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 December 7, 2019 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.El 622.Sh TRAFFIC NORMALIZATION 623Traffic normalization is used to sanitize packet content in such 624a way that there are no ambiguities in packet interpretation on 625the receiving side. 626The normalizer does IP fragment reassembly to prevent attacks 627that confuse intrusion detection systems by sending overlapping 628IP fragments. 629Packet normalization is invoked with the 630.Ar scrub 631directive. 632.Pp 633.Ar scrub 634has the following options: 635.Bl -tag -width xxxx 636.It Ar no-df 637Clears the 638.Ar dont-fragment 639bit from a matching IP packet. 640Some operating systems are known to generate fragmented packets with the 641.Ar dont-fragment 642bit set. 643This is particularly true with NFS. 644.Ar Scrub 645will drop such fragmented 646.Ar dont-fragment 647packets unless 648.Ar no-df 649is specified. 650.Pp 651Unfortunately some operating systems also generate their 652.Ar dont-fragment 653packets with a zero IP identification field. 654Clearing the 655.Ar dont-fragment 656bit on packets with a zero IP ID may cause deleterious results if an 657upstream router later fragments the packet. 658Using the 659.Ar random-id 660modifier (see below) is recommended in combination with the 661.Ar no-df 662modifier to ensure unique IP identifiers. 663.It Ar min-ttl Aq Ar number 664Enforces a minimum TTL for matching IP packets. 665.It Ar max-mss Aq Ar number 666Enforces a maximum MSS for matching TCP packets. 667.It Xo Ar set-tos Aq Ar string 668.No \*(Ba Aq Ar number 669.Xc 670Enforces a 671.Em TOS 672for matching IP packets. 673.Em TOS 674may be 675given as one of 676.Ar critical , 677.Ar inetcontrol , 678.Ar lowdelay , 679.Ar netcontrol , 680.Ar throughput , 681.Ar reliability , 682or one of the DiffServ Code Points: 683.Ar ef , 684.Ar va , 685.Ar af11 No ... Ar af43 , 686.Ar cs0 No ... Ar cs7 ; 687or as either hex or decimal. 688.It Ar random-id 689Replaces the IP identification field with random values to compensate 690for predictable values generated by many hosts. 691This option only applies to packets that are not fragmented 692after the optional fragment reassembly. 693.It Ar fragment reassemble 694Using 695.Ar scrub 696rules, fragments can be reassembled by normalization. 697In this case, fragments are buffered until they form a complete 698packet, and only the completed packet is passed on to the filter. 699The advantage is that filter rules have to deal only with complete 700packets, and can ignore fragments. 701The drawback of caching fragments is the additional memory cost. 702.It Ar reassemble tcp 703Statefully normalizes TCP connections. 704.Ar scrub reassemble tcp 705rules may not have the direction (in/out) specified. 706.Ar reassemble tcp 707performs the following normalizations: 708.Pp 709.Bl -tag -width timeout -compact 710.It ttl 711Neither side of the connection is allowed to reduce their IP TTL. 712An attacker may send a packet such that it reaches the firewall, affects 713the firewall state, and expires before reaching the destination host. 714.Ar reassemble tcp 715will raise the TTL of all packets back up to the highest value seen on 716the connection. 717.It timestamp modulation 718Modern TCP stacks will send a timestamp on every TCP packet and echo 719the other endpoint's timestamp back to them. 720Many operating systems will merely start the timestamp at zero when 721first booted, and increment it several times a second. 722The uptime of the host can be deduced by reading the timestamp and multiplying 723by a constant. 724Also observing several different timestamps can be used to count hosts 725behind a NAT device. 726And spoofing TCP packets into a connection requires knowing or guessing 727valid timestamps. 728Timestamps merely need to be monotonically increasing and not derived off a 729guessable base time. 730.Ar reassemble tcp 731will cause 732.Ar scrub 733to modulate the TCP timestamps with a random number. 734.It extended PAWS checks 735There is a problem with TCP on long fat pipes, in that a packet might get 736delayed for longer than it takes the connection to wrap its 32-bit sequence 737space. 738In such an occurrence, the old packet would be indistinguishable from a 739new packet and would be accepted as such. 740The solution to this is called PAWS: Protection Against Wrapped Sequence 741numbers. 742It protects against it by making sure the timestamp on each packet does 743not go backwards. 744.Ar reassemble tcp 745also makes sure the timestamp on the packet does not go forward more 746than the RFC allows. 747By doing this, 748.Xr pf 4 749artificially extends the security of TCP sequence numbers by 10 to 18 750bits when the host uses appropriately randomized timestamps, since a 751blind attacker would have to guess the timestamp as well. 752.El 753.El 754.Pp 755For example, 756.Bd -literal -offset indent 757scrub in on $ext_if all fragment reassemble 758.Ed 759.Pp 760The 761.Ar no 762option prefixed to a scrub rule causes matching packets to remain unscrubbed, 763much in the same way as 764.Ar drop quick 765works in the packet filter (see below). 766This mechanism should be used when it is necessary to exclude specific packets 767from broader scrub rules. 768.Sh QUEUEING 769The ALTQ system is currently not available in the GENERIC kernel nor as 770loadable modules. 771In order to use the herein after called queueing options one has to use a 772custom built kernel. 773Please refer to 774.Xr altq 4 775to learn about the related kernel options. 776.Pp 777Packets can be assigned to queues for the purpose of bandwidth 778control. 779At least two declarations are required to configure queues, and later 780any packet filtering rule can reference the defined queues by name. 781During the filtering component of 782.Nm pf.conf , 783the last referenced 784.Ar queue 785name is where any packets from 786.Ar pass 787rules will be queued, while for 788.Ar block 789rules it specifies where any resulting ICMP or TCP RST 790packets should be queued. 791The 792.Ar scheduler 793defines the algorithm used to decide which packets get delayed, dropped, or 794sent out immediately. 795There are three 796.Ar schedulers 797currently supported. 798.Bl -tag -width xxxx 799.It Ar cbq 800Class Based Queueing. 801.Ar Queues 802attached to an interface build a tree, thus each 803.Ar queue 804can have further child 805.Ar queues . 806Each queue can have a 807.Ar priority 808and a 809.Ar bandwidth 810assigned. 811.Ar Priority 812mainly controls the time packets take to get sent out, while 813.Ar bandwidth 814has primarily effects on throughput. 815.Ar cbq 816achieves both partitioning and sharing of link bandwidth 817by hierarchically structured classes. 818Each class has its own 819.Ar queue 820and is assigned its share of 821.Ar bandwidth . 822A child class can borrow bandwidth from its parent class 823as long as excess bandwidth is available 824(see the option 825.Ar borrow , 826below). 827.It Ar priq 828Priority Queueing. 829.Ar Queues 830are flat attached to the interface, thus, 831.Ar queues 832cannot have further child 833.Ar queues . 834Each 835.Ar queue 836has a unique 837.Ar priority 838assigned, ranging from 0 to 15. 839Packets in the 840.Ar queue 841with the highest 842.Ar priority 843are processed first. 844.It Ar hfsc 845Hierarchical Fair Service Curve. 846.Ar Queues 847attached to an interface build a tree, thus each 848.Ar queue 849can have further child 850.Ar queues . 851Each queue can have a 852.Ar priority 853and a 854.Ar bandwidth 855assigned. 856.Ar Priority 857mainly controls the time packets take to get sent out, while 858.Ar bandwidth 859primarily affects throughput. 860.Ar hfsc 861supports both link-sharing and guaranteed real-time services. 862It employs a service curve based QoS model, 863and its unique feature is an ability to decouple 864.Ar delay 865and 866.Ar bandwidth 867allocation. 868.El 869.Pp 870The interfaces on which queueing should be activated are declared using 871the 872.Ar altq on 873declaration. 874.Ar altq on 875has the following keywords: 876.Bl -tag -width xxxx 877.It Aq Ar interface 878Queueing is enabled on the named interface. 879.It Aq Ar scheduler 880Specifies which queueing scheduler to use. 881Currently supported values 882are 883.Ar cbq 884for Class Based Queueing, 885.Ar priq 886for Priority Queueing and 887.Ar hfsc 888for the Hierarchical Fair Service Curve scheduler. 889.It Ar bandwidth Aq Ar bw 890The maximum bitrate for all queues on an 891interface may be specified using the 892.Ar bandwidth 893keyword. 894The value can be specified as an absolute value or as a 895percentage of the interface bandwidth. 896When using an absolute value, the suffixes 897.Ar b , 898.Ar Kb , 899.Ar Mb , 900and 901.Ar Gb 902are used to represent bits, kilobits, megabits, and 903gigabits per second, respectively. 904The value must not exceed the interface bandwidth. 905If 906.Ar bandwidth 907is not specified, the interface bandwidth is used 908(but take note that some interfaces do not know their bandwidth, 909or can adapt their bandwidth rates). 910.It Ar qlimit Aq Ar limit 911The maximum number of packets held in the queue. 912The default is 50. 913.It Ar tbrsize Aq Ar size 914Adjusts the size, in bytes, of the token bucket regulator. 915If not specified, heuristics based on the 916interface bandwidth are used to determine the size. 917.It Ar queue Aq Ar list 918Defines a list of subqueues to create on an interface. 919.El 920.Pp 921In the following example, the interface dc0 922should queue up to 5Mbps in four second-level queues using 923Class Based Queueing. 924Those four queues will be shown in a later example. 925.Bd -literal -offset indent 926altq on dc0 cbq bandwidth 5Mb queue { std, http, mail, ssh } 927.Ed 928.Pp 929Once interfaces are activated for queueing using the 930.Ar altq 931directive, a sequence of 932.Ar queue 933directives may be defined. 934The name associated with a 935.Ar queue 936must match a queue defined in the 937.Ar altq 938directive (e.g. mail), or, except for the 939.Ar priq 940.Ar scheduler , 941in a parent 942.Ar queue 943declaration. 944The following keywords can be used: 945.Bl -tag -width xxxx 946.It Ar on Aq Ar interface 947Specifies the interface the queue operates on. 948If not given, it operates on all matching interfaces. 949.It Ar bandwidth Aq Ar bw 950Specifies the maximum bitrate to be processed by the queue. 951This value must not exceed the value of the parent 952.Ar queue 953and can be specified as an absolute value or a percentage of the parent 954queue's bandwidth. 955If not specified, defaults to 100% of the parent queue's bandwidth. 956The 957.Ar priq 958scheduler does not support bandwidth specification. 959.It Ar priority Aq Ar level 960Between queues a priority level can be set. 961For 962.Ar cbq 963and 964.Ar hfsc , 965the range is 0 to 7 and for 966.Ar priq , 967the range is 0 to 15. 968The default for all is 1. 969.Ar Priq 970queues with a higher priority are always served first. 971.Ar Cbq 972and 973.Ar Hfsc 974queues with a higher priority are preferred in the case of overload. 975.It Ar qlimit Aq Ar limit 976The maximum number of packets held in the queue. 977The default is 50. 978.El 979.Pp 980The 981.Ar scheduler 982can get additional parameters with 983.Xo Aq Ar scheduler 984.Pf ( Aq Ar parameters ) . 985.Xc 986Parameters are as follows: 987.Bl -tag -width Fl 988.It Ar default 989Packets not matched by another queue are assigned to this one. 990Exactly one default queue is required. 991.It Ar red 992Enable RED (Random Early Detection) on this queue. 993RED drops packets with a probability proportional to the average 994queue length. 995.It Ar rio 996Enables RIO on this queue. 997RIO is RED with IN/OUT, thus running 998RED two times more than RIO would achieve the same effect. 999RIO is currently not supported in the GENERIC kernel. 1000.It Ar ecn 1001Enables ECN (Explicit Congestion Notification) on this queue. 1002ECN implies RED. 1003.El 1004.Pp 1005The 1006.Ar cbq 1007.Ar scheduler 1008supports an additional option: 1009.Bl -tag -width Fl 1010.It Ar borrow 1011The queue can borrow bandwidth from the parent. 1012.El 1013.Pp 1014The 1015.Ar hfsc 1016.Ar scheduler 1017supports some additional options: 1018.Bl -tag -width Fl 1019.It Ar realtime Aq Ar sc 1020The minimum required bandwidth for the queue. 1021.It Ar upperlimit Aq Ar sc 1022The maximum allowed bandwidth for the queue. 1023.It Ar linkshare Aq Ar sc 1024The bandwidth share of a backlogged queue. 1025.El 1026.Pp 1027.Aq Ar sc 1028is an acronym for 1029.Ar service curve . 1030.Pp 1031The format for service curve specifications is 1032.Ar ( m1 , d , m2 ) . 1033.Ar m2 1034controls the bandwidth assigned to the queue. 1035.Ar m1 1036and 1037.Ar d 1038are optional and can be used to control the initial bandwidth assignment. 1039For the first 1040.Ar d 1041milliseconds the queue gets the bandwidth given as 1042.Ar m1 , 1043afterwards the value given in 1044.Ar m2 . 1045.Pp 1046Furthermore, with 1047.Ar cbq 1048and 1049.Ar hfsc , 1050child queues can be specified as in an 1051.Ar altq 1052declaration, thus building a tree of queues using a part of 1053their parent's bandwidth. 1054.Pp 1055Packets can be assigned to queues based on filter rules by using the 1056.Ar queue 1057keyword. 1058Normally only one 1059.Ar queue 1060is specified; when a second one is specified it will instead be used for 1061packets which have a 1062.Em TOS 1063of 1064.Em lowdelay 1065and for TCP ACKs with no data payload. 1066.Pp 1067To continue the previous example, the examples below would specify the 1068four referenced 1069queues, plus a few child queues. 1070Interactive 1071.Xr ssh 1 1072sessions get priority over bulk transfers like 1073.Xr scp 1 1074and 1075.Xr sftp 1 . 1076The queues may then be referenced by filtering rules (see 1077.Sx PACKET FILTERING 1078below). 1079.Bd -literal 1080queue std bandwidth 10% cbq(default) 1081queue http bandwidth 60% priority 2 cbq(borrow red) \e 1082 { employees, developers } 1083queue developers bandwidth 75% cbq(borrow) 1084queue employees bandwidth 15% 1085queue mail bandwidth 10% priority 0 cbq(borrow ecn) 1086queue ssh bandwidth 20% cbq(borrow) { ssh_interactive, ssh_bulk } 1087queue ssh_interactive bandwidth 50% priority 7 cbq(borrow) 1088queue ssh_bulk bandwidth 50% priority 0 cbq(borrow) 1089 1090block return out on dc0 inet all queue std 1091pass out on dc0 inet proto tcp from $developerhosts to any port 80 \e 1092 queue developers 1093pass out on dc0 inet proto tcp from $employeehosts to any port 80 \e 1094 queue employees 1095pass out on dc0 inet proto tcp from any to any port 22 \e 1096 queue(ssh_bulk, ssh_interactive) 1097pass out on dc0 inet proto tcp from any to any port 25 \e 1098 queue mail 1099.Ed 1100.Sh TRANSLATION 1101Translation rules modify either the source or destination address of the 1102packets associated with a stateful connection. 1103A stateful connection is automatically created to track packets matching 1104such a rule as long as they are not blocked by the filtering section of 1105.Nm pf.conf . 1106The translation engine modifies the specified address and/or port in the 1107packet, recalculates IP, TCP and UDP checksums as necessary, and passes it to 1108the packet filter for evaluation. 1109.Pp 1110Since translation occurs before filtering the filter 1111engine will see packets as they look after any 1112addresses and ports have been translated. 1113Filter rules will therefore have to filter based on the translated 1114address and port number. 1115Packets that match a translation rule are only automatically passed if 1116the 1117.Ar pass 1118modifier is given, otherwise they are 1119still subject to 1120.Ar block 1121and 1122.Ar pass 1123rules. 1124.Pp 1125The state entry created permits 1126.Xr pf 4 1127to keep track of the original address for traffic associated with that state 1128and correctly direct return traffic for that connection. 1129.Pp 1130Various types of translation are possible with pf: 1131.Bl -tag -width xxxx 1132.It Ar binat 1133A 1134.Ar binat 1135rule specifies a bidirectional mapping between an external IP netblock 1136and an internal IP netblock. 1137.It Ar nat 1138A 1139.Ar nat 1140rule specifies that IP addresses are to be changed as the packet 1141traverses the given interface. 1142This technique allows one or more IP addresses 1143on the translating host to support network traffic for a larger range of 1144machines on an "inside" network. 1145Although in theory any IP address can be used on the inside, it is strongly 1146recommended that one of the address ranges defined by RFC 1918 be used. 1147These netblocks are: 1148.Bd -literal 114910.0.0.0 - 10.255.255.255 (all of net 10, i.e., 10/8) 1150172.16.0.0 - 172.31.255.255 (i.e., 172.16/12) 1151192.168.0.0 - 192.168.255.255 (i.e., 192.168/16) 1152.Ed 1153.It Pa rdr 1154The packet is redirected to another destination and possibly a 1155different port. 1156.Ar rdr 1157rules can optionally specify port ranges instead of single ports. 1158rdr ... port 2000:2999 -\*(Gt ... port 4000 1159redirects ports 2000 to 2999 (inclusive) to port 4000. 1160rdr ... port 2000:2999 -\*(Gt ... port 4000:* 1161redirects port 2000 to 4000, 2001 to 4001, ..., 2999 to 4999. 1162.El 1163.Pp 1164In addition to modifying the address, some translation rules may modify 1165source or destination ports for 1166.Xr tcp 4 1167or 1168.Xr udp 4 1169connections; implicitly in the case of 1170.Ar nat 1171rules and explicitly in the case of 1172.Ar rdr 1173rules. 1174Port numbers are never translated with a 1175.Ar binat 1176rule. 1177.Pp 1178Evaluation order of the translation rules is dependent on the type 1179of the translation rules and of the direction of a packet. 1180.Ar binat 1181rules are always evaluated first. 1182Then either the 1183.Ar rdr 1184rules are evaluated on an inbound packet or the 1185.Ar nat 1186rules on an outbound packet. 1187Rules of the same type are evaluated in the same order in which they 1188appear in the ruleset. 1189The first matching rule decides what action is taken. 1190.Pp 1191The 1192.Ar no 1193option prefixed to a translation rule causes packets to remain untranslated, 1194much in the same way as 1195.Ar drop quick 1196works in the packet filter (see below). 1197If no rule matches the packet it is passed to the filter engine unmodified. 1198.Pp 1199Translation rules apply only to packets that pass through 1200the specified interface, and if no interface is specified, 1201translation is applied to packets on all interfaces. 1202For instance, redirecting port 80 on an external interface to an internal 1203web server will only work for connections originating from the outside. 1204Connections to the address of the external interface from local hosts will 1205not be redirected, since such packets do not actually pass through the 1206external interface. 1207Redirections cannot reflect packets back through the interface they arrive 1208on, they can only be redirected to hosts connected to different interfaces 1209or to the firewall itself. 1210.Pp 1211Note that redirecting external incoming connections to the loopback 1212address, as in 1213.Bd -literal -offset indent 1214rdr on ne3 inet proto tcp to port smtp -\*(Gt 127.0.0.1 port spamd 1215.Ed 1216.Pp 1217will effectively allow an external host to connect to daemons 1218bound solely to the loopback address, circumventing the traditional 1219blocking of such connections on a real interface. 1220Unless this effect is desired, any of the local non-loopback addresses 1221should be used as redirection target instead, which allows external 1222connections only to daemons bound to this address or not bound to 1223any address. 1224.Pp 1225See 1226.Sx TRANSLATION EXAMPLES 1227below. 1228.Sh PACKET FILTERING 1229.Xr pf 4 1230has the ability to 1231.Ar block 1232and 1233.Ar pass 1234packets based on attributes of their layer 3 (see 1235.Xr ip 4 1236and 1237.Xr ip6 4 ) 1238and layer 4 (see 1239.Xr icmp 4 , 1240.Xr icmp6 4 , 1241.Xr tcp 4 , 1242.Xr udp 4 ) 1243headers. 1244In addition, packets may also be 1245assigned to queues for the purpose of bandwidth control. 1246.Pp 1247For each packet processed by the packet filter, the filter rules are 1248evaluated in sequential order, from first to last. 1249The last matching rule decides what action is taken. 1250If no rule matches the packet, the default action is to pass 1251the packet. 1252.Pp 1253The following actions can be used in the filter: 1254.Bl -tag -width xxxx 1255.It Ar block 1256The packet is blocked. 1257There are a number of ways in which a 1258.Ar block 1259rule can behave when blocking a packet. 1260The default behaviour is to 1261.Ar drop 1262packets silently, however this can be overridden or made 1263explicit either globally, by setting the 1264.Ar block-policy 1265option, or on a per-rule basis with one of the following options: 1266.Pp 1267.Bl -tag -width xxxx -compact 1268.It Ar drop 1269The packet is silently dropped. 1270.It Ar return-rst 1271This applies only to 1272.Xr tcp 4 1273packets, and issues a TCP RST which closes the 1274connection. 1275.It Ar return-icmp 1276.It Ar return-icmp6 1277This causes ICMP messages to be returned for packets which match the rule. 1278By default this is an ICMP UNREACHABLE message, however this 1279can be overridden by specifying a message as a code or number. 1280.It Ar return 1281This causes a TCP RST to be returned for 1282.Xr tcp 4 1283packets and an ICMP UNREACHABLE for UDP and other packets. 1284.El 1285.Pp 1286Options returning ICMP packets currently have no effect if 1287.Xr pf 4 1288operates on a 1289.Xr if_bridge 4 , 1290as the code to support this feature has not yet been implemented. 1291.Pp 1292The simplest mechanism to block everything by default and only pass 1293packets that match explicit rules is specify a first filter rule of: 1294.Bd -literal -offset indent 1295block all 1296.Ed 1297.It Ar pass 1298The packet is passed; 1299state is created unless the 1300.Ar no state 1301option is specified. 1302.El 1303.Pp 1304By default 1305.Xr pf 4 1306filters packets statefully; the first time a packet matches a 1307.Ar pass 1308rule, a state entry is created; for subsequent packets the filter checks 1309whether the packet matches any state. 1310If it does, the packet is passed without evaluation of any rules. 1311After the connection is closed or times out, the state entry is automatically 1312removed. 1313.Pp 1314This has several advantages. 1315For TCP connections, comparing a packet to a state involves checking 1316its sequence numbers, as well as TCP timestamps if a 1317.Ar scrub reassemble tcp 1318rule applies to the connection. 1319If these values are outside the narrow windows of expected 1320values, the packet is dropped. 1321This prevents spoofing attacks, such as when an attacker sends packets with 1322a fake source address/port but does not know the connection's sequence 1323numbers. 1324Similarly, 1325.Xr pf 4 1326knows how to match ICMP replies to states. 1327For example, 1328.Bd -literal -offset indent 1329pass out inet proto icmp all icmp-type echoreq 1330.Ed 1331.Pp 1332allows echo requests (such as those created by 1333.Xr ping 8 ) 1334out statefully, and matches incoming echo replies correctly to states. 1335.Pp 1336Also, looking up states is usually faster than evaluating rules. 1337If there are 50 rules, all of them are evaluated sequentially in O(n). 1338Even with 50000 states, only 16 comparisons are needed to match a 1339state, since states are stored in a binary search tree that allows 1340searches in O(log2 n). 1341.Pp 1342Furthermore, correct handling of ICMP error messages is critical to 1343many protocols, particularly TCP. 1344.Xr pf 4 1345matches ICMP error messages to the correct connection, checks them against 1346connection parameters, and passes them if appropriate. 1347For example if an ICMP source quench message referring to a stateful TCP 1348connection arrives, it will be matched to the state and get passed. 1349.Pp 1350Finally, state tracking is required for 1351.Ar nat , binat No and Ar rdr 1352rules, in order to track address and port translations and reverse the 1353translation on returning packets. 1354.Pp 1355.Xr pf 4 1356will also create state for other protocols which are effectively stateless by 1357nature. 1358UDP packets are matched to states using only host addresses and ports, 1359and other protocols are matched to states using only the host addresses. 1360.Pp 1361If stateless filtering of individual packets is desired, 1362the 1363.Ar no state 1364keyword can be used to specify that state will not be created 1365if this is the last matching rule. 1366A number of parameters can also be set to affect how 1367.Xr pf 4 1368handles state tracking. 1369See 1370.Sx STATEFUL TRACKING OPTIONS 1371below for further details. 1372.Sh PARAMETERS 1373The rule parameters specify the packets to which a rule applies. 1374A packet always comes in on, or goes out through, one interface. 1375Most parameters are optional. 1376If a parameter is specified, the rule only applies to packets with 1377matching attributes. 1378Certain parameters can be expressed as lists, in which case 1379.Xr pfctl 8 1380generates all needed rule combinations. 1381.Bl -tag -width xxxx 1382.It Ar in No or Ar out 1383This rule applies to incoming or outgoing packets. 1384If neither 1385.Ar in 1386nor 1387.Ar out 1388are specified, the rule will match packets in both directions. 1389.It Ar log 1390In addition to the action specified, a log message is generated. 1391Only the packet that establishes the state is logged, 1392unless the 1393.Ar no state 1394option is specified. 1395The logged packets are sent to a 1396.Xr pflog 4 1397interface, by default 1398.Ar pflog0 . 1399This interface is monitored by the 1400.Xr pflogd 8 1401logging daemon, which dumps the logged packets to the file 1402.Pa /var/log/pflog 1403in 1404.Xr pcap 3 1405binary format. 1406.It Ar log (all) 1407Used to force logging of all packets for a connection. 1408This is not necessary when 1409.Ar no state 1410is explicitly specified. 1411As with 1412.Ar log , 1413packets are logged to 1414.Xr pflog 4 . 1415.It Ar log (user) 1416Logs the 1417.Ux 1418user ID of the user that owns the socket and the PID of the process that 1419has the socket open where the packet is sourced from or destined to 1420(depending on which socket is local). 1421This is in addition to the normal information logged. 1422.Pp 1423Only the first packet 1424logged via 1425.Ar log (all, user) 1426will have the user credentials logged when using stateful matching. 1427.It Ar log (to Aq Ar interface ) 1428Send logs to the specified 1429.Xr pflog 4 1430interface instead of 1431.Ar pflog0 . 1432.It Ar quick 1433If a packet matches a rule which has the 1434.Ar quick 1435option set, this rule 1436is considered the last matching rule, and evaluation of subsequent rules 1437is skipped. 1438.It Ar on Aq Ar interface 1439This rule applies only to packets coming in on, or going out through, this 1440particular interface or interface group. 1441For more information on interface groups, 1442see the 1443.Ic group 1444keyword in 1445.Xr ifconfig 8 . 1446.It Aq Ar af 1447This rule applies only to packets of this address family. 1448Supported values are 1449.Ar inet 1450and 1451.Ar inet6 . 1452.It Ar proto Aq Ar protocol 1453This rule applies only to packets of this protocol. 1454Common protocols are 1455.Xr icmp 4 , 1456.Xr icmp6 4 , 1457.Xr tcp 4 , 1458and 1459.Xr udp 4 . 1460For a list of all the protocol name to number mappings used by 1461.Xr pfctl 8 , 1462see the file 1463.Pa /etc/protocols . 1464.It Xo 1465.Ar from Aq Ar source 1466.Ar port Aq Ar source 1467.Ar os Aq Ar source 1468.Ar to Aq Ar dest 1469.Ar port Aq Ar dest 1470.Xc 1471This rule applies only to packets with the specified source and destination 1472addresses and ports. 1473.Pp 1474Addresses can be specified in CIDR notation (matching netblocks), as 1475symbolic host names, interface names or interface group names, or as any 1476of the following keywords: 1477.Pp 1478.Bl -tag -width xxxxxxxxxxxxxx -compact 1479.It Ar any 1480Any address. 1481.It Ar no-route 1482Any address which is not currently routable. 1483.It Ar urpf-failed 1484Any source address that fails a unicast reverse path forwarding (URPF) 1485check, i.e. packets coming in on an interface other than that which holds 1486the route back to the packet's source address. 1487.It Aq Ar table 1488Any address that matches the given table. 1489.El 1490.Pp 1491Ranges of addresses are specified by using the 1492.Sq - 1493operator. 1494For instance: 1495.Dq 10.1.1.10 - 10.1.1.12 1496means all addresses from 10.1.1.10 to 10.1.1.12, 1497hence addresses 10.1.1.10, 10.1.1.11, and 10.1.1.12. 1498.Pp 1499Interface names and interface group names can have modifiers appended: 1500.Pp 1501.Bl -tag -width xxxxxxxxxxxx -compact 1502.It Ar :network 1503Translates to the network(s) attached to the interface. 1504.It Ar :broadcast 1505Translates to the interface's broadcast address(es). 1506.It Ar :peer 1507Translates to the point-to-point interface's peer address(es). 1508.It Ar :0 1509Do not include interface aliases. 1510.El 1511.Pp 1512Host names may also have the 1513.Ar :0 1514option appended to restrict the name resolution to the first of each 1515v4 and non-link-local v6 address found. 1516.Pp 1517Host name resolution and interface to address translation are done at 1518ruleset load-time. 1519When the address of an interface (or host name) changes (under DHCP or PPP, 1520for instance), the ruleset must be reloaded for the change to be reflected 1521in the kernel. 1522Surrounding the interface name (and optional modifiers) in parentheses 1523changes this behaviour. 1524When the interface name is surrounded by parentheses, the rule is 1525automatically updated whenever the interface changes its address. 1526The ruleset does not need to be reloaded. 1527This is especially useful with 1528.Ar nat . 1529.Pp 1530Ports can be specified either by number or by name. 1531For example, port 80 can be specified as 1532.Em www . 1533For a list of all port name to number mappings used by 1534.Xr pfctl 8 , 1535see the file 1536.Pa /etc/services . 1537.Pp 1538Ports and ranges of ports are specified by using these operators: 1539.Bd -literal -offset indent 1540= (equal) 1541!= (unequal) 1542\*(Lt (less than) 1543\*(Le (less than or equal) 1544\*(Gt (greater than) 1545\*(Ge (greater than or equal) 1546: (range including boundaries) 1547\*(Gt\*(Lt (range excluding boundaries) 1548\*(Lt\*(Gt (except range) 1549.Ed 1550.Pp 1551.Sq \*(Gt\*(Lt , 1552.Sq \*(Lt\*(Gt 1553and 1554.Sq \&: 1555are binary operators (they take two arguments). 1556For instance: 1557.Bl -tag -width Fl 1558.It Ar port 2000:2004 1559means 1560.Sq all ports \*(Ge 2000 and \*(Le 2004 , 1561hence ports 2000, 2001, 2002, 2003 and 2004. 1562.It Ar port 2000 \*(Gt\*(Lt 2004 1563means 1564.Sq all ports \*(Gt 2000 and \*(Lt 2004 , 1565hence ports 2001, 2002 and 2003. 1566.It Ar port 2000 \*(Lt\*(Gt 2004 1567means 1568.Sq all ports \*(Lt 2000 or \*(Gt 2004 , 1569hence ports 1-1999 and 2005-65535. 1570.El 1571.Pp 1572The operating system of the source host can be specified in the case of TCP 1573rules with the 1574.Ar OS 1575modifier. 1576See the 1577.Sx OPERATING SYSTEM FINGERPRINTING 1578section for more information. 1579.Pp 1580The host, port and OS specifications are optional, as in the following examples: 1581.Bd -literal -offset indent 1582pass in all 1583pass in from any to any 1584pass in proto tcp from any port \*(Le 1024 to any 1585pass in proto tcp from any to any port 25 1586pass in proto tcp from 10.0.0.0/8 port \*(Gt 1024 \e 1587 to ! 10.1.2.3 port != ssh 1588pass in proto tcp from any os "OpenBSD" 1589.Ed 1590.It Ar all 1591This is equivalent to "from any to any". 1592.It Ar group Aq Ar group 1593Similar to 1594.Ar user , 1595this rule only applies to packets of sockets owned by the specified group. 1596.It Ar user Aq Ar user 1597This rule only applies to packets of sockets owned by the specified user. 1598For outgoing connections initiated from the firewall, this is the user 1599that opened the connection. 1600For incoming connections to the firewall itself, this is the user that 1601listens on the destination port. 1602For forwarded connections, where the firewall is not a connection endpoint, 1603the user and group are 1604.Em unknown . 1605.Pp 1606All packets, both outgoing and incoming, of one connection are associated 1607with the same user and group. 1608Only TCP and UDP packets can be associated with users; for other protocols 1609these parameters are ignored. 1610.Pp 1611User and group refer to the effective (as opposed to the real) IDs, in 1612case the socket is created by a setuid/setgid process. 1613User and group IDs are stored when a socket is created; 1614when a process creates a listening socket as root (for instance, by 1615binding to a privileged port) and subsequently changes to another 1616user ID (to drop privileges), the credentials will remain root. 1617.Pp 1618User and group IDs can be specified as either numbers or names. 1619The syntax is similar to the one for ports. 1620The value 1621.Em unknown 1622matches packets of forwarded connections. 1623.Em unknown 1624can only be used with the operators 1625.Cm = 1626and 1627.Cm != . 1628Other constructs like 1629.Cm user \*(Ge unknown 1630are invalid. 1631Forwarded packets with unknown user and group ID match only rules 1632that explicitly compare against 1633.Em unknown 1634with the operators 1635.Cm = 1636or 1637.Cm != . 1638For instance 1639.Cm user \*(Ge 0 1640does not match forwarded packets. 1641The following example allows only selected users to open outgoing 1642connections: 1643.Bd -literal -offset indent 1644block out proto { tcp, udp } all 1645pass out proto { tcp, udp } all user { \*(Lt 1000, dhartmei } 1646.Ed 1647.It Xo Ar flags Aq Ar a 1648.Pf / Ns Aq Ar b 1649.No \*(Ba / Ns Aq Ar b 1650.No \*(Ba any 1651.Xc 1652This rule only applies to TCP packets that have the flags 1653.Aq Ar a 1654set out of set 1655.Aq Ar b . 1656Flags not specified in 1657.Aq Ar b 1658are ignored. 1659For stateful connections, the default is 1660.Ar flags S/SA . 1661To indicate that flags should not be checked at all, specify 1662.Ar flags any . 1663The flags are: (F)IN, (S)YN, (R)ST, (P)USH, (A)CK, (U)RG, (E)CE, and C(W)R. 1664.Bl -tag -width Fl 1665.It Ar flags S/S 1666Flag SYN is set. 1667The other flags are ignored. 1668.It Ar flags S/SA 1669This is the default setting for stateful connections. 1670Out of SYN and ACK, exactly SYN may be set. 1671SYN, SYN+PSH and SYN+RST match, but SYN+ACK, ACK and ACK+RST do not. 1672This is more restrictive than the previous example. 1673.It Ar flags /SFRA 1674If the first set is not specified, it defaults to none. 1675All of SYN, FIN, RST and ACK must be unset. 1676.El 1677.Pp 1678Because 1679.Ar flags S/SA 1680is applied by default (unless 1681.Ar no state 1682is specified), only the initial SYN packet of a TCP handshake will create 1683a state for a TCP connection. 1684It is possible to be less restrictive, and allow state creation from 1685intermediate 1686.Pq non-SYN 1687packets, by specifying 1688.Ar flags any . 1689This will cause 1690.Xr pf 4 1691to synchronize to existing connections, for instance 1692if one flushes the state table. 1693However, states created from such intermediate packets may be missing 1694connection details such as the TCP window scaling factor. 1695States which modify the packet flow, such as those affected by 1696.Ar nat , binat No or Ar rdr 1697rules, 1698.Ar modulate No or Ar synproxy state 1699options, or scrubbed with 1700.Ar reassemble tcp 1701will also not be recoverable from intermediate packets. 1702Such connections will stall and time out. 1703.It Xo Ar icmp-type Aq Ar type 1704.Ar code Aq Ar code 1705.Xc 1706.It Xo Ar icmp6-type Aq Ar type 1707.Ar code Aq Ar code 1708.Xc 1709This rule only applies to ICMP or ICMPv6 packets with the specified type 1710and code. 1711Text names for ICMP types and codes are listed in 1712.Xr icmp 4 1713and 1714.Xr icmp6 4 . 1715This parameter is only valid for rules that cover protocols ICMP or 1716ICMP6. 1717The protocol and the ICMP type indicator 1718.Po 1719.Ar icmp-type 1720or 1721.Ar icmp6-type 1722.Pc 1723must match. 1724.It Xo Ar tos Aq Ar string 1725.No \*(Ba Aq Ar number 1726.Xc 1727This rule applies to packets with the specified 1728.Em TOS 1729bits set. 1730.Em TOS 1731may be 1732given as one of 1733.Ar critical , 1734.Ar inetcontrol , 1735.Ar lowdelay , 1736.Ar netcontrol , 1737.Ar throughput , 1738.Ar reliability , 1739or one of the DiffServ Code Points: 1740.Ar ef , 1741.Ar va , 1742.Ar af11 No ... Ar af43 , 1743.Ar cs0 No ... Ar cs7 ; 1744or as either hex or decimal. 1745.Pp 1746For example, the following rules are identical: 1747.Bd -literal -offset indent 1748pass all tos lowdelay 1749pass all tos 0x10 1750pass all tos 16 1751.Ed 1752.It Ar allow-opts 1753By default, IPv4 packets with IP options or IPv6 packets with routing 1754extension headers are blocked. 1755When 1756.Ar allow-opts 1757is specified for a 1758.Ar pass 1759rule, packets that pass the filter based on that rule (last matching) 1760do so even if they contain IP options or routing extension headers. 1761For packets that match state, the rule that initially created the 1762state is used. 1763The implicit 1764.Ar pass 1765rule that is used when a packet does not match any rules does not 1766allow IP options. 1767.It Ar label Aq Ar string 1768Adds a label (name) to the rule, which can be used to identify the rule. 1769For instance, 1770pfctl -s labels 1771shows per-rule statistics for rules that have labels. 1772.Pp 1773The following macros can be used in labels: 1774.Pp 1775.Bl -tag -width $srcaddr -compact -offset indent 1776.It Ar $if 1777The interface. 1778.It Ar $srcaddr 1779The source IP address. 1780.It Ar $dstaddr 1781The destination IP address. 1782.It Ar $srcport 1783The source port specification. 1784.It Ar $dstport 1785The destination port specification. 1786.It Ar $proto 1787The protocol name. 1788.It Ar $nr 1789The rule number. 1790.El 1791.Pp 1792For example: 1793.Bd -literal -offset indent 1794ips = \&"{ 1.2.3.4, 1.2.3.5 }\&" 1795pass in proto tcp from any to $ips \e 1796 port \*(Gt 1023 label \&"$dstaddr:$dstport\&" 1797.Ed 1798.Pp 1799expands to 1800.Bd -literal -offset indent 1801pass in inet proto tcp from any to 1.2.3.4 \e 1802 port \*(Gt 1023 label \&"1.2.3.4:\*(Gt1023\&" 1803pass in inet proto tcp from any to 1.2.3.5 \e 1804 port \*(Gt 1023 label \&"1.2.3.5:\*(Gt1023\&" 1805.Ed 1806.Pp 1807The macro expansion for the 1808.Ar label 1809directive occurs only at configuration file parse time, not during runtime. 1810.It Xo Ar queue Aq Ar queue 1811.No \*(Ba ( Aq Ar queue , 1812.Aq Ar queue ) 1813.Xc 1814Packets matching this rule will be assigned to the specified queue. 1815If two queues are given, packets which have a 1816.Em TOS 1817of 1818.Em lowdelay 1819and TCP ACKs with no data payload will be assigned to the second one. 1820See 1821.Sx QUEUEING 1822for setup details. 1823.Pp 1824For example: 1825.Bd -literal -offset indent 1826pass in proto tcp to port 25 queue mail 1827pass in proto tcp to port 22 queue(ssh_bulk, ssh_prio) 1828.Ed 1829.Pp 1830.It Cm set prio Ar priority | Pq Ar priority , priority 1831Packets matching this rule will be assigned a specific queueing priority. 1832Priorities are assigned as integers 0 through 7. 1833If the packet is transmitted on a 1834.Xr vlan 4 1835interface, the queueing priority will be written as the priority 1836code point in the 802.1Q VLAN header. 1837If two priorities are given, packets which have a TOS of 1838.Cm lowdelay 1839and TCP ACKs with no data payload will be assigned to the second one. 1840.Pp 1841For example: 1842.Bd -literal -offset indent 1843pass in proto tcp to port 25 set prio 2 1844pass in proto tcp to port 22 set prio (2, 5) 1845.Ed 1846.Pp 1847.It Ar tag Aq Ar string 1848Packets matching this rule will be tagged with the 1849specified string. 1850The tag acts as an internal marker that can be used to 1851identify these packets later on. 1852This can be used, for example, to provide trust between 1853interfaces and to determine if packets have been 1854processed by translation rules. 1855Tags are 1856.Qq sticky , 1857meaning that the packet will be tagged even if the rule 1858is not the last matching rule. 1859Further matching rules can replace the tag with a 1860new one but will not remove a previously applied tag. 1861A packet is only ever assigned one tag at a time. 1862Packet tagging can be done during 1863.Ar nat , 1864.Ar rdr , 1865or 1866.Ar binat 1867rules in addition to filter rules. 1868Tags take the same macros as labels (see above). 1869.It Ar tagged Aq Ar string 1870Used with filter, translation or scrub rules 1871to specify that packets must already 1872be tagged with the given tag in order to match the rule. 1873Inverse tag matching can also be done 1874by specifying the 1875.Cm !\& 1876operator before the 1877.Ar tagged 1878keyword. 1879.It Ar rtable Aq Ar number 1880Used to select an alternate routing table for the routing lookup. 1881Only effective before the route lookup happened, i.e. when filtering inbound. 1882.It Xo Ar divert-to Aq Ar host 1883.Ar port Aq Ar port 1884.Xc 1885Used to redirect packets to a local socket bound to 1886.Ar host 1887and 1888.Ar port . 1889The packets will not be modified, so 1890.Xr getsockname 2 1891on the socket will return the original destination address of the packet. 1892.It Ar divert-reply 1893Used to receive replies for sockets that are bound to addresses 1894which are not local to the machine. 1895See 1896.Xr setsockopt 2 1897for information on how to bind these sockets. 1898.It Ar probability Aq Ar number 1899A probability attribute can be attached to a rule, with a value set between 19000 and 1, bounds not included. 1901In that case, the rule will be honoured using the given probability value 1902only. 1903For example, the following rule will drop 20% of incoming ICMP packets: 1904.Bd -literal -offset indent 1905block in proto icmp probability 20% 1906.Ed 1907.It Ar prio Aq Ar number 1908Only match packets which have the given queueing priority assigned. 1909.Pp 1910.El 1911.Sh ROUTING 1912If a packet matches a rule with a route option set, the packet filter will 1913route the packet according to the type of route option. 1914When such a rule creates state, the route option is also applied to all 1915packets matching the same connection. 1916.Bl -tag -width xxxx 1917.It Ar route-to 1918The 1919.Ar route-to 1920option routes the packet to the specified interface with an optional address 1921for the next hop. 1922When a 1923.Ar route-to 1924rule creates state, only packets that pass in the same direction as the 1925filter rule specifies will be routed in this way. 1926Packets passing in the opposite direction (replies) are not affected 1927and are routed normally. 1928.It Ar reply-to 1929The 1930.Ar reply-to 1931option is similar to 1932.Ar route-to , 1933but routes packets that pass in the opposite direction (replies) to the 1934specified interface. 1935Opposite direction is only defined in the context of a state entry, and 1936.Ar reply-to 1937is useful only in rules that create state. 1938It can be used on systems with multiple external connections to 1939route all outgoing packets of a connection through the interface 1940the incoming connection arrived through (symmetric routing enforcement). 1941.It Ar dup-to 1942The 1943.Ar dup-to 1944option creates a duplicate of the packet and routes it like 1945.Ar route-to . 1946The original packet gets routed as it normally would. 1947.El 1948.Sh POOL OPTIONS 1949For 1950.Ar nat 1951and 1952.Ar rdr 1953rules, (as well as for the 1954.Ar route-to , 1955.Ar reply-to 1956and 1957.Ar dup-to 1958rule options) for which there is a single redirection address which has a 1959subnet mask smaller than 32 for IPv4 or 128 for IPv6 (more than one IP 1960address), a variety of different methods for assigning this address can be 1961used: 1962.Bl -tag -width xxxx 1963.It Ar bitmask 1964The 1965.Ar bitmask 1966option applies the network portion of the redirection address to the address 1967to be modified (source with 1968.Ar nat , 1969destination with 1970.Ar rdr ) . 1971.It Ar random 1972The 1973.Ar random 1974option selects an address at random within the defined block of addresses. 1975.It Ar source-hash 1976The 1977.Ar source-hash 1978option uses a hash of the source address to determine the redirection address, 1979ensuring that the redirection address is always the same for a given source. 1980An optional key can be specified after this keyword either in hex or as a 1981string; by default 1982.Xr pfctl 8 1983randomly generates a key for source-hash every time the 1984ruleset is reloaded. 1985.It Ar round-robin 1986The 1987.Ar round-robin 1988option loops through the redirection address(es). 1989.Pp 1990When more than one redirection address is specified, 1991.Ar round-robin 1992is the only permitted pool type. 1993.It Ar static-port 1994With 1995.Ar nat 1996rules, the 1997.Ar static-port 1998option prevents 1999.Xr pf 4 2000from modifying the source port on TCP and UDP packets. 2001.El 2002.Pp 2003Additionally, the 2004.Ar sticky-address 2005option can be specified to help ensure that multiple connections from the 2006same source are mapped to the same redirection address. 2007This option can be used with the 2008.Ar random 2009and 2010.Ar round-robin 2011pool options. 2012Note that by default these associations are destroyed as soon as there are 2013no longer states which refer to them; in order to make the mappings last 2014beyond the lifetime of the states, increase the global options with 2015.Ar set timeout src.track . 2016See 2017.Sx STATEFUL TRACKING OPTIONS 2018for more ways to control the source tracking. 2019.Sh STATE MODULATION 2020Much of the security derived from TCP is attributable to how well the 2021initial sequence numbers (ISNs) are chosen. 2022Some popular stack implementations choose 2023.Em very 2024poor ISNs and thus are normally susceptible to ISN prediction exploits. 2025By applying a 2026.Ar modulate state 2027rule to a TCP connection, 2028.Xr pf 4 2029will create a high quality random sequence number for each connection 2030endpoint. 2031.Pp 2032The 2033.Ar modulate state 2034directive implicitly keeps state on the rule and is 2035only applicable to TCP connections. 2036.Pp 2037For instance: 2038.Bd -literal -offset indent 2039block all 2040pass out proto tcp from any to any modulate state 2041pass in proto tcp from any to any port 25 flags S/SFRA modulate state 2042.Ed 2043.Pp 2044Note that modulated connections will not recover when the state table 2045is lost (firewall reboot, flushing the state table, etc...). 2046.Xr pf 4 2047will not be able to infer a connection again after the state table flushes 2048the connection's modulator. 2049When the state is lost, the connection may be left dangling until the 2050respective endpoints time out the connection. 2051It is possible on a fast local network for the endpoints to start an ACK 2052storm while trying to resynchronize after the loss of the modulator. 2053The default 2054.Ar flags 2055settings (or a more strict equivalent) should be used on 2056.Ar modulate state 2057rules to prevent ACK storms. 2058.Pp 2059Note that alternative methods are available 2060to prevent loss of the state table 2061and allow for firewall failover. 2062See 2063.Xr carp 4 2064and 2065.Xr pfsync 4 2066for further information. 2067.Sh SYN PROXY 2068By default, 2069.Xr pf 4 2070passes packets that are part of a 2071.Xr tcp 4 2072handshake between the endpoints. 2073The 2074.Ar synproxy state 2075option can be used to cause 2076.Xr pf 4 2077itself to complete the handshake with the active endpoint, perform a handshake 2078with the passive endpoint, and then forward packets between the endpoints. 2079.Pp 2080No packets are sent to the passive endpoint before the active endpoint has 2081completed the handshake, hence so-called SYN floods with spoofed source 2082addresses will not reach the passive endpoint, as the sender can't complete the 2083handshake. 2084.Pp 2085The proxy is transparent to both endpoints, they each see a single 2086connection from/to the other endpoint. 2087.Xr pf 4 2088chooses random initial sequence numbers for both handshakes. 2089Once the handshakes are completed, the sequence number modulators 2090(see previous section) are used to translate further packets of the 2091connection. 2092.Ar synproxy state 2093includes 2094.Ar modulate state . 2095.Pp 2096Rules with 2097.Ar synproxy 2098will not work if 2099.Xr pf 4 2100operates on a 2101.Xr bridge 4 . 2102.Pp 2103Example: 2104.Bd -literal -offset indent 2105pass in proto tcp from any to any port www synproxy state 2106.Ed 2107.Sh STATEFUL TRACKING OPTIONS 2108A number of options related to stateful tracking can be applied on a 2109per-rule basis. 2110.Ar keep state , 2111.Ar modulate state 2112and 2113.Ar synproxy state 2114support these options, and 2115.Ar keep state 2116must be specified explicitly to apply options to a rule. 2117.Pp 2118.Bl -tag -width xxxx -compact 2119.It Ar max Aq Ar number 2120Limits the number of concurrent states the rule may create. 2121When this limit is reached, further packets that would create 2122state will not match this rule until existing states time out. 2123.It Ar no-sync 2124Prevent state changes for states created by this rule from appearing on the 2125.Xr pfsync 4 2126interface. 2127.It Xo Aq Ar timeout 2128.Aq Ar seconds 2129.Xc 2130Changes the timeout values used for states created by this rule. 2131For a list of all valid timeout names, see 2132.Sx OPTIONS 2133above. 2134.It Ar sloppy 2135Uses a sloppy TCP connection tracker that does not check sequence 2136numbers at all, which makes insertion and ICMP teardown attacks way 2137easier. 2138This is intended to be used in situations where one does not see all 2139packets of a connection, e.g. in asymmetric routing situations. 2140Cannot be used with modulate or synproxy state. 2141.El 2142.Pp 2143Multiple options can be specified, separated by commas: 2144.Bd -literal -offset indent 2145pass in proto tcp from any to any \e 2146 port www keep state \e 2147 (max 100, source-track rule, max-src-nodes 75, \e 2148 max-src-states 3, tcp.established 60, tcp.closing 5) 2149.Ed 2150.Pp 2151When the 2152.Ar source-track 2153keyword is specified, the number of states per source IP is tracked. 2154.Pp 2155.Bl -tag -width xxxx -compact 2156.It Ar source-track rule 2157The maximum number of states created by this rule is limited by the rule's 2158.Ar max-src-nodes 2159and 2160.Ar max-src-states 2161options. 2162Only state entries created by this particular rule count toward the rule's 2163limits. 2164.It Ar source-track global 2165The number of states created by all rules that use this option is limited. 2166Each rule can specify different 2167.Ar max-src-nodes 2168and 2169.Ar max-src-states 2170options, however state entries created by any participating rule count towards 2171each individual rule's limits. 2172.El 2173.Pp 2174The following limits can be set: 2175.Pp 2176.Bl -tag -width xxxx -compact 2177.It Ar max-src-nodes Aq Ar number 2178Limits the maximum number of source addresses which can simultaneously 2179have state table entries. 2180.It Ar max-src-states Aq Ar number 2181Limits the maximum number of simultaneous state entries that a single 2182source address can create with this rule. 2183.El 2184.Pp 2185For stateful TCP connections, limits on established connections (connections 2186which have completed the TCP 3-way handshake) can also be enforced 2187per source IP. 2188.Pp 2189.Bl -tag -width xxxx -compact 2190.It Ar max-src-conn Aq Ar number 2191Limits the maximum number of simultaneous TCP connections which have 2192completed the 3-way handshake that a single host can make. 2193.It Xo Ar max-src-conn-rate Aq Ar number 2194.No / Aq Ar seconds 2195.Xc 2196Limit the rate of new connections over a time interval. 2197The connection rate is an approximation calculated as a moving average. 2198.El 2199.Pp 2200Because the 3-way handshake ensures that the source address is not being 2201spoofed, more aggressive action can be taken based on these limits. 2202With the 2203.Ar overload Aq Ar table 2204state option, source IP addresses which hit either of the limits on 2205established connections will be added to the named table. 2206This table can be used in the ruleset to block further activity from 2207the offending host, redirect it to a tarpit process, or restrict its 2208bandwidth. 2209.Pp 2210The optional 2211.Ar flush 2212keyword kills all states created by the matching rule which originate 2213from the host which exceeds these limits. 2214The 2215.Ar global 2216modifier to the flush command kills all states originating from the 2217offending host, regardless of which rule created the state. 2218.Pp 2219For example, the following rules will protect the webserver against 2220hosts making more than 100 connections in 10 seconds. 2221Any host which connects faster than this rate will have its address added 2222to the 2223.Aq bad_hosts 2224table and have all states originating from it flushed. 2225Any new packets arriving from this host will be dropped unconditionally 2226by the block rule. 2227.Bd -literal -offset indent 2228block quick from \*(Ltbad_hosts\*(Gt 2229pass in on $ext_if proto tcp to $webserver port www keep state \e 2230 (max-src-conn-rate 100/10, overload \*(Ltbad_hosts\*(Gt flush global) 2231.Ed 2232.Sh OPERATING SYSTEM FINGERPRINTING 2233Passive OS Fingerprinting is a mechanism to inspect nuances of a TCP 2234connection's initial SYN packet and guess at the host's operating system. 2235Unfortunately these nuances are easily spoofed by an attacker so the 2236fingerprint is not useful in making security decisions. 2237But the fingerprint is typically accurate enough to make policy decisions 2238upon. 2239.Pp 2240The fingerprints may be specified by operating system class, by 2241version, or by subtype/patchlevel. 2242The class of an operating system is typically the vendor or genre 2243and would be 2244.Ox 2245for the 2246.Xr pf 4 2247firewall itself. 2248The version of the oldest available 2249.Ox 2250release on the main FTP site 2251would be 2.6 and the fingerprint would be written 2252.Pp 2253.Dl \&"OpenBSD 2.6\&" 2254.Pp 2255The subtype of an operating system is typically used to describe the 2256patchlevel if that patch led to changes in the TCP stack behavior. 2257In the case of 2258.Ox , 2259the only subtype is for a fingerprint that was 2260normalized by the 2261.Ar no-df 2262scrub option and would be specified as 2263.Pp 2264.Dl \&"OpenBSD 3.3 no-df\&" 2265.Pp 2266Fingerprints for most popular operating systems are provided by 2267.Xr pf.os 5 . 2268Once 2269.Xr pf 4 2270is running, a complete list of known operating system fingerprints may 2271be listed by running: 2272.Pp 2273.Dl # pfctl -so 2274.Pp 2275Filter rules can enforce policy at any level of operating system specification 2276assuming a fingerprint is present. 2277Policy could limit traffic to approved operating systems or even ban traffic 2278from hosts that aren't at the latest service pack. 2279.Pp 2280The 2281.Ar unknown 2282class can also be used as the fingerprint which will match packets for 2283which no operating system fingerprint is known. 2284.Pp 2285Examples: 2286.Bd -literal -offset indent 2287pass out proto tcp from any os OpenBSD 2288block out proto tcp from any os Doors 2289block out proto tcp from any os "Doors PT" 2290block out proto tcp from any os "Doors PT SP3" 2291block out from any os "unknown" 2292pass on lo0 proto tcp from any os "OpenBSD 3.3 lo0" 2293.Ed 2294.Pp 2295Operating system fingerprinting is limited only to the TCP SYN packet. 2296This means that it will not work on other protocols and will not match 2297a currently established connection. 2298.Pp 2299Caveat: operating system fingerprints are occasionally wrong. 2300There are three problems: an attacker can trivially craft his packets to 2301appear as any operating system he chooses; 2302an operating system patch could change the stack behavior and no fingerprints 2303will match it until the database is updated; 2304and multiple operating systems may have the same fingerprint. 2305.Sh BLOCKING SPOOFED TRAFFIC 2306"Spoofing" is the faking of IP addresses, typically for malicious 2307purposes. 2308The 2309.Ar antispoof 2310directive expands to a set of filter rules which will block all 2311traffic with a source IP from the network(s) directly connected 2312to the specified interface(s) from entering the system through 2313any other interface. 2314.Pp 2315For example, the line 2316.Bd -literal -offset indent 2317antispoof for lo0 2318.Ed 2319.Pp 2320expands to 2321.Bd -literal -offset indent 2322block drop in on ! lo0 inet from 127.0.0.1/8 to any 2323block drop in on ! lo0 inet6 from ::1 to any 2324.Ed 2325.Pp 2326For non-loopback interfaces, there are additional rules to block incoming 2327packets with a source IP address identical to the interface's IP(s). 2328For example, assuming the interface wi0 had an IP address of 10.0.0.1 and a 2329netmask of 255.255.255.0, 2330the line 2331.Bd -literal -offset indent 2332antispoof for wi0 inet 2333.Ed 2334.Pp 2335expands to 2336.Bd -literal -offset indent 2337block drop in on ! wi0 inet from 10.0.0.0/24 to any 2338block drop in inet from 10.0.0.1 to any 2339.Ed 2340.Pp 2341Caveat: Rules created by the 2342.Ar antispoof 2343directive interfere with packets sent over loopback interfaces 2344to local addresses. 2345One should pass these explicitly. 2346.Sh FRAGMENT HANDLING 2347The size of IP datagrams (packets) can be significantly larger than the 2348maximum transmission unit (MTU) of the network. 2349In cases when it is necessary or more efficient to send such large packets, 2350the large packet will be fragmented into many smaller packets that will each 2351fit onto the wire. 2352Unfortunately for a firewalling device, only the first logical fragment will 2353contain the necessary header information for the subprotocol that allows 2354.Xr pf 4 2355to filter on things such as TCP ports or to perform NAT. 2356.Pp 2357Besides the use of 2358.Ar scrub 2359rules as described in 2360.Sx TRAFFIC NORMALIZATION 2361above, there are three options for handling fragments in the packet filter. 2362.Pp 2363One alternative is to filter individual fragments with filter rules. 2364If no 2365.Ar scrub 2366rule applies to a fragment, it is passed to the filter. 2367Filter rules with matching IP header parameters decide whether the 2368fragment is passed or blocked, in the same way as complete packets 2369are filtered. 2370Without reassembly, fragments can only be filtered based on IP header 2371fields (source/destination address, protocol), since subprotocol header 2372fields are not available (TCP/UDP port numbers, ICMP code/type). 2373The 2374.Ar fragment 2375option can be used to restrict filter rules to apply only to 2376fragments, but not complete packets. 2377Filter rules without the 2378.Ar fragment 2379option still apply to fragments, if they only specify IP header fields. 2380For instance, the rule 2381.Bd -literal -offset indent 2382pass in proto tcp from any to any port 80 2383.Ed 2384.Pp 2385never applies to a fragment, even if the fragment is part of a TCP 2386packet with destination port 80, because without reassembly this information 2387is not available for each fragment. 2388This also means that fragments cannot create new or match existing 2389state table entries, which makes stateful filtering and address 2390translation (NAT, redirection) for fragments impossible. 2391.Pp 2392It's also possible to reassemble only certain fragments by specifying 2393source or destination addresses or protocols as parameters in 2394.Ar scrub 2395rules. 2396.Pp 2397In most cases, the benefits of reassembly outweigh the additional 2398memory cost, and it's recommended to use 2399.Ar scrub 2400rules to reassemble 2401all fragments via the 2402.Ar fragment reassemble 2403modifier. 2404.Pp 2405The memory allocated for fragment caching can be limited using 2406.Xr pfctl 8 . 2407Once this limit is reached, fragments that would have to be cached 2408are dropped until other entries time out. 2409The timeout value can also be adjusted. 2410.Pp 2411When forwarding reassembled IPv6 packets, pf refragments them with 2412the original maximum fragment size. 2413This allows the sender to determine the optimal fragment size by 2414path MTU discovery. 2415.Sh ANCHORS 2416Besides the main ruleset, 2417.Xr pfctl 8 2418can load rulesets into 2419.Ar anchor 2420attachment points. 2421An 2422.Ar anchor 2423is a container that can hold rules, address tables, and other anchors. 2424.Pp 2425An 2426.Ar anchor 2427has a name which specifies the path where 2428.Xr pfctl 8 2429can be used to access the anchor to perform operations on it, such as 2430attaching child anchors to it or loading rules into it. 2431Anchors may be nested, with components separated by 2432.Sq / 2433characters, similar to how file system hierarchies are laid out. 2434The main ruleset is actually the default anchor, so filter and 2435translation rules, for example, may also be contained in any anchor. 2436.Pp 2437An anchor can reference another 2438.Ar anchor 2439attachment point 2440using the following kinds 2441of rules: 2442.Bl -tag -width xxxx 2443.It Ar nat-anchor Aq Ar name 2444Evaluates the 2445.Ar nat 2446rules in the specified 2447.Ar anchor . 2448.It Ar rdr-anchor Aq Ar name 2449Evaluates the 2450.Ar rdr 2451rules in the specified 2452.Ar anchor . 2453.It Ar binat-anchor Aq Ar name 2454Evaluates the 2455.Ar binat 2456rules in the specified 2457.Ar anchor . 2458.It Ar anchor Aq Ar name 2459Evaluates the filter rules in the specified 2460.Ar anchor . 2461.It Xo Ar load anchor 2462.Aq Ar name 2463.Ar from Aq Ar file 2464.Xc 2465Loads the rules from the specified file into the 2466anchor 2467.Ar name . 2468.El 2469.Pp 2470When evaluation of the main ruleset reaches an 2471.Ar anchor 2472rule, 2473.Xr pf 4 2474will proceed to evaluate all rules specified in that anchor. 2475.Pp 2476Matching filter and translation rules marked with the 2477.Ar quick 2478option are final and abort the evaluation of the rules in other 2479anchors and the main ruleset. 2480If the 2481.Ar anchor 2482itself is marked with the 2483.Ar quick 2484option, 2485ruleset evaluation will terminate when the anchor is exited if the packet is 2486matched by any rule within the anchor. 2487.Pp 2488.Ar anchor 2489rules are evaluated relative to the anchor in which they are contained. 2490For example, all 2491.Ar anchor 2492rules specified in the main ruleset will reference anchor 2493attachment points underneath the main ruleset, and 2494.Ar anchor 2495rules specified in a file loaded from a 2496.Ar load anchor 2497rule will be attached under that anchor point. 2498.Pp 2499Rules may be contained in 2500.Ar anchor 2501attachment points which do not contain any rules when the main ruleset 2502is loaded, and later such anchors can be manipulated through 2503.Xr pfctl 8 2504without reloading the main ruleset or other anchors. 2505For example, 2506.Bd -literal -offset indent 2507ext_if = \&"kue0\&" 2508block on $ext_if all 2509anchor spam 2510pass out on $ext_if all 2511pass in on $ext_if proto tcp from any \e 2512 to $ext_if port smtp 2513.Ed 2514.Pp 2515blocks all packets on the external interface by default, then evaluates 2516all rules in the 2517.Ar anchor 2518named "spam", and finally passes all outgoing connections and 2519incoming connections to port 25. 2520.Bd -literal -offset indent 2521# echo \&"block in quick from 1.2.3.4 to any\&" \&| \e 2522 pfctl -a spam -f - 2523.Ed 2524.Pp 2525This loads a single rule into the 2526.Ar anchor , 2527which blocks all packets from a specific address. 2528.Pp 2529The anchor can also be populated by adding a 2530.Ar load anchor 2531rule after the 2532.Ar anchor 2533rule: 2534.Bd -literal -offset indent 2535anchor spam 2536load anchor spam from "/etc/pf-spam.conf" 2537.Ed 2538.Pp 2539When 2540.Xr pfctl 8 2541loads 2542.Nm pf.conf , 2543it will also load all the rules from the file 2544.Pa /etc/pf-spam.conf 2545into the anchor. 2546.Pp 2547Optionally, 2548.Ar anchor 2549rules can specify packet filtering parameters using the same syntax as 2550filter rules. 2551When parameters are used, the 2552.Ar anchor 2553rule is only evaluated for matching packets. 2554This allows conditional evaluation of anchors, like: 2555.Bd -literal -offset indent 2556block on $ext_if all 2557anchor spam proto tcp from any to any port smtp 2558pass out on $ext_if all 2559pass in on $ext_if proto tcp from any to $ext_if port smtp 2560.Ed 2561.Pp 2562The rules inside 2563.Ar anchor 2564spam are only evaluated for 2565.Ar tcp 2566packets with destination port 25. 2567Hence, 2568.Bd -literal -offset indent 2569# echo \&"block in quick from 1.2.3.4 to any" \&| \e 2570 pfctl -a spam -f - 2571.Ed 2572.Pp 2573will only block connections from 1.2.3.4 to port 25. 2574.Pp 2575Anchors may end with the asterisk 2576.Pq Sq * 2577character, which signifies that all anchors attached at that point 2578should be evaluated in the alphabetical ordering of their anchor name. 2579For example, 2580.Bd -literal -offset indent 2581anchor "spam/*" 2582.Ed 2583.Pp 2584will evaluate each rule in each anchor attached to the 2585.Li spam 2586anchor. 2587Note that it will only evaluate anchors that are directly attached to the 2588.Li spam 2589anchor, and will not descend to evaluate anchors recursively. 2590.Pp 2591Since anchors are evaluated relative to the anchor in which they are 2592contained, there is a mechanism for accessing the parent and ancestor 2593anchors of a given anchor. 2594Similar to file system path name resolution, if the sequence 2595.Dq .. 2596appears as an anchor path component, the parent anchor of the current 2597anchor in the path evaluation at that point will become the new current 2598anchor. 2599As an example, consider the following: 2600.Bd -literal -offset indent 2601# echo ' anchor "spam/allowed" ' | pfctl -f - 2602# echo -e ' anchor "../banned" \en pass' | \e 2603 pfctl -a spam/allowed -f - 2604.Ed 2605.Pp 2606Evaluation of the main ruleset will lead into the 2607.Li spam/allowed 2608anchor, which will evaluate the rules in the 2609.Li spam/banned 2610anchor, if any, before finally evaluating the 2611.Ar pass 2612rule. 2613.Pp 2614Filter rule 2615.Ar anchors 2616can also be loaded inline in the ruleset within a brace ('{' '}') delimited 2617block. 2618Brace delimited blocks may contain rules or other brace-delimited blocks. 2619When anchors are loaded this way the anchor name becomes optional. 2620.Bd -literal -offset indent 2621anchor "external" on $ext_if { 2622 block 2623 anchor out { 2624 pass proto tcp from any to port { 25, 80, 443 } 2625 } 2626 pass in proto tcp to any port 22 2627} 2628.Ed 2629.Pp 2630Since the parser specification for anchor names is a string, any 2631reference to an anchor name containing 2632.Sq / 2633characters will require double quote 2634.Pq Sq \&" 2635characters around the anchor name. 2636.Sh TRANSLATION EXAMPLES 2637This example maps incoming requests on port 80 to port 8080, on 2638which a daemon is running (because, for example, it is not run as root, 2639and therefore lacks permission to bind to port 80). 2640.Bd -literal 2641# use a macro for the interface name, so it can be changed easily 2642ext_if = \&"ne3\&" 2643 2644# map daemon on 8080 to appear to be on 80 2645rdr on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 port 8080 2646.Ed 2647.Pp 2648If the 2649.Ar pass 2650modifier is given, packets matching the translation rule are passed without 2651inspecting the filter rules: 2652.Bd -literal 2653rdr pass on $ext_if proto tcp from any to any port 80 -\*(Gt 127.0.0.1 \e 2654 port 8080 2655.Ed 2656.Pp 2657In the example below, vlan12 is configured as 192.168.168.1; 2658the machine translates all packets coming from 192.168.168.0/24 to 204.92.77.111 2659when they are going out any interface except vlan12. 2660This has the net effect of making traffic from the 192.168.168.0/24 2661network appear as though it is the Internet routable address 2662204.92.77.111 to nodes behind any interface on the router except 2663for the nodes on vlan12. 2664(Thus, 192.168.168.1 can talk to the 192.168.168.0/24 nodes.) 2665.Bd -literal 2666nat on ! vlan12 from 192.168.168.0/24 to any -\*(Gt 204.92.77.111 2667.Ed 2668.Pp 2669In the example below, the machine sits between a fake internal 144.19.74.* 2670network, and a routable external IP of 204.92.77.100. 2671The 2672.Ar no nat 2673rule excludes protocol AH from being translated. 2674.Bd -literal 2675# NO NAT 2676no nat on $ext_if proto ah from 144.19.74.0/24 to any 2677nat on $ext_if from 144.19.74.0/24 to any -\*(Gt 204.92.77.100 2678.Ed 2679.Pp 2680In the example below, packets bound for one specific server, as well as those 2681generated by the sysadmins are not proxied; all other connections are. 2682.Bd -literal 2683# NO RDR 2684no rdr on $int_if proto { tcp, udp } from any to $server port 80 2685no rdr on $int_if proto { tcp, udp } from $sysadmins to any port 80 2686rdr on $int_if proto { tcp, udp } from any to any port 80 -\*(Gt 127.0.0.1 \e 2687 port 80 2688.Ed 2689.Pp 2690This longer example uses both a NAT and a redirection. 2691The external interface has the address 157.161.48.183. 2692On localhost, we are running 2693.Xr ftp-proxy 8 , 2694waiting for FTP sessions to be redirected to it. 2695The three mandatory anchors for 2696.Xr ftp-proxy 8 2697are omitted from this example; see the 2698.Xr ftp-proxy 8 2699manpage. 2700.Bd -literal 2701# NAT 2702# Translate outgoing packets' source addresses (any protocol). 2703# In this case, any address but the gateway's external address is mapped. 2704nat on $ext_if inet from ! ($ext_if) to any -\*(Gt ($ext_if) 2705 2706# NAT PROXYING 2707# Map outgoing packets' source port to an assigned proxy port instead of 2708# an arbitrary port. 2709# In this case, proxy outgoing isakmp with port 500 on the gateway. 2710nat on $ext_if inet proto udp from any port = isakmp to any -\*(Gt ($ext_if) \e 2711 port 500 2712 2713# BINAT 2714# Translate outgoing packets' source address (any protocol). 2715# Translate incoming packets' destination address to an internal machine 2716# (bidirectional). 2717binat on $ext_if from 10.1.2.150 to any -\*(Gt $ext_if 2718 2719# RDR 2720# Translate incoming packets' destination addresses. 2721# As an example, redirect a TCP and UDP port to an internal machine. 2722rdr on $ext_if inet proto tcp from any to ($ext_if) port 8080 \e 2723 -\*(Gt 10.1.2.151 port 22 2724rdr on $ext_if inet proto udp from any to ($ext_if) port 8080 \e 2725 -\*(Gt 10.1.2.151 port 53 2726 2727# RDR 2728# Translate outgoing ftp control connections to send them to localhost 2729# for proxying with ftp-proxy(8) running on port 8021. 2730rdr on $int_if proto tcp from any to any port 21 -\*(Gt 127.0.0.1 port 8021 2731.Ed 2732.Pp 2733In this example, a NAT gateway is set up to translate internal addresses 2734using a pool of public addresses (192.0.2.16/28) and to redirect 2735incoming web server connections to a group of web servers on the internal 2736network. 2737.Bd -literal 2738# NAT LOAD BALANCE 2739# Translate outgoing packets' source addresses using an address pool. 2740# A given source address is always translated to the same pool address by 2741# using the source-hash keyword. 2742nat on $ext_if inet from any to any -\*(Gt 192.0.2.16/28 source-hash 2743 2744# RDR ROUND ROBIN 2745# Translate incoming web server connections to a group of web servers on 2746# the internal network. 2747rdr on $ext_if proto tcp from any to any port 80 \e 2748 -\*(Gt { 10.1.2.155, 10.1.2.160, 10.1.2.161 } round-robin 2749.Ed 2750.Sh FILTER EXAMPLES 2751.Bd -literal 2752# The external interface is kue0 2753# (157.161.48.183, the only routable address) 2754# and the private network is 10.0.0.0/8, for which we are doing NAT. 2755 2756# use a macro for the interface name, so it can be changed easily 2757ext_if = \&"kue0\&" 2758 2759# normalize all incoming traffic 2760scrub in on $ext_if all fragment reassemble 2761 2762# block and log everything by default 2763block return log on $ext_if all 2764 2765# block anything coming from source we have no back routes for 2766block in from no-route to any 2767 2768# block packets whose ingress interface does not match the one in 2769# the route back to their source address 2770block in from urpf-failed to any 2771 2772# block and log outgoing packets that do not have our address as source, 2773# they are either spoofed or something is misconfigured (NAT disabled, 2774# for instance), we want to be nice and do not send out garbage. 2775block out log quick on $ext_if from ! 157.161.48.183 to any 2776 2777# silently drop broadcasts (cable modem noise) 2778block in quick on $ext_if from any to 255.255.255.255 2779 2780# block and log incoming packets from reserved address space and invalid 2781# addresses, they are either spoofed or misconfigured, we cannot reply to 2782# them anyway (hence, no return-rst). 2783block in log quick on $ext_if from { 10.0.0.0/8, 172.16.0.0/12, \e 2784 192.168.0.0/16, 255.255.255.255/32 } to any 2785 2786# ICMP 2787 2788# pass out/in certain ICMP queries and keep state (ping) 2789# state matching is done on host addresses and ICMP id (not type/code), 2790# so replies (like 0/0 for 8/0) will match queries 2791# ICMP error messages (which always refer to a TCP/UDP packet) are 2792# handled by the TCP/UDP states 2793pass on $ext_if inet proto icmp all icmp-type 8 code 0 2794 2795# UDP 2796 2797# pass out all UDP connections and keep state 2798pass out on $ext_if proto udp all 2799 2800# pass in certain UDP connections and keep state (DNS) 2801pass in on $ext_if proto udp from any to any port domain 2802 2803# TCP 2804 2805# pass out all TCP connections and modulate state 2806pass out on $ext_if proto tcp all modulate state 2807 2808# pass in certain TCP connections and keep state (SSH, SMTP, DNS, IDENT) 2809pass in on $ext_if proto tcp from any to any port { ssh, smtp, domain, \e 2810 auth } 2811 2812# Do not allow Windows 9x SMTP connections since they are typically 2813# a viral worm. Alternately we could limit these OSes to 1 connection each. 2814block in on $ext_if proto tcp from any os {"Windows 95", "Windows 98"} \e 2815 to any port smtp 2816 2817# IPv6 2818# pass in/out all IPv6 traffic: note that we have to enable this in two 2819# different ways, on both our physical interface and our tunnel 2820pass quick on gif0 inet6 2821pass quick on $ext_if proto ipv6 2822 2823# Packet Tagging 2824 2825# three interfaces: $int_if, $ext_if, and $wifi_if (wireless). NAT is 2826# being done on $ext_if for all outgoing packets. tag packets in on 2827# $int_if and pass those tagged packets out on $ext_if. all other 2828# outgoing packets (i.e., packets from the wireless network) are only 2829# permitted to access port 80. 2830 2831pass in on $int_if from any to any tag INTNET 2832pass in on $wifi_if from any to any 2833 2834block out on $ext_if from any to any 2835pass out quick on $ext_if tagged INTNET 2836pass out on $ext_if proto tcp from any to any port 80 2837 2838# tag incoming packets as they are redirected to spamd(8). use the tag 2839# to pass those packets through the packet filter. 2840 2841rdr on $ext_if inet proto tcp from \*(Ltspammers\*(Gt to port smtp \e 2842 tag SPAMD -\*(Gt 127.0.0.1 port spamd 2843 2844block in on $ext_if 2845pass in on $ext_if inet proto tcp tagged SPAMD 2846.Ed 2847.Sh GRAMMAR 2848Syntax for 2849.Nm 2850in BNF: 2851.Bd -literal 2852line = ( option | pf-rule | nat-rule | binat-rule | rdr-rule | 2853 antispoof-rule | altq-rule | queue-rule | trans-anchors | 2854 anchor-rule | anchor-close | load-anchor | table-rule | 2855 include ) 2856 2857option = "set" ( [ "timeout" ( timeout | "{" timeout-list "}" ) ] | 2858 [ "ruleset-optimization" [ "none" | "basic" | "profile" ]] | 2859 [ "optimization" [ "default" | "normal" | 2860 "high-latency" | "satellite" | 2861 "aggressive" | "conservative" ] ] 2862 [ "limit" ( limit-item | "{" limit-list "}" ) ] | 2863 [ "loginterface" ( interface-name | "none" ) ] | 2864 [ "block-policy" ( "drop" | "return" ) ] | 2865 [ "state-policy" ( "if-bound" | "floating" ) ] 2866 [ "state-defaults" state-opts ] 2867 [ "require-order" ( "yes" | "no" ) ] 2868 [ "fingerprints" filename ] | 2869 [ "skip on" ifspec ] | 2870 [ "debug" ( "none" | "urgent" | "misc" | "loud" ) ] ) 2871 2872pf-rule = action [ ( "in" | "out" ) ] 2873 [ "log" [ "(" logopts ")"] ] [ "quick" ] 2874 [ "on" ifspec ] [ route ] [ af ] [ protospec ] 2875 hosts [ filteropt-list ] 2876 2877logopts = logopt [ "," logopts ] 2878logopt = "all" | "user" | "to" interface-name 2879 2880filteropt-list = filteropt-list filteropt | filteropt 2881filteropt = user | group | flags | icmp-type | icmp6-type | "tos" tos | 2882 ( "no" | "keep" | "modulate" | "synproxy" ) "state" 2883 [ "(" state-opts ")" ] | 2884 "fragment" | "no-df" | "min-ttl" number | "set-tos" tos | 2885 "max-mss" number | "random-id" | "reassemble tcp" | 2886 fragmentation | "allow-opts" | 2887 "label" string | "tag" string | [ ! ] "tagged" string | 2888 "set prio" ( number | "(" number [ [ "," ] number ] ")" ) | 2889 "queue" ( string | "(" string [ [ "," ] string ] ")" ) | 2890 "rtable" number | "probability" number"%" | "prio" number 2891 2892nat-rule = [ "no" ] "nat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2893 [ "on" ifspec ] [ af ] 2894 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 2895 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" ) 2896 [ portspec ] [ pooltype ] [ "static-port" ] ] 2897 2898binat-rule = [ "no" ] "binat" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2899 [ "on" interface-name ] [ af ] 2900 [ "proto" ( proto-name | proto-number ) ] 2901 "from" address [ "/" mask-bits ] "to" ipspec 2902 [ "tag" string ] [ "tagged" string ] 2903 [ "-\*(Gt" address [ "/" mask-bits ] ] 2904 2905rdr-rule = [ "no" ] "rdr" [ "pass" [ "log" [ "(" logopts ")" ] ] ] 2906 [ "on" ifspec ] [ af ] 2907 [ protospec ] hosts [ "tag" string ] [ "tagged" string ] 2908 [ "-\*(Gt" ( redirhost | "{" redirhost-list "}" ) 2909 [ portspec ] [ pooltype ] ] 2910 2911antispoof-rule = "antispoof" [ "log" ] [ "quick" ] 2912 "for" ifspec [ af ] [ "label" string ] 2913 2914table-rule = "table" "\*(Lt" string "\*(Gt" [ tableopts-list ] 2915tableopts-list = tableopts-list tableopts | tableopts 2916tableopts = "persist" | "const" | "counters" | "file" string | 2917 "{" [ tableaddr-list ] "}" 2918tableaddr-list = tableaddr-list [ "," ] tableaddr-spec | tableaddr-spec 2919tableaddr-spec = [ "!" ] tableaddr [ "/" mask-bits ] 2920tableaddr = hostname | ifspec | "self" | 2921 ipv4-dotted-quad | ipv6-coloned-hex 2922 2923altq-rule = "altq on" interface-name queueopts-list 2924 "queue" subqueue 2925queue-rule = "queue" string [ "on" interface-name ] queueopts-list 2926 subqueue 2927 2928anchor-rule = "anchor" [ string ] [ ( "in" | "out" ) ] [ "on" ifspec ] 2929 [ af ] [ protospec ] [ hosts ] [ filteropt-list ] [ "{" ] 2930 2931anchor-close = "}" 2932 2933trans-anchors = ( "nat-anchor" | "rdr-anchor" | "binat-anchor" ) string 2934 [ "on" ifspec ] [ af ] [ "proto" ] [ protospec ] [ hosts ] 2935 2936load-anchor = "load anchor" string "from" filename 2937 2938queueopts-list = queueopts-list queueopts | queueopts 2939queueopts = [ "bandwidth" bandwidth-spec ] | 2940 [ "qlimit" number ] | [ "tbrsize" number ] | 2941 [ "priority" number ] | [ schedulers ] 2942schedulers = ( cbq-def | priq-def | hfsc-def ) 2943bandwidth-spec = "number" ( "b" | "Kb" | "Mb" | "Gb" | "%" ) 2944 2945action = "pass" | "block" [ return ] | [ "no" ] "scrub" 2946return = "drop" | "return" | "return-rst" [ "( ttl" number ")" ] | 2947 "return-icmp" [ "(" icmpcode [ [ "," ] icmp6code ] ")" ] | 2948 "return-icmp6" [ "(" icmp6code ")" ] 2949icmpcode = ( icmp-code-name | icmp-code-number ) 2950icmp6code = ( icmp6-code-name | icmp6-code-number ) 2951 2952ifspec = ( [ "!" ] ( interface-name | interface-group ) ) | 2953 "{" interface-list "}" 2954interface-list = [ "!" ] ( interface-name | interface-group ) 2955 [ [ "," ] interface-list ] 2956route = ( "route-to" | "reply-to" | "dup-to" ) 2957 ( routehost | "{" routehost-list "}" ) 2958 [ pooltype ] 2959af = "inet" | "inet6" 2960 2961protospec = "proto" ( proto-name | proto-number | 2962 "{" proto-list "}" ) 2963proto-list = ( proto-name | proto-number ) [ [ "," ] proto-list ] 2964 2965hosts = "all" | 2966 "from" ( "any" | "no-route" | "urpf-failed" | "self" | host | 2967 "{" host-list "}" ) [ port ] [ os ] 2968 "to" ( "any" | "no-route" | "self" | host | 2969 "{" host-list "}" ) [ port ] 2970 2971ipspec = "any" | host | "{" host-list "}" 2972host = [ "!" ] ( address [ "/" mask-bits ] | "\*(Lt" string "\*(Gt" ) 2973redirhost = address [ "/" mask-bits ] 2974routehost = "(" interface-name [ address [ "/" mask-bits ] ] ")" 2975address = ( interface-name | interface-group | 2976 "(" ( interface-name | interface-group ) ")" | 2977 hostname | ipv4-dotted-quad | ipv6-coloned-hex ) 2978host-list = host [ [ "," ] host-list ] 2979redirhost-list = redirhost [ [ "," ] redirhost-list ] 2980routehost-list = routehost [ [ "," ] routehost-list ] 2981 2982port = "port" ( unary-op | binary-op | "{" op-list "}" ) 2983portspec = "port" ( number | name ) [ ":" ( "*" | number | name ) ] 2984os = "os" ( os-name | "{" os-list "}" ) 2985user = "user" ( unary-op | binary-op | "{" op-list "}" ) 2986group = "group" ( unary-op | binary-op | "{" op-list "}" ) 2987 2988unary-op = [ "=" | "!=" | "\*(Lt" | "\*(Le" | "\*(Gt" | "\*(Ge" ] 2989 ( name | number ) 2990binary-op = number ( "\*(Lt\*(Gt" | "\*(Gt\*(Lt" | ":" ) number 2991op-list = ( unary-op | binary-op ) [ [ "," ] op-list ] 2992 2993os-name = operating-system-name 2994os-list = os-name [ [ "," ] os-list ] 2995 2996flags = "flags" ( [ flag-set ] "/" flag-set | "any" ) 2997flag-set = [ "F" ] [ "S" ] [ "R" ] [ "P" ] [ "A" ] [ "U" ] [ "E" ] 2998 [ "W" ] 2999 3000icmp-type = "icmp-type" ( icmp-type-code | "{" icmp-list "}" ) 3001icmp6-type = "icmp6-type" ( icmp-type-code | "{" icmp-list "}" ) 3002icmp-type-code = ( icmp-type-name | icmp-type-number ) 3003 [ "code" ( icmp-code-name | icmp-code-number ) ] 3004icmp-list = icmp-type-code [ [ "," ] icmp-list ] 3005 3006tos = ( "lowdelay" | "throughput" | "reliability" | 3007 [ "0x" ] number ) 3008 3009state-opts = state-opt [ [ "," ] state-opts ] 3010state-opt = ( "max" number | "no-sync" | timeout | "sloppy" | 3011 "source-track" [ ( "rule" | "global" ) ] | 3012 "max-src-nodes" number | "max-src-states" number | 3013 "max-src-conn" number | 3014 "max-src-conn-rate" number "/" number | 3015 "overload" "\*(Lt" string "\*(Gt" [ "flush" ] | 3016 "if-bound" | "floating" ) 3017 3018fragmentation = [ "fragment reassemble" ] 3019 3020timeout-list = timeout [ [ "," ] timeout-list ] 3021timeout = ( "tcp.first" | "tcp.opening" | "tcp.established" | 3022 "tcp.closing" | "tcp.finwait" | "tcp.closed" | 3023 "udp.first" | "udp.single" | "udp.multiple" | 3024 "icmp.first" | "icmp.error" | 3025 "other.first" | "other.single" | "other.multiple" | 3026 "frag" | "interval" | "src.track" | 3027 "adaptive.start" | "adaptive.end" ) number 3028 3029limit-list = limit-item [ [ "," ] limit-list ] 3030limit-item = ( "states" | "frags" | "src-nodes" ) number 3031 3032pooltype = ( "bitmask" | "random" | 3033 "source-hash" [ ( hex-key | string-key ) ] | 3034 "round-robin" ) [ sticky-address ] 3035 3036subqueue = string | "{" queue-list "}" 3037queue-list = string [ [ "," ] string ] 3038cbq-def = "cbq" [ "(" cbq-opt [ [ "," ] cbq-opt ] ")" ] 3039priq-def = "priq" [ "(" priq-opt [ [ "," ] priq-opt ] ")" ] 3040hfsc-def = "hfsc" [ "(" hfsc-opt [ [ "," ] hfsc-opt ] ")" ] 3041cbq-opt = ( "default" | "borrow" | "red" | "ecn" | "rio" ) 3042priq-opt = ( "default" | "red" | "ecn" | "rio" ) 3043hfsc-opt = ( "default" | "red" | "ecn" | "rio" | 3044 linkshare-sc | realtime-sc | upperlimit-sc ) 3045linkshare-sc = "linkshare" sc-spec 3046realtime-sc = "realtime" sc-spec 3047upperlimit-sc = "upperlimit" sc-spec 3048sc-spec = ( bandwidth-spec | 3049 "(" bandwidth-spec number bandwidth-spec ")" ) 3050include = "include" filename 3051.Ed 3052.Sh FILES 3053.Bl -tag -width "/etc/protocols" -compact 3054.It Pa /etc/hosts 3055Host name database. 3056.It Pa /etc/pf.conf 3057Default location of the ruleset file. 3058The file has to be created manually as it is not installed with a 3059standard installation. 3060.It Pa /etc/pf.os 3061Default location of OS fingerprints. 3062.It Pa /etc/protocols 3063Protocol name database. 3064.It Pa /etc/services 3065Service name database. 3066.El 3067.Sh SEE ALSO 3068.Xr altq 4 , 3069.Xr carp 4 , 3070.Xr icmp 4 , 3071.Xr icmp6 4 , 3072.Xr ip 4 , 3073.Xr ip6 4 , 3074.Xr pf 4 , 3075.Xr pfsync 4 , 3076.Xr tcp 4 , 3077.Xr udp 4 , 3078.Xr hosts 5 , 3079.Xr pf.os 5 , 3080.Xr protocols 5 , 3081.Xr services 5 , 3082.Xr ftp-proxy 8 , 3083.Xr pfctl 8 , 3084.Xr pflogd 8 3085.Sh HISTORY 3086The 3087.Nm 3088file format first appeared in 3089.Ox 3.0 . 3090