules between old and new rulesets 627and preserve the rule counters. 628.El 629.Sh TRAFFIC NORMALIZATION 630Traffic normalization is used to sanitize packet content in such 631a way that there are no ambiguities in packet interpretation on 632the receiving side. 633The normalizer does IP fragment reassembly to prevent attacks 634that confuse intrusion detection systems by sending overlapping 635IP fragments. 636Packet normalization is invoked with the 637.Ar scrub 638directive. 639.Pp 640.Ar scrub 641has the following options: 642.Bl -tag -width xxxx 643.It Ar no-df 644Clears the 645.Ar dont-fragment 646bit from a matching IP packet. 647Some operating systems are known to generate fragmented packets with the 648.Ar dont-fragment 649bit set. 650This is particularly true with NFS. 651.Ar Scrub 652will drop such fragmented 653.Ar dont-fragment 654packets unless 655.Ar no-df 656is specified. 657.Pp 658Unfortunately some operating systems also generate their 659.Ar dont-fragment 660packets with a zero IP identification field. 661Clearing the 662.Ar dont-fragment 663bit on packets with a zero IP ID may cause deleterious results if an 664upstream router later fragments the packet. 665Using the 666.Ar random-id 667modifier (see below) is recommended in combination with the 668.Ar no-df 669modifier to ensure unique IP identifiers. 670.It Ar min-ttl Aq Ar number 671Enforces a minimum TTL for matching IP packets. 672.It Ar max-mss Aq Ar number 673Enforces a maximum MSS for matching TCP packets. 674.It Xo Ar set-tos Aq Ar string 675.No \*(Ba Aq Ar number 676.Xc 677Enforces a 678.Em TOS 679for matching IP packets. 680.Em TOS 681may be 682given as one of 683.Ar critical , 684.Ar inetcontrol , 685.Ar lowdelay , 686.Ar netcontrol , 687.Ar throughput , 688.Ar reliability , 689or one of the DiffServ Code Points: 690.Ar ef , 691.Ar va , 692.Ar af11 No ... Ar af43 , 693.Ar cs0 No ... Ar cs7 ; 694or as either hex or decimal. 695.It Ar random-id 696Replaces the IP identification field with random values to compensate 697for predictable values generated by many hosts. 698This option only applies to packets that are not fragmented 699after the optional fragment reassembly. 700.It Ar fragment reassemble 701Using 702.Ar scrub 703rules, fragments can be reassembled by normalization. 704In this case, fragments are buffered until they form a complete 705packet, and only the completed packet is passed on to the filter. 706The advantage is that filter rules have to deal only with complete 707packets, and can ignore fragments. 708The drawback of caching fragments is the additional memory cost. 709.It Ar reassemble tcp 710Statefully normalizes TCP connections. 711.Ar scrub reassemble tcp 712rules may not have the direction (in/out) specified. 713.Ar reassemble tcp 714performs the following normalizations: 715.Pp 716.Bl -tag -width timeout -compact 717.It ttl 718Neither side of the connection is allowed to reduce their IP TTL. 719An attacker may send a packet such that it reaches the firewall, affects 720the firewall state, and expires before reaching the destination host. 721.Ar reassemble tcp 722will raise the TTL of all packets back up to the highest value seen on 723the connection. 724.It timestamp modulation 725Modern TCP stacks will send a timestamp on every TCP packet and echo 726the other endpoint's timestamp back to them. 727Many operating systems will merely start the timestamp at zero when 728first booted, and increment it several times a second. 729The uptime of the host can be deduced by reading the timestamp and multiplying 730by a constant. 731Also observing several different timestamps can be used to count hosts 732behind a NAT device. 733And spoofing TCP packets into a connection requires knowing or guessing 734valid timestamps. 735Timestamps merely need to be monotonically increasing and not derived off a 736guessable base time. 737.Ar reassemble tcp 738will cause 739.Ar scrub 740to modulate the TCP timestamps with a random number. 741.It extended PAWS checks 742There is a problem with TCP on long fat pipes, in that a packet might get 743delayed for longer than it takes the connection to wrap its 32-bit sequence 744space. 745In such an occurrence, the old packet would be indistinguishable from a 746new packet and would be accepted as such. 747The solution to this is called PAWS: Protection Against Wrapped Sequence 748numbers. 749It protects against it by making sure the timestamp on each packet does 750not go backwards. 751.Ar reassemble tcp 752also makes sure the timestamp on the packet does not go forward more 753than the RFC allows. 754By doing this, 755.Xr pf 4 756artificially extends the security of TCP sequence numbers by 10 to 18 757bits when the host uses appropriately randomized timestamps, since a 758blind attacker would have to guess the timestamp as well. 759.El 760.El 761.Pp 762For example, 763.Bd -literal -offset indent 764scrub in on $ext_if all fragment reassemble 765.Ed 766.Pp 767The 768.Ar no 769option prefixed to a scrub rule causes matching packets to remain unscrubbed, 770much in the same way as 771.Ar drop quick 772works in the packet filter (see below). 773This mechanism should be used when it is necessary to exclude specific packets 774from broader scrub rules. 775.Sh QUEUEING 776The ALTQ system is currently not available in the GENERIC kernel nor as 777loadable modules. 778In order to use the herein after called queueing options one has to use a 779custom built kernel. 780Please refer to 781.Xr altq 4 782to learn about the related kernel options. 783.Pp 784Packets can be assigned to queues for the purpose of bandwidth 785control. 786At least two declarations are required to configure queues, and later 787any packet filtering rule can reference the defined queues by name. 788During the filtering component of 789.Nm pf.conf , 790the last referenced 791.Ar queue 792name is where any packets from 793.Ar pass 794rules will be queued, while for 795.Ar block 796rules it specifies where any resulting ICMP or TCP RST 797packets should be queued. 798The 799.Ar scheduler 800defines the algorithm used to decide which packets get delayed, dropped, or 801sent out immediately. 802There are three 803.Ar schedulers 804currently supported. 805.Bl -tag -width xxxx 806.It Ar cbq 807Class Based Queueing. 808.Ar Queues 809attached to an interface build a tree, thus each 810.Ar queue 811can have further child 812.Ar queues . 813Each queue can have a 814.Ar priority 815and a 816.Ar bandwidth 817assigned. 818.Ar Priority 819mainly controls the time packets take to get sent out, while 820.Ar bandwidth 821has primarily effects on throughput. 822.Ar cbq 823achieves both partitioning and sharing of link bandwidth 824by hierarchically structured classes. 825Each class has its own 826.Ar queue 827and is assigned its share of 828.Ar bandwidth . 829A child class can borrow bandwidth from its parent class 830as long as excess bandwidth is available 831(see the option 832.Ar borrow , 833below). 834.It Ar priq 835Priority Queueing. 836.Ar Queues 837are flat attached to the interface, thus, 838.Ar queues 839cannot have further child 840.Ar queues . 841Each 842.Ar queue 843has a unique 844.Ar priority 845assigned, ranging from 0 to 15. 846Packets in the 847.Ar queue 848with the highest 849.Ar priority 850are processed first. 851.It Ar hfsc 852Hierarchical Fair Service Curve. 853.Ar Queues 854attached to an interface build a tree, thus each 855.Ar queue 856can have further child 857.Ar queues . 858Each queue can have a 859.Ar priority 860and a 861.Ar bandwidth 862assigned. 863.Ar Priority 864mainly controls the time packets take to get sent out, while 865.Ar bandwidth 866primarily affects throughput. 867.Ar hfsc 868supports both link-sharing and guaranteed real-time services. 869It employs a service curve based QoS model, 870and its unique feature is an ability to decouple 871.Ar delay 872and 873.Ar bandwidth 874allocation. 875.El 876.Pp 877The interfaces on which queueing should be activated are declared using 878the 879.Ar altq on 880declaration. 881.Ar altq on 882has the following keywords: 883.Bl -tag -width xxxx 884.It Aq Ar interface 885Queueing is enabled on the named interface. 886.It Aq Ar scheduler 887Specifies which queueing scheduler to use. 888Currently supported values 889are 890.Ar cbq 891for Class Based Queueing, 892.Ar priq 893for Priority Queueing and 894.Ar hfsc 895for the Hierarchical Fair Service Curve scheduler. 896.It Ar bandwidth Aq Ar bw 897The maximum bitrate for all queues on an 898interface may be specified using the 899.Ar bandwidth 900keyword. 901The value can be specified as an absolute value or as a 902percentage of the interface bandwidth. 903When using an absolute value, the suffixes 904.Ar b , 905.Ar Kb , 906.Ar Mb , 907and 908.Ar Gb 909are used to represent bits, kilobits, megabits, and 910gigabits per second, respectively. 911The value must not exceed the interface bandwidth. 912If 913.Ar bandwidth 914is not specified, the interface bandwidth is used 915(but take note that some interfaces do not know their bandwidth, 916or can adapt their bandwidth rates). 917.It Ar qlimit Aq Ar limit 918The maximum number of packets held in the queue. 919The default is 50. 920.It Ar tbrsize Aq Ar size 921Adjusts the size, in bytes, of the token bucket regulator. 922If not specified, heuristics based on the 923interface bandwidth are used to determine the size. 924.It Ar queue Aq Ar list 925Defines a list of subqueues to create on an interface. 926.El 927.Pp 928In the following example, the interface dc0 929should queue up to 5Mbps in four second-level queues using 930Class Based Queueing. 931Those four queues will be shown in a later example. 932.Bd -literal -offset indent 933altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh } 934.Ed 935.Pp 936Once interfaces are activated for queueing using the 937.Ar altq 938directive, a sequence of 939.Ar queue 940directives may be defined. 941The name associated with a 942.Ar queue 943must match a queue defined in the 944.Ar altq 945directive (e.g. mail), or, except for the 946.Ar priq 947.Ar scheduler , 948in a parent 949.Ar queue 950declaration. 951The following keywords can be used: 952.Bl -tag -width xxxx 953.It Ar on Aq Ar interface 954Specifies the interface the queue operates on. 955If not given, it operates on all matching interfaces. 956.It Ar bandwidth Aq Ar bw 957Specifies the maximum bitrate to be processed by the queue. 958This value must not exceed the value of the parent 959.Ar queue 960and can be specified as an absolute value or a percentage of the parent 961queue's bandwidth. 962If not specified, defaults to 100% of the parent queue's bandwidth. 963The 964.Ar priq 965scheduler does not support bandwidth specification. 966.It Ar priority Aq Ar level 967Between queues a priority level can be set. 968For 969.Ar cbq 970and 971.Ar hfsc , 972the range is 0 to 7 and for 973.Ar priq , 974the range is 0 to 15. 975The default for all is 1. 976.Ar Priq 977queues with a higher priority are always served first. 978.Ar Cbq 979and 980.Ar Hfsc 981queues with a higher priority are preferred in the case of overload. 982.It Ar qlimit Aq Ar limit 983The maximum number of packets held in the queue. 984The default is 50. 985.El 986.Pp 987The 988.Ar scheduler 989can get additional parameters with 990.Xo Aq Ar scheduler 991.Pf ( Aq Ar parameters ) . 992.Xc 993Parameters are as follows: 994.Bl -tag -width Fl 995.It Ar default 996Packets not matched by another queue are assigned to this one. 997Exactly one default queue is required. 998.It Ar red 999Enable RED (Random Early Detection) on this queue. 1000RED drops packets with a probability proportional to the average 1001queue length. 1002.It Ar rio 1003Enables RIO on this queue. 1004RIO is RED with IN/OUT, thus running 1005RED two times more than RIO would achieve the same effect. 1006RIO is currently not supported in the GENERIC kernel. 1007.It Ar ecn 1008Enables ECN (Explicit Congestion Notification) on this queue. 1009ECN implies RED. 1010.El 1011.Pp 1012The 1013.Ar cbq 1014.Ar scheduler 1015supports an additional option: 1016.Bl -tag -width Fl 1017.It Ar borrow 1018The queue can borrow bandwidth from the parent. 1019.El 1020.Pp 1021The 1022.Ar hfsc 1023.Ar scheduler 1024supports some additional options: 1025.Bl -tag -width Fl 1026.It Ar realtime Aq Ar sc 1027The minimum required bandwidth for the queue. 1028.It Ar upperlimit Aq Ar sc 1029The maximum allowed bandwidth for the queue. 1030.It Ar linkshare Aq Ar sc 1031The bandwidth share of a backlogged queue. 1032.El 1033.Pp 1034.Aq Ar sc 1035is an acronym for 1036.Ar service curve . 1037.Pp 1038The format for service curve specifications is 1039.Ar ( m1 , d , m2 ) . 1040.Ar m2 1041controls the bandwidth assigned to the queue. 1042.Ar m1 1043and 1044.Ar d 1045are optional and can be used to control the initial bandwidth assignment. 1046For the first 1047.Ar d 1048milliseconds the queue gets the bandwidth given as 1049.Ar m1 , 1050afterwards the value given in 1051.Ar m2 . 1052.Pp 1053Furthermore, with 1054.Ar cbq 1055and 1056.Ar hfsc , 1057child queues can be specified as in an 1058.Ar altq 1059declaration, thus building a tree of queues using a part of 1060their parent's bandwidth. 1061.Pp 1062Packets can be assigned to queues based on filter rules by using the 1063.Ar queue 1064keyword. 1065Normally only one 1066.Ar queue 1067is specified; when a second one is specified it will instead be used for 1068packets which have a 1069.Em TOS 1070of 1071.Em lowdelay 1072and for TCP ACKs with no data payload. 1073.Pp 1074To continue the previous example, the examples below would specify the 1075four referenced 1076queues, plus a few child queues. 1077Interactive 1078.Xr ssh 1 1079sessions get priority over bulk transfers like 1080.Xr scp 1 1081and 1082.Xr sftp 1 . 1083The queues may then be referenced by filtering rules (see 1084.Sx PACKET FILTERING 1085below). 1086.Bd -literal 1087queue std bandwidth 10% cbq(default) 1088queue http bandwidth 60% priority 2 cbq(borrow red) \e 1089 { employees, developers } 1090queue developers bandwidth 75% cbq(borrow) 1091queue employees bandwidth 15% 1092queue mail bandwidth 10% priority 0 cbq(borrow ecn) 1093queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk } 1094queue ssh_interactive bandwidth 50% priority 7 cbq(borrow) 1095queue ssh_bulk bandwidth 50% priority 0 cbq(borrow) 1096 1097block return out on dc0 inet all queue std 1098pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e 1099 queue developers 1100pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e 1101 queue employees 1102pass out on dc0 inet proto tcp from any to any port 22 \e 1103 queue(ssh_bulk, ssh_interactive) 1104pass out on dc0 inet proto tcp from any to any port 25 \e 1105 queue mail 1106.Ed 1107.Sh TRANSLATION 1108Translation rules modify either the source or destination address of the 1109packets associated with a stateful connection. 1110A stateful connection is automatically created to track packets matching 1111such a rule as long as they are not blocked by the filtering section of 1112.Nm pf.conf . 1113The translation engine modifies the specified address and/or port in the 1114packet, recalculates IP, TCP and UDP checksums as necessary, and passes it to 1115the packet filter for evaluation. 1116.Pp 1117Since translation occurs before filtering the filter 1118engine will see packets as they look after any 1119addresses and ports have been translated. 1120Filter rules will therefore have to filter based on the translated 1121address and port number. 1122Packets that match a translation rule are only automatically passed if 1123the 1124.Ar pass 1125modifier is given, otherwise they are 1126still subject to 1127.Ar block 1128and 1129.Ar pass 1130rules. 1131.Pp 1132The state entry created permits 1133.Xr pf 4 1134to keep track of the original address for traffic associated with that state 1135and correctly direct return traffic for that connection. 1136.Pp 1137Various types of translation are possible with pf: 1138.Bl -tag -width xxxx 1139.It Ar binat 1140A 1141.Ar binat 1142rule specifies a bidirectional mapping between an external IP netblock 1143and an internal IP netblock. 1144.It Ar nat 1145A 1146.Ar nat 1147rule specifies that IP addresses are to be changed as the packet 1148traverses the given interface. 1149This technique allows one or more IP addresses 1150on the translating host to support network traffic for a larger range of 1151machines on an "inside" network. 1152Although in theory any IP address can be used on the inside, it is strongly 1153recommended that one of the address ranges defined by RFC 1918 be used. 1154These netblocks are: 1155.Bd -literal 115610.0.0.0 - 10.255.255.255 (all of net 10, i.e., 10/8) 1157172.16.0.0 - 172.31.255.255 (i.e., 172.16/12) 1158192.168.0.0 - 192.168.255.255 (i.e., 192.168/16) 1159.Ed 1160.It Pa rdr 1161The packet is redirected to another destination and possibly a 1162different port. 1163.Ar rdr 1164rules can optionally specify port ranges instead of single ports. 1165rdr ... port 2000:2999 -\*(Gt ... port 4000 1166redirects ports 2000 to 2999 (inclusive) to port 4000. 1167rdr ... port 2000:2999 -\*(Gt ... port 4000:* 1168redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999. 1169.El 1170.Pp 1171In addition to modifying the address, some translation rules may modify 1172source or destination ports for 1173.Xr tcp 4 1174or 1175.Xr udp 4 1176connections; implicitly in the case of 1177.Ar nat 1178rules and explicitly in the case of 1179.Ar rdr 1180rules. 1181Port numbers are never translated with a 1182.Ar binat 1183rule. 1184.Pp 1185Evaluation order of the translation rules is dependent on the type 1186of the translation rules and of the direction of a packet. 1187.Ar binat 1188rules are always evaluated first. 1189Then either the 1190.Ar rdr 1191rules are evaluated on an inbound packet or the 1192.Ar nat 1193rules on an outbound packet. 1194Rules of the same type are evaluated in the same order in which they 1195appear in the ruleset. 1196The first matching rule decides what action is taken. 1197.Pp 1198The 1199.Ar no 1200option prefixed to a translation rule causes packets to remain untranslated, 1201much in the same way as 1202.Ar drop quick 1203works in the packet filter (see below). 1204If no rule matches the packet it is passed to the filter engine unmodified. 1205.Pp 1206Translation rules apply only to packets that pass through 1207the specified interface, and if no interface is specified, 1208translation is applied to packets on all interfaces. 1209For instance, redirecting port 80 on an external interface to an internal 1210web server will only work for connections originating from the outside. 1211Connections to the address of the external interface from local hosts will 1212not be redirected, since such packets do not actually pass through the 1213external interface. 1214Redirections cannot reflect packets back through the interface they arrive 1215on, they can only be redirected to hosts connected to different interfaces 1216or to the firewall itself. 1217.Pp 1218Note that redirecting external incoming connections to the loopback 1219address, as in 1220.Bd -literal -offset indent 1221rdr on ne3 inet proto tcp to port smtp -\*(Gt 127.0.0.1 port spamd 1222.Ed 1223.Pp 1224will effectively allow an external host to connect to daemons 1225bound solely to the loopback address, circumventing the traditional 1226blocking of such connections on a real interface. 1227Unless this effect is desired, any of the local non-loopback addresses 1228should be used as redirection target instead, which allows external 1229connections only to daemons bound to this address or not bound to 1230any address. 1231.Pp 1232See 1233.Sx TRANSLATION EXAMPLES 1234below. 1235.Sh PACKET FILTERING 1236.Xr pf 4 1237has the ability to 1238.Ar block 1239and 1240.Ar pass 1241packets based on attributes of their layer 3 (see 1242.Xr ip 4 1243and 1244.Xr ip6 4 ) 1245and layer 4 (see 1246.Xr icmp 4 , 1247.Xr icmp6 4 , 1248.Xr tcp 4 , 1249.Xr udp 4 ) 1250headers. 1251In addition, packets may also be 1252assigned to queues for the purpose of bandwidth control. 1253.Pp 1254For each packet processed by the packet filter, the filter rules are 1255evaluated in sequential order, from first to last. 1256The last matching rule decides what action is taken. 1257If no rule matches the packet, the default action is to pass 1258the packet. 1259.Pp 1260The following actions can be used in the filter: 1261.Bl -tag -width xxxx 1262.It Ar block 1263The packet is blocked. 1264There are a number of ways in which a 1265.Ar block 1266rule can behave when blocking a packet. 1267The default behaviour is to 1268.Ar drop 1269packets silently, however this can be overridden or made 1270explicit either globally, by setting the 1271.Ar block-policy 1272option, or on a per-rule basis with one of the following options: 1273.Pp 1274.Bl -tag -width xxxx -compact 1275.It Ar drop 1276The packet is silently dropped. 1277.It Ar return-rst 1278This applies only to 1279.Xr tcp 4 1280packets, and issues a TCP RST which closes the 1281connection. 1282.It Ar return-icmp 1283.It Ar return-icmp6 1284This causes ICMP messages to be returned for packets which match the rule. 1285By default this is an ICMP UNREACHABLE message, however this 1286can be overridden by specifying a message as a code or number. 1287.It Ar return 1288This causes a TCP RST to be returned for 1289.Xr tcp 4 1290packets and an ICMP UNREACHABLE for UDP and other packets. 1291.El 1292.Pp 1293Options returning ICMP packets currently have no effect if 1294.Xr pf 4 1295operates on a 1296.Xr if_bridge 4 , 1297as the code to support this feature has not yet been implemented. 1298.Pp 1299The simplest mechanism to block everything by default and only pass 1300packets that match explicit rules is specify a first filter rule of: 1301.Bd -literal -offset indent 1302block all 1303.Ed 1304.It Ar pass 1305The packet is passed; 1306state is created unless the 1307.Ar no state 1308option is specified. 1309.El 1310.Pp 1311By default 1312.Xr pf 4 1313filters packets statefully; the first time a packet matches a 1314.Ar pass 1315rule, a state entry is created; for subsequent packets the filter checks 1316whether the packet matches any state. 1317If it does, the packet is passed without evaluation of any rules. 1318After the connection is closed or times out, the state entry is automatically 1319removed. 1320.Pp 1321This has several advantages. 1322For TCP connections, comparing a packet to a state involves checking 1323its sequence numbers, as well as TCP timestamps if a 1324.Ar scrub reassemble tcp 1325rule applies to the connection. 1326If these values are outside the narrow windows of expected 1327values, the packet is dropped. 1328This prevents spoofing attacks, such as when an attacker sends packets with 1329a fake source address/port but does not know the connection's sequence 1330numbers. 1331Similarly, 1332.Xr pf 4 1333knows how to match ICMP replies to states. 1334For example, 1335.Bd -literal -offset indent 1336pass out inet proto icmp all icmp-type echoreq 1337.Ed 1338.Pp 1339allows echo requests (such as those created by 1340.Xr ping 8 ) 1341out statefully, and matches incoming echo replies correctly to states. 1342.Pp 1343Also, looking up states is usually faster than evaluating rules. 1344If there are 50 rules, all of them are evaluated sequentially in O(n). 1345Even with 50000 states, only 16 comparisons are needed to match a 1346state, since states are stored in a binary search tree that allows 1347searches in O(log2 n). 1348.Pp 1349Furthermore, correct handling of ICMP error messages is critical to 1350many protocols, particularly TCP. 1351.Xr pf 4 1352matches ICMP error messages to the correct connection, checks them against 1353connection parameters, and passes them if appropriate. 1354For example if an ICMP source quench message referring to a stateful TCP 1355connection arrives, it will be matched to the state and get passed. 1356.Pp 1357Finally, state tracking is required for 1358.Ar nat , binat No and Ar rdr 1359rules, in order to track address and port translations and reverse the 1360translation on returning packets. 1361.Pp 1362.Xr pf 4 1363will also create state for other protocols which are effectively stateless by 1364nature. 1365UDP packets are matched to states using only host addresses and ports, 1366and other protocols are matched to states using only the host addresses. 1367.Pp 1368If stateless filtering of individual packets is desired, 1369the 1370.Ar no state 1371keyword can be used to specify that state will not be created 1372if this is the last matching rule. 1373A number of parameters can also be set to affect how 1374.Xr pf 4 1375handles state tracking. 1376See 1377.Sx STATEFUL TRACKING OPTIONS 1378below for further details. 1379.Sh PARAMETERS 1380The rule parameters specify the packets to which a rule applies. 1381A packet always comes in on, or goes out through, one interface. 1382Most parameters are optional. 1383If a parameter is specified, the rule only applies to packets with 1384matching attributes. 1385Certain parameters can be expressed as lists, in which case 1386.Xr pfctl 8 1387generates all needed rule combinations. 1388.Bl -tag -width xxxx 1389.It Ar in No or Ar out 1390This rule applies to incoming or outgoing packets. 1391If neither 1392.Ar in 1393nor 1394.Ar out 1395are specified, the rule will match packets in both directions. 1396.It Ar log 1397In addition to the action specified, a log message is generated. 1398Only the packet that establishes the state is logged, 1399unless the 1400.Ar no state 1401option is specified. 1402The logged packets are sent to a 1403.Xr pflog 4 1404interface, by default 1405.Ar pflog0 . 1406This interface is monitored by the 1407.Xr pflogd 8 1408logging daemon, which dumps the logged packets to the file 1409.Pa /var/log/pflog 1410in 1411.Xr pcap 3 1412binary format. 1413.It Ar log (all) 1414Used to force logging of all packets for a connection. 1415This is not necessary when 1416.Ar no state 1417is explicitly specified. 1418As with 1419.Ar log , 1420packets are logged to 1421.Xr pflog 4 . 1422.It Ar log (user) 1423Logs the 1424.Ux 1425user ID of the user that owns the socket and the PID of the process that 1426has the socket open where the packet is sourced from or destined to 1427(depending on which socket is local). 1428This is in addition to the normal information logged. 1429.Pp 1430Only the first packet 1431logged via 1432.Ar log (all, user) 1433will have the user credentials logged when using stateful matching. 1434.It Ar log (to Aq Ar interface ) 1435Send logs to the specified 1436.Xr pflog 4 1437interface instead of 1438.Ar pflog0 . 1439.It Ar quick 1440If a packet matches a rule which has the 1441.Ar quick 1442option set, this rule 1443is considered the last matching rule, and evaluation of subsequent rules 1444is skipped. 1445.It Ar on Aq Ar interface 1446This rule applies only to packets coming in on, or going out through, this 1447particular interface or interface group. 1448For more information on interface groups, 1449see the 1450.Ic group 1451keyword in 1452.Xr ifconfig 8 . 1453.It Aq Ar af 1454This rule applies only to packets of this address family. 1455Supported values are 1456.Ar inet 1457and 1458.Ar inet6 . 1459.It Ar proto Aq Ar protocol 1460This rule applies only to packets of this protocol. 1461Common protocols are 1462.Xr icmp 4 , 1463.Xr icmp6 4 , 1464.Xr tcp 4 , 1465and 1466.Xr udp 4 . 1467For a list of all the protocol name to number mappings used by 1468.Xr pfctl 8 , 1469see the file 1470.Pa /etc/protocols . 1471.It Xo 1472.Ar from Aq Ar source 1473.Ar port Aq Ar source 1474.Ar os Aq Ar source 1475.Ar to Aq Ar dest 1476.Ar port Aq Ar dest 1477.Xc 1478This rule applies only to packets with the specified source and destination 1479addresses and ports. 1480.Pp 1481Addresses can be specified in CIDR notation (matching netblocks), as 1482symbolic host names, interface names or interface group names, or as any 1483of the following keywords: 1484.Pp 1485.Bl -tag -width xxxxxxxxxxxxxx -compact 1486.It Ar any 1487Any address. 1488.It Ar no-route 1489Any address which is not currently routable. 1490.It Ar urpf-failed 1491Any source address that fails a unicast reverse path forwarding (URPF) 1492check, i.e. packets coming in on an interface other than that which holds 1493the route back to the packet's source address. 1494.It Aq Ar table 1495Any address that matches the given table. 1496.El 1497.Pp 1498Ranges of addresses are specified by using the 1499.Sq - 1500operator. 1501For instance: 1502.Dq 10.1.1.10 - 10.1.1.12 1503means all addresses from 10.1.1.10 to 10.1.1.12, 1504hence addresses 10.1.1.10, 10.1.1.11, and 10.1.1.12. 1505.Pp 1506Interface names and interface group names can have modifiers appended: 1507.Pp 1508.Bl -tag -width xxxxxxxxxxxx -compact 1509.It Ar :network 1510Translates to the network(s) attached to the interface. 1511.It Ar :broadcast 1512Translates to the interface's broadcast address(es). 1513.It Ar :peer 1514Translates to the point-to-point interface's peer address(es). 1515.It Ar :0 1516Do not include interface aliases. 1517.El 1518.Pp 1519Host names may also have the 1520.Ar :0 1521option appended to restrict the name resolution to the first of each 1522v4 and non-link-local v6 address found. 1523.Pp 1524Host name resolution and interface to address translation are done at 1525ruleset load-time. 1526When the address of an interface (or host name) changes (under DHCP or PPP, 1527for instance), the ruleset must be reloaded for the change to be reflected 1528in the kernel. 1529Surrounding the interface name (and optional modifiers) in parentheses 1530changes this behaviour. 1531When the interface name is surrounded by parentheses, the rule is 1532automatically updated whenever the interface changes its address. 1533The ruleset does not need to be reloaded. 1534This is especially useful with 1535.Ar nat . 1536.Pp 1537Ports can be specified either by number or by name. 1538For example, port 80 can be specified as 1539.Em www . 1540For a list of all port name to number mappings used by 1541.Xr pfctl 8 , 1542see the file 1543.Pa /etc/services . 1544.Pp 1545Ports and ranges of ports are specified by using these operators: 1546.Bd -literal -offset indent 1547= (equal) 1548!= (unequal) 1549\*(Lt (less than) 1550\*(Le (less than or equal) 1551\*(Gt (greater than) 1552\*(Ge (greater than or equal) 1553: (range including boundaries) 1554\*(Gt\*(Lt (range excluding boundaries) 1555\*(Lt\*(Gt (except range) 1556.Ed 1557.Pp 1558.Sq \*(Gt\*(Lt , 1559.Sq \*(Lt\*(Gt 1560and 1561.Sq \&: 1562are binary operators (they take two arguments). 1563For instance: 1564.Bl -tag -width Fl 1565.It Ar port 2000:2004 1566means 1567.Sq all ports \*(Ge 2000 and \*(Le 2004 , 1568hence ports 2000, 2001, 2002, 2003 and 2004. 1569.It Ar port 2000 \*(Gt\*(Lt 2004 1570means 1571.Sq all ports \*(Gt 2000 and \*(Lt 2004 , 1572hence ports 2001, 2002 and 2003. 1573.It Ar port 2000 \*(Lt\*(Gt 2004 1574means 1575.Sq all ports \*(Lt 2000 or \*(Gt 2004 , 1576hence ports 1-1999 and 2005-65535. 1577.El 1578.Pp 1579The operating system of the source host can be specified in the case of TCP 1580rules with the 1581.Ar OS 1582modifier. 1583See the 1584.Sx OPERATING SYSTEM FINGERPRINTING 1585section for more information. 1586.Pp 1587The host, port and OS specifications are optional, as in the following examples: 1588.Bd -literal -offset indent 1589pass in all 1590pass in from any to any 1591pass in proto tcp from any port \*(Le 1024 to any 1592pass in proto tcp from any to any port 25 1593pass in proto tcp from 10.0.0.0/8 port \*(Gt 1024 \e 1594 to ! 10.1.2.3 port != ssh 1595pass in proto tcp from any os "OpenBSD" 1596.Ed 1597.It Ar all 1598This is equivalent to "from any to any". 1599.It Ar group Aq Ar group 1600Similar to 1601.Ar user , 1602this rule only applies to packets of sockets owned by the specified group. 1603.It Ar user Aq Ar user 1604This rule only applies to packets of sockets owned by the specified user. 1605For outgoing connections initiated from the firewall, this is the user 1606that opened the connection. 1607For incoming connections to the firewall itself, this is the user that 1608listens on the destination port. 1609For forwarded connections, where the firewall is not a connection endpoint, 1610the user and group are 1611.Em unknown . 1612.Pp 1613All packets, both outgoing and incoming, of one connection are associated 1614with the same user and group. 1615Only TCP and UDP packets can be associated with users; for other protocols 1616these parameters are ignored. 1617.Pp 1618User and group refer to the effective (as opposed to the real) IDs, in 1619case the socket is created by a setuid/setgid process. 1620User and group IDs are stored when a socket is created; 1621when a process creates a listening socket as root (for instance, by 1622binding to a privileged port) and subsequently changes to another 1623user ID (to drop privileges), the credentials will remain root. 1624.Pp 1625User and group IDs can be specified as either numbers or names. 1626The syntax is similar to the one for ports. 1627The value 1628.Em unknown 1629matches packets of forwarded connections. 1630.Em unknown 1631can only be used with the operators 1632.Cm = 1633and 1634.Cm != . 1635Other constructs like 1636.Cm user \*(Ge unknown 1637are invalid. 1638Forwarded packets with unknown user and group ID match only rules 1639that explicitly compare against 1640.Em unknown 1641with the operators 1642.Cm = 1643or 1644.Cm != . 1645For instance 1646.Cm user \*(Ge 0 1647does not match forwarded packets. 1648The following example allows only selected users to open outgoing 1649connections: 1650.Bd -literal -offset indent 1651block out proto { tcp, udp } all 1652pass out proto { tcp, udp } all user { \*(Lt 1000, dhartmei } 1653.Ed 1654.It Xo Ar flags Aq Ar a 1655.Pf / Ns Aq Ar b 1656.No \*(Ba / Ns Aq Ar b 1657.No \*(Ba any 1658.Xc 1659This rule only applies to TCP packets that have the flags 1660.Aq Ar a 1661set out of set 1662.Aq Ar b . 1663Flags not specified in 1664.Aq Ar b 1665are ignored. 1666For stateful connections, the default is 1667.Ar flags S/SA . 1668To indicate that flags should not be checked at all, specify 1669.Ar flags any . 1670The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R. 1671.Bl -tag -width Fl 1672.It Ar flags S/S 1673Flag SYN is set. 1674The other flags are ignored. 1675.It Ar flags S/SA 1676This is the default setting for stateful connections. 1677Out of SYN and ACK, exactly SYN may be set. 1678SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not. 1679This is more restrictive than the previous example. 1680.It Ar flags /SFRA 1681If the first set is not specified, it defaults to none. 1682All of SYN, FIN, RST and ACK must be unset. 1683.El 1684.Pp 1685Because 1686.Ar flags S/SA 1687is applied by default (unless 1688.Ar no state 1689is specified), only the initial SYN packet of a TCP handshake will create 1690a state for a TCP connection. 1691It is possible to be less restrictive, and allow state creation from 1692intermediate 1693.Pq non-SYN 1694packets, by specifying 1695.Ar flags any . 1696This will cause 1697.Xr pf 4 1698to synchronize to existing connections, for instance 1699if one flushes the state table. 1700However, states created from such intermediate packets may be missing 1701connection details such as the TCP window scaling factor. 1702States which modify the packet flow, such as those affected by 1703.Ar nat , binat No or Ar rdr 1704rules, 1705.Ar modulate No or Ar synproxy state 1706options, or scrubbed with 1707.Ar reassemble tcp 1708will also not be recoverable from intermediate packets. 1709Such connections will stall and time out. 1710.It Xo Ar icmp-type Aq Ar type 1711.Ar code Aq Ar code 1712.Xc 1713.It Xo Ar icmp6-type Aq Ar type 1714.Ar code Aq Ar code 1715.Xc 1716This rule only applies to ICMP or ICMPv6 packets with the specified type 1717and code. 1718Text names for ICMP types and codes are listed in 1719.Xr icmp 4 1720and 1721.Xr icmp6 4 . 1722This parameter is only valid for rules that cover protocols ICMP or 1723ICMP6. 1724The protocol and the ICMP type indicator 1725.Po 1726.Ar icmp-type 1727or 1728.Ar icmp6-type 1729.Pc 1730must match. 1731.It Xo Ar tos Aq Ar string 1732.No \*(Ba Aq Ar number 1733.Xc 1734This rule applies to packets with the specified 1735.Em TOS 1736bits set. 1737.Em TOS 1738may be 1739given as one of 1740.Ar critical , 1741.Ar inetcontrol , 1742.Ar lowdelay , 1743.Ar netcontrol , 1744.Ar throughput , 1745.Ar reliability , 1746or one of the DiffServ Code Points: 1747.Ar ef , 1748.Ar va , 1749.Ar af11 No ... Ar af43 , 1750.Ar cs0 No ... Ar cs7 ; 1751or as either hex or decimal. 1752.Pp 1753For example, the following rules are identical: 1754.Bd -literal -offset indent 1755pass all tos lowdelay 1756pass all tos 0x10 1757pass all tos 16 1758.Ed 1759.It Ar allow-opts 1760By default, IPv4 packets with IP options or IPv6 packets with routing 1761extension headers are blocked. 1762When 1763.Ar allow-opts 1764is specified for a 1765.Ar pass 1766rule, packets that pass the filter based on that rule (last matching) 1767do so even if they contain IP options or routing extension headers. 1768For packets that match state, the rule that initially created the 1769state is used. 1770The implicit 1771.Ar pass 1772rule that is used when a packet does not match any rules does not 1773allow IP options. 1774.It Ar label Aq Ar string 1775Adds a label (name) to the rule, which can be used to identify the rule. 1776For instance, 1777pfctl -s labels 1778shows per-rule statistics for rules that have labels. 1779.Pp 1780The following macros can be used in labels: 1781.Pp 1782.Bl -tag -width $srcaddr -compact -offset indent 1783.It Ar $if 1784The interface. 1785.It Ar $srcaddr 1786The source IP address. 1787.It Ar $dstaddr 1788The destination IP address. 1789.It Ar $srcport 1790The source port specification. 1791.It Ar $dstport 1792The destination port specification. 1793.It Ar $proto 1794The protocol name. 1795.It Ar $nr 1796The rule number. 1797.El 1798.Pp 1799For example: 1800.Bd -literal -offset indent 1801ips = \&"{ 1.2.3.4, 1.2.3.5 }\&" 1802pass in proto tcp from any to $ips \e 1803 port \*(Gt 1023 label \&"$dstaddr:$dstport\&" 1804.Ed 1805.Pp 1806expands to 1807.Bd -literal -offset indent 1808pass in inet proto tcp from any to 1.2.3.4 \e 1809 port \*(Gt 1023 label \&"1.2.3.4:\*(Gt1023\&" 1810pass in inet proto tcp from any to 1.2.3.5 \e 1811 port \*(Gt 1023 label \&"1.2.3.5:\*(Gt1023\&" 1812.Ed 1813.Pp 1814The macro expansion for the 1815.Ar label 1816directive occurs only at configuration file parse time, not during runtime. 1817.It Xo Ar queue Aq Ar queue 1818.No \*(Ba ( Aq Ar queue , 1819.Aq Ar queue ) 1820.Xc 1821Packets matching this rule will be assigned to the specified queue. 1822If two queues are given, packets which have a 1823.Em TOS 1824of 1825.Em lowdelay 1826and TCP ACKs with no data payload will be assigned to the second one. 1827See 1828.Sx QUEUEING 1829for setup details. 1830.Pp 1831For example: 1832.Bd -literal -offset indent 1833pass in proto tcp to port 25 queue mail 1834pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio) 1835.Ed 1836.Pp 1837.It Cm set prio Ar priority | Pq Ar priority , priority 1838Packets matching this rule will be assigned a specific queueing priority. 1839Priorities are assigned as integers 0 through 7. 1840If the packet is transmitted on a 1841.Xr vlan 4 1842interface, the queueing priority will be written as the priority 1843code point in the 802.1Q VLAN header. 1844If two priorities are given, packets which have a TOS of 1845.Cm lowdelay 1846and TCP ACKs with no data payload will be assigned to the second one. 1847.Pp 1848For example: 1849.Bd -literal -offset indent 1850pass in proto tcp to port 25 set prio 2 1851pass in proto tcp to port 22 set prio (2, 5) 1852.Ed 1853.Pp 1854.It Ar tag Aq Ar string 1855Packets matching this rule will be tagged with the 1856specified string. 1857The tag acts as an internal marker that can be used to 1858identify these packets later on. 1859This can be used, for example, to provide trust between 1860interfaces and to determine if packets have been 1861processed by translation rules. 1862Tags are 1863.Qq sticky , 1864meaning that the packet will be tagged even if the rule 1865is not the last matching rule. 1866Further matching rules can replace the tag with a 1867new one but will not remove a previously applied tag. 1868A packet is only ever assigned one tag at a time. 1869Packet tagging can be done during 1870.Ar nat , 1871.Ar rdr , 1872or 1873.Ar binat 1874rules in addition to filter rules. 1875Tags take the same macros as labels (see above). 1876.It Ar tagged Aq Ar string 1877Used with filter, translation or scrub rules 1878to specify that packets must already 1879be tagged with the given tag in order to match the rule. 1880Inverse tag matching can also be done 1881by specifying the 1882.Cm !\& 1883operator before the 1884.Ar tagged 1885keyword. 1886.It Ar rtable Aq Ar number 1887Used to select an alternate routing table for the routing lookup. 1888Only effective before the route lookup happened, i.e. when filtering inbound. 1889.It Xo Ar divert-to Aq Ar host 1890.Ar port Aq Ar port 1891.Xc 1892Used to redirect packets to a local socket bound to 1893.Ar host 1894and 1895.Ar port . 1896The packets will not be modified, so 1897.Xr getsockname 2 1898on the socket will return the original destination address of the packet. 1899.It Ar divert-reply 1900Used to receive replies for sockets that are bound to addresses 1901which are not local to the machine. 1902See 1903.Xr setsockopt 2 1904for information on how to bind these sockets. 1905.It Ar probability Aq Ar number 1906A probability attribute can be attached to a rule, with a value set between 19070 and 1, bounds not included. 1908In that case, the rule will be honoured using the given probability value 1909only. 1910For example, the following rule will drop 20% of incoming ICMP packets: 1911.Bd -literal -offset indent 1912block in proto icmp probability 20% 1913.Ed 1914.It Ar prio Aq Ar number 1915Only match packets which have the given queueing priority assigned. 1916.Pp 1917.El 1918.Sh ROUTING 1919If a packet matches a rule with a route option set, the packet filter will 1920route the packet according to the type of route option. 1921When such a rule creates state, the route option is also applied to all 1922packets matching the same connection. 1923.Bl -tag -width xxxx 1924.It Ar route-to 1925The 1926.Ar route-to 1927option routes the packet to the specified interface with an optional address 1928for the next hop. 1929When a 1930.Ar route-to 1931rule creates state, only packets that pass in the same direction as the 1932filter rule specifies will be routed in this way. 1933Packets passing in the opposite direction (replies) are not affected 1934and are routed normally. 1935.It Ar reply-to 1936The 1937.Ar reply-to 1938option is similar to 1939.Ar route-to , 1940but routes packets that pass in the opposite direction (replies) to the 1941specified interface. 1942Opposite direction is only defined in the context of a state entry, and 1943.Ar reply-to 1944is useful only in rules that create state. 1945It can be used on systems with multiple external connections to 1946route all outgoing packets of a connection through the interface 1947the incoming connection arrived through (symmetric routing enforcement). 1948.It Ar dup-to 1949The 1950.Ar dup-to 1951option creates a duplicate of the packet and routes it like 1952.Ar route-to . 1953The original packet gets routed as it normally would. 1954.El 1955.Sh POOL OPTIONS 1956For 1957.Ar nat 1958and 1959.Ar rdr 1960rules, (as well as for the 1961.Ar route-to , 1962.Ar reply-to 1963and 1964.Ar dup-to 1965rule options) for which there is a single redirection address which has a 1966subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP 1967address), a variety of different methods for assigning this address can be 1968used: 1969.Bl -tag -width xxxx 1970.It Ar bitmask 1971The 1972.Ar bitmask 1973option applies the network portion of the redirection address to the address 1974to be modified (source with 1975.Ar nat , 1976destination with 1977.Ar rdr ) . 1978.It Ar random 1979The 1980.Ar random 1981option selects an address at random within the defined block of addresses. 1982.It Ar source-hash 1983The 1984.Ar source-hash 1985option uses a hash of the source address to determine the redirection address, 1986ensuring that the redirection address is always the same for a given source. 1987An optional key can be specified after this keyword either in hex or as a 1988string; by default 1989.Xr pfctl 8 1990randomly generates a key for source-hash every time the 1991ruleset is reloaded. 1992.It Ar round-robin 1993The 1994.Ar round-robin 1995option loops through the redirection address(es). 1996.Pp 1997When more than one redirection address is specified, 1998.Ar round-robin 1999is the only permitted pool type. 2000.It Ar static-port 2001With 2002.Ar nat 2003rules, the 2004.Ar static-port 2005option prevents 2006.Xr pf 4 2007from modifying the source port on TCP and UDP packets. 2008.It Xo Ar map-e-portset Aq Ar psid-offset 2009.No / Aq Ar psid-len 2010.No / Aq Ar psid 2011.Xc 2012With 2013.Ar nat 2014rules, the 2015.Ar map-e-portset 2016option enables the source port translation of MAP-E (RFC 7597) Customer Edge. 2017In order to make the host act as a MAP-E Customer Edge, setting up a tunneling 2018interface and pass rules for encapsulated packets are required in addition 2019to the map-e-portset nat rule. 2020.Pp 2021For example: 2022.Bd -literal -offset indent 2023nat on $gif_mape_if from $int_if:network to any \e 2024 -> $ipv4_mape_src map-e-portset 6/8/0x34 2025.Ed 2026.Pp 2027sets PSID offset 6, PSID length 8, PSID 0x34. 2028.Ed 2029.El 2030.Pp 2031Additionally, the 2032.Ar sticky-address 2033option can be specified to help ensure that multiple connections from the 2034same source are mapped to the same redirection address. 2035This option can be used with the 2036.Ar random 2037and 2038.Ar round-robin 2039pool options. 2040Note that by default these associations are destroyed as soon as there are 2041no longer states which refer to them; in order to make the mappings last 2042beyond the lifetime of the states, increase the global options with 2043.Ar set timeout src.track . 2044See 2045.Sx STATEFUL TRACKING OPTIONS 2046for more ways to control the source tracking. 2047.Sh STATE MODULATION 2048Much of the security derived from TCP is attributable to how well the 2049initial sequence numbers (ISNs) are chosen. 2050Some popular stack implementations choose 2051.Em very 2052poor ISNs and thus are normally susceptible to ISN prediction exploits. 2053By applying a 2054.Ar modulate state 2055rule to a TCP connection, 2056.Xr pf 4 2057will create a high quality random sequence number for each connection 2058endpoint. 2059.Pp 2060The 2061.Ar modulate state 2062directive implicitly keeps state on the rule and is 2063only applicable to TCP connections. 2064.Pp 2065For instance: 2066.Bd -literal -offset indent 2067block all 2068pass out proto tcp from any to any modulate state 2069pass in proto tcp from any to any port 25 flags S/SFRA modulate state 2070.Ed 2071.Pp 2072Note that modulated connections will not recover when the state table 2073is lost (firewall reboot, flushing the state table, etc...). 2074.Xr pf 4 2075will not be able to infer a connection again after the state table flushes 2076the connection's modulator. 2077When the state is lost, the connection may be left dangling until the 2078respective endpoints time out the connection. 2079It is possible on a fast local network for the endpoints to start an ACK 2080storm while trying to resynchronize after the loss of the modulator. 2081The default 2082.Ar flags 2083settings (or a more strict equivalent) should be used on 2084.Ar modulate state 2085rules to prevent ACK storms. 2086.Pp 2087Note that alternative methods are available 2088to prevent loss of the state table 2089and allow for firewall failover. 2090See 2091.Xr carp 4 2092and 2093.Xr pfsync 4 2094for further information. 2095.Sh SYN PROXY 2096By default, 2097.Xr pf 4 2098passes packets that are part of a 2099.Xr tcp 4 2100handshake between the endpoints. 2101The 2102.Ar synproxy state 2103option can be used to cause 2104.Xr pf 4 2105itself to complete the handshake with the active endpoint, perform a handshake 2106with the passive endpoint, and then forward packets between the endpoints. 2107.Pp 2108No packets are sent to the passive endpoint before the active endpoint has 2109completed the handshake, hence so-called SYN floods with spoofed source 2110addresses will not reach the passive endpoint, as the sender can't complete the 2111handshake. 2112.Pp 2113The proxy is transparent to both endpoints, they each see a single 2114connection from/to the other endpoint. 2115.Xr pf 4 2116chooses random initial sequence numbers for both handshakes. 2117Once the handshakes are completed, the sequence number modulators 2118(see previous section) are used to translate further packets of the 2119connection. 2120.Ar synproxy state 2121includes 2122.Ar modulate state . 2123.Pp 2124Rules with 2125.Ar synproxy 2126will not work if 2127.Xr pf 4 2128operates on a 2129.Xr bridge 4 . 2130.Pp 2131Example: 2132.Bd -literal -offset indent 2133pass in proto tcp from any to any port www synproxy state 2134.Ed 2135.Sh STATEFUL TRACKING OPTIONS 2136A number of options related to stateful tracking can be applied on a 2137per-rule basis. 2138.Ar keep state , 2139.Ar modulate state 2140and 2141.Ar synproxy state 2142support these options, and 2143.Ar keep state 2144must be specified explicitly to apply options to a rule. 2145.Pp 2146.Bl -tag -width xxxx -compact 2147.It Ar max Aq Ar number 2148Limits the number of concurrent states the rule may create. 2149When this limit is reached, further packets that would create 2150state will not match this rule until existing states time out. 2151.It Ar no-sync 2152Prevent state changes for states created by this rule from appearing on the 2153.Xr pfsync 4 2154interface. 2155.It Xo Aq Ar timeout 2156.Aq Ar seconds 2157.Xc 2158Changes the timeout values used for states created by this rule. 2159For a list of all valid timeout names, see 2160.Sx OPTIONS 2161above. 2162.It Ar sloppy 2163Uses a sloppy TCP connection tracker that does not check sequence 2164numbers at all, which makes insertion and ICMP teardown attacks way 2165easier. 2166This is intended to be used in situations where one does not see all 2167packets of a connection, e.g. in asymmetric routing situations. 2168Cannot be used with modulate or synproxy state. 2169.El 2170.Pp 2171Multiple options can be specified, separated by commas: 2172.Bd -literal -offset indent 2173pass in proto tcp from any to any \e 2174 port www keep state \e 2175 (max 100, source-track rule, max-src-nodes 75, \e 2176 max-src-states 3, tcp.established 60, tcp.closing 5) 2177.Ed 2178.Pp 2179When the 2180.Ar source-track 2181keyword is specified, the number of states per source IP is tracked. 2182.Pp 2183.Bl -tag -width xxxx -compact 2184.It Ar source-track rule 2185The maximum number of states created by this rule is limited by the rule's 2186.Ar max-src-nodes 2187and 2188.Ar max-src-states 2189options. 2190Only state entries created by this particular rule count toward the rule's 2191limits. 2192.It Ar source-track global 2193The number of states created by all rules that use this option is limited. 2194Each rule can specify different 2195.Ar max-src-nodes 2196and 2197.Ar max-src-states 2198options, however state entries created by any participating rule count towards 2199each individual rule's limits. 2200.El 2201.Pp 2202The following limits can be set: 2203.Pp 2204.Bl -tag -width xxxx -compact 2205.It Ar max-src-nodes Aq Ar number 2206Limits the maximum number of source addresses which can simultaneously 2207have state table entries. 2208.It Ar max-src-states Aq Ar number 2209Limits the maximum number of simultaneous state entries that a single 2210source address can create with this rule. 2211.El 2212.Pp 2213For stateful TCP connections, limits on established connections (connections 2214which have completed the TCP 3-way handshake) can also be enforced 2215per source IP. 2216.Pp 2217.Bl -tag -width xxxx -compact 2218.It Ar max-src-conn Aq Ar number 2219Limits the maximum number of simultaneous TCP connections which have 2220completed the 3-way handshake that a single host can make. 2221.It Xo Ar max-src-conn-rate Aq Ar number 2222.No / Aq Ar seconds 2223.Xc 2224Limit the rate of new connections over a time interval. 2225The connection rate is an approximation calculated as a moving average. 2226.El 2227.Pp 2228Because the 3-way handshake ensures that the source address is not being 2229spoofed, more aggressive action can be taken based on these limits. 2230With the 2231.Ar overload Aq Ar table 2232state option, source IP addresses which hit either of the limits on 2233established connections will be added to the named table. 2234This table can be used in the ruleset to block further activity from 2235the offending host, redirect it to a tarpit process, or restrict its 2236bandwidth. 2237.Pp 2238The optional 2239.Ar flush 2240keyword kills all states created by the matching rule which originate 2241from the host which exceeds these limits. 2242The 2243.Ar global 2244modifier to the flush command kills all states originating from the 2245offending host, regardless of which rule created the state. 2246.Pp 2247For example, the following rules will protect the webserver against 2248hosts making more than 100 connections in 10 seconds. 2249Any host which connects faster than this rate will have its address added 2250to the 2251.Aq bad_hosts 2252table and have all states originating from it flushed. 2253Any new packets arriving from this host will be dropped unconditionally 2254by the block rule. 2255.Bd -literal -offset indent 2256block quick from \*(Ltbad_hosts\*(Gt 2257pass in on $ext_if proto tcp to $webserver port www keep state \e 2258 (max-src-conn-rate 100/10, overload \*(Ltbad_hosts\*(Gt flush global) 2259.Ed 2260.Sh OPERATING SYSTEM FINGERPRINTING 2261Passive OS Fingerprinting is a mechanism to inspect nuances of a TCP 2262connection's initial SYN packet and guess at the host's operating system. 2263Unfortunately these nuances are easily spoofed by an attacker so the 2264fingerprint is not useful in making security decisions. 2265But the fingerprint is typically accurate enough to make policy decisions 2266upon. 2267.Pp 2268The fingerprints may be specified by operating system class, by 2269version, or by subtype/patchlevel. 2270The class of an operating system is typically the vendor or genre 2271and would be 2272.Ox 2273for the 2274.Xr pf 4 2275firewall itself. 2276The version of the oldest available 2277.Ox 2278release on the main FTP site 2279would be 2.6 and the fingerprint would be written 2280.Pp 2281.Dl \&"OpenBSD 2.6\&" 2282.Pp 2283The subtype of an operating system is typically used to describe the 2284patchlevel if that patch led to changes in the TCP stack behavior. 2285In the case of 2286.Ox , 2287the only subtype is for a fingerprint that was 2288normalized by the 2289.Ar no-df 2290scrub option and would be specified as 2291.Pp 2292.Dl \&"OpenBSD 3.3 no-df\&" 2293.Pp 2294Fingerprints for most popular operating systems are provided by 2295.Xr pf.os 5 . 2296Once 2297.Xr pf 4 2298is running, a complete list of known operating system fingerprints may 2299be listed by running: 2300.Pp 2301.Dl # pfctl -so 2302.Pp 2303Filter rules can enforce policy at any level of operating system specification 2304assuming a fingerprint is present. 2305Policy could limit traffic to approved operating systems or even ban traffic 2306from hosts that aren't at the latest service pack. 2307.Pp 2308The 2309.Ar unknown 2310class can also be used as the fingerprint which will match packets for 2311which no operating system fingerprint is known. 2312.Pp 2313Examples: 2314.Bd -literal -offset indent 2315pass out proto tcp from any os OpenBSD 2316block out proto tcp from any os Doors 2317block out proto tcp from any os "Doors PT" 2318block out proto tcp from any os "Doors PT SP3" 2319block out from any os "unknown" 2320pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" 2321.Ed 2322.Pp 2323Operating system fingerprinting is limited only to the TCP SYN packet. 2324This means that it will not work on other protocols and will not match 2325a currently established connection. 2326.Pp 2327Caveat: operating system fingerprints are occasionally wrong. 2328There are three problems: an attacker can trivially craft his packets to 2329appear as any operating system he chooses; 2330an operating system patch could change the stack behavior and no fingerprints 2331will match it until the database is updated; 2332and multiple operating systems may have the same fingerprint. 2333.Sh BLOCKING SPOOFED TRAFFIC 2334"Spoofing" is the faking of IP addresses, typically for malicious 2335purposes. 2336The 2337.Ar antispoof 2338directive expands to a set of filter rules which will block all 2339traffic with a source IP from the network(s) directly connected 2340to the specified interface(s) from entering the system through 2341any other interface. 2342.Pp 2343For example, the line 2344.Bd -literal -offset indent 2345antispoof for lo0 2346.Ed 2347.Pp 2348expands to 2349.Bd -literal -offset indent 2350block drop in on ! lo0 inet from 127.0.0.1/8 to any 2351block drop in on ! lo0 inet6 from ::1 to any 2352.Ed 2353.Pp 2354For non-loopback interfaces, there are additional rules to block incoming 2355packets with a source IP address identical to the interface's IP(s). 2356For example, assuming the interface wi0 had an IP address of 10.0.0.1 and a 2357netmask of 255.255.255.0, 2358the line 2359.Bd -literal -offset indent 2360antispoof for wi0 inet 2361.Ed 2362.Pp 2363expands to 2364.Bd -literal -offset indent 2365block drop in on ! wi0 inet from 10.0.0.0/24 to any 2366block drop in inet from 10.0.0.1 to any 2367.Ed 2368.Pp 2369Caveat: Rules created by the 2370.Ar antispoof 2371directive interfere with packets sent over loopback interfaces 2372to local addresses. 2373One should pass these explicitly. 2374.Sh FRAGMENT HANDLING 2375The size of IP datagrams (packets) can be significantly larger than the 2376maximum transmission unit (MTU) of the network. 2377In cases when it is necessary or more efficient to send such large packets, 2378the large packet will be fragmented into many smaller packets that will each 2379fit onto the wire. 2380Unfortunately for a firewalling device, only the first logical fragment will 2381contain the necessary header information for the subprotocol that allows 2382.Xr pf 4 2383to filter on things such as TCP ports or to perform NAT. 2384.Pp 2385Besides the use of 2386.Ar scrub 2387rules as described in 2388.Sx TRAFFIC NORMALIZATION 2389above, there are three options for handling fragments in the packet filter. 2390.Pp 2391One alternative is to filter individual fragments with filter rules. 2392If no 2393.Ar scrub 2394rule applies to a fragment, it is passed to the filter. 2395Filter rules with matching IP header parameters decide whether the 2396fragment is passed or blocked, in the same way as complete packets 2397are filtered. 2398Without reassembly, fragments can only be filtered based on IP header 2399fields (source/destination address, protocol), since subprotocol header 2400fields are not available (TCP/UDP port numbers, ICMP code/type). 2401The 2402.Ar fragment 2403option can be used to restrict filter rules to apply only to 2404fragments, but not complete packets. 2405Filter rules without the 2406.Ar fragment 2407option still apply to fragments, if they only specify IP header fields. 2408For instance, the rule 2409.Bd -literal -offset indent 2410pass in proto tcp from any to any port 80 2411.Ed 2412.Pp 2413never applies to a fragment, even if the fragment is part of a TCP 2414packet with destination port 80, because without reassembly this information 2415is not available for each fragment. 2416This also means that fragments cannot create new or match existing 2417state table entries, which makes stateful filtering and address 2418translation (NAT, redirection) for fragments impossible. 2419.Pp 2420It's also possible to reassemble only certain fragments by specifying 2421source or destination addresses or protocols as parameters in 2422.Ar scrub 2423rules. 2424.Pp 2425In most cases, the benefits of reassembly outweigh the additional 2426memory cost, and it's recommended to use 2427.Ar scrub 2428rules to reassemble 2429all fragments via the 2430.Ar fragment reassemble 2431modifier. 2432.Pp 2433The memory allocated for fragment caching can be limited using 2434.Xr pfctl 8 . 2435Once this limit is reached, fragments that would have to be cached 2436are dropped until other entries time out. 2437The timeout value can also be adjusted. 2438.Pp 2439When forwarding reassembled IPv6 packets, pf refragments them with 2440the original maximum fragment size. 2441This allows the sender to determine the optimal fragment size by 2442path MTU discovery. 2443.Sh ANCHORS 2444Besides the main ruleset, 2445.Xr pfctl 8 2446can load rulesets into 2447.Ar anchor 2448attachment points. 2449An 2450.Ar anchor 2451is a container that can hold rules, address tables, and other anchors. 2452.Pp 2453An 2454.Ar anchor 2455has a name which specifies the path where 2456.Xr pfctl 8 2457can be used to access the anchor to perform operations on it, such as 2458attaching child anchors to it or loading rules into it. 2459Anchors may be nested, with components separated by 2460.Sq / 2461characters, similar to how file system hierarchies are laid out. 2462The main ruleset is actually the default anchor, so filter and 2463translation rules, for example, may also be contained in any anchor. 2464.Pp 2465An anchor can reference another 2466.Ar anchor 2467attachment point 2468using the following kinds 2469of rules: 2470.Bl -tag -width xxxx 2471.It Ar nat-anchor Aq Ar name 2472Evaluates the 2473.Ar nat 2474rules in the specified 2475.Ar anchor . 2476.It Ar rdr-anchor Aq Ar name 2477Evaluates the 2478.Ar rdr 2479rules in the specified 2480.Ar anchor . 2481.It Ar binat-anchor Aq Ar name 2482Evaluates the 2483.Ar binat 2484rules in the specified 2485.Ar anchor . 2486.It Ar anchor Aq Ar name 2487Evaluates the filter rules in the specified 2488.Ar anchor . 2489.It Xo Ar load anchor 2490.Aq Ar name 2491.Ar from Aq Ar file 2492.Xc 2493Loads the rules from the specified file into the 2494anchor 2495.Ar name . 2496.El 2497.Pp 2498When evaluation of the main ruleset reaches an 2499.Ar anchor 2500rule, 2501.Xr pf 4 2502will proceed to evaluate all rules specified in that anchor. 2503.Pp 2504Matching filter and translation rules marked with the 2505.Ar quick 2506option are final and abort the evaluation of the rules in other 2507anchors and the main ruleset. 2508If the 2509.Ar anchor 2510itself is marked with the 2511.Ar quick 2512option, 2513ruleset evaluation will terminate when the anchor is exited if the packet is 2514matched by any rule within the anchor. 2515.Pp 2516.Ar anchor 2517rules are evaluated relative to the anchor in which they are contained. 2518For example, all 2519.Ar anchor 2520rules specified in the main ruleset will reference anchor 2521attachment points underneath the main ruleset, and 2522.Ar anchor 2523rules specified in a file loaded from a 2524.Ar load anchor 2525rule will be attached under that anchor point. 2526.Pp 2527Rules may be contained in 2528.Ar anchor 2529attachment points which do not contain any rules when the main ruleset 2530is loaded, and later such anchors can be manipulated through 2531.Xr pfctl 8 2532without reloading the main ruleset or other anchors. 2533For example, 2534.Bd -literal -offset indent 2535ext_if = \&"kue0\&" 2536block on $ext_if all 2537anchor spam 2538pass out on $ext_if all 2539pass in on $ext_if proto tcp from any \e 2540 to $ext_if port smtp 2541.Ed 2542.Pp 2543blocks all packets on the external interface by default, then evaluates 2544all rules in the 2545.Ar anchor 2546named "spam", and finally passes all outgoing connections and 2547incoming connections to port 25. 2548.Bd -literal -offset indent 2549# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e 2550 pfctl -a spam -f - 2551.Ed 2552.Pp 2553This loads a single rule into the 2554.Ar anchor , 2555which blocks all packets from a specific address. 2556.Pp 2557The anchor can also be populated by adding a 2558.Ar load anchor 2559rule after the 2560.Ar anchor 2561rule: 2562.Bd -literal -offset indent 2563anchor spam 2564load anchor spam from "/etc/pf-spam.conf" 2565.Ed 2566.Pp 2567When 2568.Xr pfctl 8 2569loads 2570.Nm pf.conf , 2571it will also load all the rules from the file 2572.Pa /etc/pf-spam.conf 2573into the anchor. 2574.Pp 2575Optionally, 2576.Ar anchor 2577rules can specify packet filtering parameters using the same syntax as 2578filter rules. 2579When parameters are used, the 2580.Ar anchor 2581rule is only evaluated for matching packets. 2582This allows conditional evaluation of anchors, like: 2583.Bd -literal -offset indent 2584block on $ext_if all 2585anchor spam proto tcp from any to any port smtp 2586pass out on $ext_if all 2587pass in on $ext_if proto tcp from any to $ext_if port smtp 2588.Ed 2589.Pp 2590The rules inside 2591.Ar anchor 2592spam are only evaluated for 2593.Ar tcp 2594packets with destination port 25. 2595Hence, 2596.Bd -literal -offset indent 2597# echo \&"block in quick from 1.2.3.4 to any" \&| \e 2598 pfctl -a spam -f - 2599.Ed 2600.Pp 2601will only block connections from 1.2.3.4 to port 25. 2602.Pp 2603Anchors may end with the asterisk 2604.Pq Sq * 2605character, which signifies that all anchors attached at that point 2606should be evaluated in the alphabetical ordering of their anchor name. 2607For example, 2608.Bd -literal -offset indent 2609anchor "spam/*" 2610.Ed 2611.Pp 2612will evaluate each rule in each anchor attached to the 2613.Li spam 2614anchor. 2615Note that it will only evaluate anchors that are directly attached to the 2616.Li spam 2617anchor, and will not descend to evaluate anchors recursively. 2618.Pp 2619Since anchors are evaluated relative to the anchor in which they are 2620contained, there is a mechanism for accessing the parent and ancestor 2621anchors of a given anchor. 2622Similar to file system path name resolution, if the sequence 2623.Dq .. 2624appears as an anchor path component, the parent anchor of the current 2625anchor in the path evaluation at that point will become the new current 2626anchor. 2627As an example, consider the following: 2628.Bd -literal -offset indent 2629# echo ' anchor "spam/allowed" ' | pfctl -f - 2630# echo -e ' anchor "../banned" \en pass' | \e 2631 pfctl -a spam/allowed -f - 2632.Ed 2633.Pp 2634Evaluation of the main ruleset will lead into the 2635.Li spam/allowed 2636anchor, which will evaluate the rules in the 2637.Li spam/banned 2638anchor, if any, before finally evaluating the 2639.Ar pass 2640rule. 2641.Pp 2642Filter rule 2643.Ar anchors 2644can also be loaded inline in the ruleset within a brace ('{' '}') delimited 2645block. 2646Brace delimited blocks may contain rules or other brace-delimited blocks. 2647When anchors are loaded this way the anchor name becomes optional. 2648.Bd -literal -offset indent 2649anchor "external" on $ext_if { 2650 block 2651 anchor out { 2652 pass proto tcp from any to port { 25, 80, 443 } 2653 } 2654 pass in proto tcp to any port 22 2655} 2656.Ed 2657.Pp 2658Since the parser specification for anchor names is a string, any 2659reference to an anchor name containing 2660.Sq / 2661characters will require double quote 2662.Pq Sq \&" 2663characters around the anchor name. 2664.Sh TRANSLATION EXAMPLES 2665This example maps incoming requests on port 80 to port 8080, on 2666which a daemon is running (because, for example, it is not run as root, 2667and therefore lacks permission to bind to port 80). 2668.Bd -literal 2669# use a macro for the interface name, so it can be changed easily 2670ext_if = \&"ne3\&" 2671 2672# map daemon on 8080 to appear to be on 80 2673rdr on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 port 8080 2674.Ed 2675.Pp 2676If the 2677.Ar pass 2678modifier is given, packets matching the translation rule are passed without 2679inspecting the filter rules: 2680.Bd -literal 2681rdr pass on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 \e 2682 port 8080 2683.Ed 2684.Pp 2685In the example below, vlan12 is configured as 192.168.168.1; 2686the machine translates all packets coming from 192.168.168.0/24 to 204.92.77.111 2687when they are going out any interface except vlan12. 2688This has the net effect of making traffic from the 192.168.168.0/24 2689network appear as though it is the Internet routable address 2690204.92.77.111 to nodes behind any interface on the router except 2691for the nodes on vlan12. 2692(Thus, 192.168.168.1 can talk to the 192.168.168.0/24 nodes.) 2693.Bd -literal 2694nat on ! vlan12 from 192.168.168.0/24 to any -\*(Gt 204.92.77.111 2695.Ed 2696.Pp 2697In the example below, the machine sits between a fake internal 144.19.74.* 2698network, and a routable external IP of 204.92.77.100. 2699The 2700.Ar no nat 2701rule excludes protocol AH from being translated. 2702.Bd -literal 2703# NO NAT 2704no nat on $ext_if proto ah from 144.19.74.0/24 to any 2705nat on $ext_if from 144.19.74.0/24 to any -\*(Gt 204.92.77.100 2706.Ed 2707.Pp 2708In the example below, packets bound for one specific server, as well as those 2709generated by the sysadmins are not proxied; all other connections are. 2710.Bd -literal 2711# NO RDR 2712no rdr on $int_if proto { tcp, udp } from any to $server port 80 2713no rdr on $int_if proto { tcp, udp } from $sysadmins to any port 80 2714rdr on $int_if proto { tcp, udp } from any to any port 80 -\*(Gt 127.0.0.1 \e 2715 port 80 2716.Ed 2717.Pp 2718This longer example uses both a NAT and a redirection. 2719The external interface has the address 157.161.48.183. 2720On localhost, we are running 2721.Xr ftp-proxy 8 , 2722waiting for FTP sessions to be redirected to it. 2723The three mandatory anchors for 2724.Xr ftp-proxy 8 2725are omitted from this example; see the 2726.Xr ftp-proxy 8 2727manpage. 2728.Bd -literal 2729# NAT 2730# Translate outgoing packets' source addresses (any protocol). 2731# In this case, any address but the gateway's external address is mapped. 2732nat on $ext_if inet from ! ($ext_if) to any -\*(Gt ($ext_if) 2733 2734# NAT PROXYING 2735# Map outgoing packets' source port to an assigned proxy port instead of 2736# an arbitrary port. 2737# In this case, proxy outgoing isakmp with port 500 on the gateway. 2738nat on $ext_if inet proto udp from any port = isakmp to any -\*(Gt ($ext_if) \e 2739 port 500 2740 2741# BINAT 2742# Translate outgoing packets' source address (any protocol). 2743# Translate incoming packets' destination address to an internal machine 2744# (bidirectional). 2745binat on $ext_if from 10.1.2.150 to any -\*(Gt $ext_if 2746 2747# RDR 2748# Translate incoming packets' destination addresses. 2749# As an example, redirect a TCP and UDP port to an internal machine. 2750rdr on $ext_if inet proto tcp from any to ($ext_if) port 8080 \e 2751 -\*(Gt 10.1.2.151 port 22 2752rdr on $ext_if inet proto udp from any to ($ext_if) port 8080 \e 2753 -\*(Gt 10.1.2.151 port 53 2754 2755# RDR 2756# Translate outgoing ftp control connections to send them to localhost 2757# for proxying with ftp-proxy(8) running on port 8021. 2758rdr on $int_if proto tcp from any to any port 21 -\*(Gt 127.0.0.1 port 8021 2759.Ed 2760.Pp 2761In this example, a NAT gateway is set up to translate internal addresses 2762using a pool of public addresses (192.0.2.16/28) and to redirect 2763incoming web server connections to a group of web servers on the internal 2764network. 2765.Bd -literal 2766# NAT LOAD BALANCE 2767# Translate outgoing packets' source addresses using an address pool. 2768# A given source address is always translated to the same pool address by 2769# using the source-hash keyword. 2770nat on $ext_if inet from any to any -\*(Gt 192.0.2.16/28 source-hash 2771 2772# RDR ROUND ROBIN 2773# Translate incoming web server connections to a group of web servers on 2774# the internal network. 2775rdr on $ext_if proto tcp from any to any port 80 \e 2776 -\*(Gt { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin 2777.Ed 2778.Sh FILTER EXAMPLES 2779.Bd -literal 2780# The external interface is kue0 2781# (157.161.48.183, the only routable address) 2782# and the private network is 10.0.0.0/8, for which we are doing NAT. 2783 2784# use a macro for the interface name, so it can be changed easily 2785ext_if = \&"kue0\&" 2786 2787# normalize all incoming traffic 2788scrub in on $ext_if all fragment reassemble 2789 2790# block and log everything by default 2791block return log on $ext_if all 2792 2793# block anything coming from source we have no back routes for 2794block in from no-route to any 2795 2796# block packets whose ingress interface does not match the one in 2797# the route back to their source address 2798block in from urpf-failed to any 2799 2800# block and log outgoing packets that do not have our address as source, 2801# they are either spoofed or something is misconfigured (NAT disabled, 2802# for instance), we want to be nice and do not send out garbage. 2803block out log quick on $ext_if from ! 157.161.48.183 to any 2804 2805# silently drop broadcasts (cable modem noise) 2806block in quick on $ext_if from any to 255.255.255.255 2807 2808# block and log incoming packets from reserved address space and invalid 2809# addresses, they are either spoofed or misconfigured, we cannot reply to 2810# them anyway (hence, no return-rst). 2811block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e 2812 192.168.0.0/16, 255.255.255.255/32 } to any 2813 2814# ICMP 2815 2816# pass out/in certain ICMP queries and keep state (ping) 2817# state matching is done on host addresses and ICMP id (not type/code), 2818# so replies (like 0/0 for 8/0) will match queries 2819# ICMP error messages (which always refer to a TCP/UDP packet) are 2820# handled by the TCP/UDP states 2821pass on $ext_if inet proto icmp all icmp-type 8 code 0 2822 2823# UDP 2824 2825# pass out all UDP connections and keep state 2826pass out on $ext_if proto udp all 2827 2828# pass in certain UDP connections and keep state (DNS) 2829pass in on $ext_if proto udp from any to any port domain 2830 2831# TCP 2832 2833# pass out all TCP connections and modulate state 2834pass out on $ext_if proto tcp all modulate state 2835 2836# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT) 2837pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e 2838 auth } 2839 2840# Do not allow Windows 9x SMTP connections since they are typically 2841# a viral worm. Alternately we could limit these OSes to 1 connection each. 2842block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e 2843 to any port smtp 2844 2845# IPv6 2846# pass in/out all IPv6 traffic: note that we have to enable this in two 2847# different ways, on both our physical interface and our tunnel 2848pass quick on gif0 inet6 2849pass quick on $ext_if proto ipv6 2850 2851# Packet Tagging 2852 2853# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is 2854# being done on $ext_if for all outgoing packets. tag packets in on 2855# $int_if and pass those tagged packets out on $ext_if. all other 2856# outgoing packets (i.e., packets from the wireless network) are only 2857# permitted to access port 80. 2858 2859pass in on $int_if from any to any tag INTNET 2860pass in on $wifi_if from any to any 2861 2862block out on $ext_if from any to any 2863pass out quick on $ext_if tagged INTNET 2864pass out on $ext_if proto tcp from any to any port 80 2865 2866# tag incoming packets as they are redirected to spamd(8). use the tag 2867# to pass those packets through the packet filter. 2868 2869rdr on $ext_if inet proto tcp from \*(Ltspammers\*(Gt to port smtp \e 2870 tag SPAMD -\*(Gt 127.0.0.1 port spamd 2871 2872block in on $ext_if 2873pass in on $ext_if inet proto tcp tagged SPAMD 2874.Ed 2875.Sh GRAMMAR 2876Syntax for 2877.Nm 2878in BNF: 2879.Bd -literal 2880line = ( option | pf-rule | nat-rule | binat-rule | rdr-rule | 2881 antispoof-rule | altq-rule | queue-rule | trans-anchors | 2882 anchor-rule | anchor-close | load-anchor | table-rule | 2883 include ) 2884 2885option = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] | 2886 [ "ruleset-optimization" [ "none" | "basic" | "profile" ]] | 2887 [ "optimization" [ "default" | "normal" | 2888 "high-latency" | "satellite" | 2889 "aggressive" | "conservative" ] ] 2890 [ "limit" ( limit-item | "{" limit-list "}" ) ] | 2891 [ "loginterface" ( interface-name | "none" ) ] | 2892 [ "block-policy" ( "drop" | "return" ) ] | 2893 [ "state-policy" ( "if-bound" | "floating" ) ] 2894 [ "state-defaults" state-opts ] 2895 [ "require-order" ( "yes" | "no" ) ] 2896 [ "fingerprints" filename ] | 2897 [ "skip on" ifspec ] | 2898 [ "debug" ( "none" | "urgent" | "misc" | "loud" ) ] 2899 [ "keepcounters" ] ) 2900 2901pf-rule = action [ ( "in" | "out" ) ] 2902 [ "log" [ "(" logopts ")"] ] [ "quick" ] 2903 [ "on" ifspec ] [ route ] [ af ] [ protospec ] 2904 hosts [ filteropt-list ] 2905 2906logopts = logopt [ "," logopts ] 2907logopt = "all" | "user" | "to" interface-name 2908 2909filteropt-list = filteropt-list filteropt | filteropt 2910filteropt = user | group | flags | icmp-type | icmp6-type | "tos" tos | 2911 ( "no" | "keep" | "modulate" | "synproxy" ) "state" 2912 [ "(" state-opts ")" ] | 2913 "fragment" | "no-df" | "min-ttl" number | "set-tos" tos | 2914 "max-mss" number | "random-id" | "reassemble tcp" | 2915 fragmentation | "allow-opts" | 2916 "label" string | "tag" string | [ ! ] "tagged" string | 2917 "set prio" ( number | "(" number [ [ "," ] number ] ")" ) | 2918 "queue" ( string | "(" string [ [ "," ] string ] ")" ) | 2919 "rtable" number | "probability" number"%" | "prio" number 2920 2921nat-rule = [ "no" ] "nat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2922 [ "on" ifspec ] [ af ] 2923 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 2924 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" ) 2925 [ portspec ] [ pooltype ] [ "static-port" ] 2926 [ "map-e-portset" number "/" number "/" number ] ] 2927 2928binat-rule = [ "no" ] "binat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2929 [ "on" interface-name ] [ af ] 2930 [ "proto" ( proto-name | proto-number ) ] 2931 "from" address [ "/" mask-bits ] "to" ipspec 2932 [ "tag" string ] [ "tagged" string ] 2933 [ "-\*(Gt" address [ "/" mask-bits ] ] 2934 2935rdr-rule = [ "no" ] "rdr" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2936 [ "on" ifspec ] [ af ] 2937 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 2938 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" ) 2939 [ portspec ] [ pooltype ] ] 2940 2941antispoof-rule = "antispoof" [ "log" ] [ "quick" ] 2942 "for" ifspec [ af ] [ "label" string ] 2943 2944table-rule = "table" "\*(Lt" string "\*(Gt" [ tableopts-list ] 2945tableopts-list = tableopts-list tableopts | tableopts 2946tableopts = "persist" | "const" | "counters" | "file" string | 2947 "{" [ tableaddr-list ] "}" 2948tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec 2949tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ] 2950tableaddr = hostname | ifspec | "self" | 2951 ipv4-dotted-quad | ipv6-coloned-hex 2952 2953altq-rule = "altq on" interface-name queueopts-list 2954 "queue" subqueue 2955queue-rule = "queue" string [ "on" interface-name ] queueopts-list 2956 subqueue 2957 2958anchor-rule = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ] 2959 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ] 2960 2961anchor-close = "}" 2962 2963trans-anchors = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string 2964 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ] 2965 2966load-anchor = "load anchor" string "from" filename 2967 2968queueopts-list = queueopts-list queueopts | queueopts 2969queueopts = [ "bandwidth" bandwidth-spec ] | 2970 [ "qlimit" number ] | [ "tbrsize" number ] | 2971 [ "priority" number ] | [ schedulers ] 2972schedulers = ( cbq-def | priq-def | hfsc-def ) 2973bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" ) 2974 2975action = "pass" | "block" [ return ] | [ "no" ] "scrub" 2976return = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] | 2977 "return-icmp" [ "(" icmpcode [ [ "," ] icmp6code ] ")" ] | 2978 "return-icmp6" [ "(" icmp6code ")" ] 2979icmpcode = ( icmp-code-name | icmp-code-number ) 2980icmp6code = ( icmp6-code-name | icmp6-code-number ) 2981 2982ifspec = ( [ "!" ] ( interface-name | interface-group ) ) | 2983 "{" interface-list "}" 2984interface-list = [ "!" ] ( interface-name | interface-group ) 2985 [ [ "," ] interface-list ] 2986route = ( "route-to" | "reply-to" | "dup-to" ) 2987 ( routehost | "{" routehost-list "}" ) 2988 [ pooltype ] 2989af = "inet" | "inet6" 2990 2991protospec = "proto" ( proto-name | proto-number | 2992 "{" proto-list "}" ) 2993proto-list = ( proto-name | proto-number ) [ [ "," ] proto-list ] 2994 2995hosts = "all" | 2996 "from" ( "any" | "no-route" | "urpf-failed" | "self" | host | 2997 "{" host-list "}" ) [ port ] [ os ] 2998 "to" ( "any" | "no-route" | "self" | host | 2999 "{" host-list "}" ) [ port ] 3000 3001ipspec = "any" | host | "{" host-list "}" 3002host = [ "!" ] ( address [ "/" mask-bits ] | "\*(Lt" string "\*(Gt" ) 3003redirhost = address [ "/" mask-bits ] 3004routehost = "(" interface-name [ address [ "/" mask-bits ] ] ")" 3005address = ( interface-name | interface-group | 3006 "(" ( interface-name | interface-group ) ")" | 3007 hostname | ipv4-dotted-quad | ipv6-coloned-hex ) 3008host-list = host [ [ "," ] host-list ] 3009redirhost-list = redirhost [ [ "," ] redirhost-list ] 3010routehost-list = routehost [ [ "," ] routehost-list ] 3011 3012port = "port" ( unary-op | binary-op | "{" op-list "}" ) 3013portspec = "port" ( number | name ) [ ":" ( "*" | number | name ) ] 3014os = "os" ( os-name | "{" os-list "}" ) 3015user = "user" ( unary-op | binary-op | "{" op-list "}" ) 3016group = "group" ( unary-op | binary-op | "{" op-list "}" ) 3017 3018unary-op = [ "=" | "!=" | "\*(Lt" | "\*(Le" | "\*(Gt" | "\*(Ge" ] 3019 ( name | number ) 3020binary-op = number ( "\*(Lt\*(Gt" | "\*(Gt\*(Lt" | ":" ) number 3021op-list = ( unary-op | binary-op ) [ [ "," ] op-list ] 3022 3023os-name = operating-system-name 3024os-list = os-name [ [ "," ] os-list ] 3025 3026flags = "flags" ( [ flag-set ] "/" flag-set | "any" ) 3027flag-set = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ] 3028 [ "W" ] 3029 3030icmp-type = "icmp-type" ( icmp-type-code | "{" icmp-list "}" ) 3031icmp6-type = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" ) 3032icmp-type-code = ( icmp-type-name | icmp-type-number ) 3033 [ "code" ( icmp-code-name | icmp-code-number ) ] 3034icmp-list = icmp-type-code [ [ "," ] icmp-list ] 3035 3036tos = ( "lowdelay" | "throughput" | "reliability" | 3037 [ "0x" ] number ) 3038 3039state-opts = state-opt [ [ "," ] state-opts ] 3040state-opt = ( "max" number | "no-sync" | timeout | "sloppy" | 3041 "source-track" [ ( "rule" | "global" ) ] | 3042 "max-src-nodes" number | "max-src-states" number | 3043 "max-src-conn" number | 3044 "max-src-conn-rate" number "/" number | 3045 "overload" "\*(Lt" string "\*(Gt" [ "flush" ] | 3046 "if-bound" | "floating" ) 3047 3048fragmentation = [ "fragment reassemble" ] 3049 3050timeout-list = timeout [ [ "," ] timeout-list ] 3051timeout = ( "tcp.first" | "tcp.opening" | "tcp.established" | 3052 "tcp.closing" | "tcp.finwait" | "tcp.closed" | 3053 "udp.first" | "udp.single" | "udp.multiple" | 3054 "icmp.first" | "icmp.error" | 3055 "other.first" | "other.single" | "other.multiple" | 3056 "frag" | "interval" | "src.track" | 3057 "adaptive.start" | "adaptive.end" ) number 3058 3059limit-list = limit-item [ [ "," ] limit-list ] 3060limit-item = ( "states" | "frags" | "src-nodes" ) number 3061 3062pooltype = ( "bitmask" | "random" | 3063 "source-hash" [ ( hex-key | string-key ) ] | 3064 "round-robin" ) [ sticky-address ] 3065 3066subqueue = string | "{" queue-list "}" 3067queue-list = string [ [ "," ] string ] 3068cbq-def = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ] 3069priq-def = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ] 3070hfsc-def = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ] 3071cbq-opt = ( "default" | "borrow" | "red" | "ecn" | "rio" ) 3072priq-opt = ( "default" | "red" | "ecn" | "rio" ) 3073hfsc-opt = ( "default" | "red" | "ecn" | "rio" | 3074 linkshare-sc | realtime-sc | upperlimit-sc ) 3075linkshare-sc = "linkshare" sc-spec 3076realtime-sc = "realtime" sc-spec 3077upperlimit-sc = "upperlimit" sc-spec 3078sc-spec = ( bandwidth-spec | 3079 "(" bandwidth-spec number bandwidth-spec ")" ) 3080include = "include" filename 3081.Ed 3082.Sh FILES 3083.Bl -tag -width "/etc/protocols" -compact 3084.It Pa /etc/hosts 3085Host name database. 3086.It Pa /etc/pf.conf 3087Default location of the ruleset file. 3088The file has to be created manually as it is not installed with a 3089standard installation. 3090.It Pa /etc/pf.os 3091Default location of OS fingerprints. 3092.It Pa /etc/protocols 3093Protocol name database. 3094.It Pa /etc/services 3095Service name database. 3096.El 3097.Sh SEE ALSO 3098.Xr altq 4 , 3099.Xr carp 4 , 3100.Xr icmp 4 , 3101.Xr icmp6 4 , 3102.Xr ip 4 , 3103.Xr ip6 4 , 3104.Xr pf 4 , 3105.Xr pfsync 4 , 3106.Xr tcp 4 , 3107.Xr udp 4 , 3108.Xr hosts 5 , 3109.Xr pf.os 5 , 3110.Xr protocols 5 , 3111.Xr services 5 , 3112.Xr ftp-proxy 8 , 3113.Xr pfctl 8 , 3114.Xr pflogd 8 3115.Sh HISTORY 3116The 3117.Nm 3118file format first appeared in 3119.Ox 3.0 . 3120