1 .\" $OpenBSD: pf.4,v 1.62 2008/09/10 14:57:37 jmc Exp $
3 .\" Copyright (C) 2001, Kjell Wooding. All rights reserved.
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40 Packet filtering takes place in the kernel.
43 allows userland processes to control the
44 behavior of the packet filter through an
47 There are commands to enable and disable the filter, load rulesets,
48 add and remove individual rules or state table entries,
49 and retrieve statistics.
50 The most commonly used functions are covered by
53 Manipulations like loading a ruleset that involve more than a single
55 call require a so-called
57 which prevents the occurrence of
58 multiple concurrent manipulations.
62 parameter structures that refer to packet data (like
63 addresses and ports) are generally expected in network byte-order.
65 Rules and address tables are contained in so-called
69 request, if the anchor field of the argument structure is empty,
70 the kernel will use the default anchor (i.e., the main ruleset)
72 Anchors are specified by name and may be nested, with components
75 characters, similar to how file system hierarchies are laid out.
76 The final component of the anchor path is the anchor under which
77 operations will be performed.
80 supports the following
82 commands, available through
84 .Bl -tag -width xxxxxx
86 Start the packet filter.
88 Stop the packet filter.
90 Start the ALTQ bandwidth control system (see
93 Stop the ALTQ bandwidth control system.
94 .It Dv DIOCBEGINADDRS Fa "struct pfioc_pooladdr *pp"
96 struct pfioc_pooladdr {
104 char anchor[MAXPATHLEN];
105 struct pf_pooladdr addr;
109 Clear the buffer address pool and get a
117 .It Dv DIOCADDADDR Fa "struct pfioc_pooladdr *pp"
121 to the buffer address pool to be used in the following
126 All other members of the structure are ignored.
127 .It Dv DIOCADDRULE Fa "struct pfioc_rule *pr"
132 u_int32_t pool_ticket;
134 char anchor[MAXPATHLEN];
135 char anchor_call[MAXPATHLEN];
142 at the end of the inactive ruleset.
145 obtained through a preceding
153 must also be called if any pool addresses are required.
156 name indicates the anchor in which to append the rule.
161 .It Dv DIOCADDALTQ Fa "struct pfioc_altq *pa"
162 Add an ALTQ discipline or queue.
171 .It Dv DIOCGETRULES Fa "struct pfioc_rule *pr"
178 of rules in the active ruleset.
179 .It Dv DIOCGETRULE Fa "struct pfioc_rule *pr"
186 obtained through a preceding
192 .Dv PF_GET_CLR_CNTR ,
193 the per-rule statistics on the requested rule are cleared.
194 .It Dv DIOCGETADDRS Fa "struct pfioc_pooladdr *pp"
201 of pool addresses in the rule specified with
206 .It Dv DIOCGETADDR Fa "struct pfioc_pooladdr *pp"
211 from the rule specified with
218 obtained through a preceding
221 .It Dv DIOCGETALTQS Fa "struct pfioc_altq *pa"
228 of queues in the active list.
229 .It Dv DIOCGETALTQ Fa "struct pfioc_altq *pa"
230 Get the queueing discipline
236 obtained through a preceding
239 .It Dv DIOCGETQSTATS Fa "struct pfioc_qstats *pq"
240 Get the statistics on a queue.
242 struct pfioc_qstats {
251 This call fills in a pointer to the buffer of statistics
255 for the queue specified by
257 .It Dv DIOCGETRULESETS Fa "struct pfioc_ruleset *pr"
259 struct pfioc_ruleset {
261 char path[MAXPATHLEN];
262 char name[PF_ANCHOR_NAME_SIZE];
268 of rulesets (i.e., anchors) directly attached to the anchor named by
270 for use in subsequent
273 Nested anchors, since they are not directly attached to the given
274 anchor, will not be included.
277 if the given anchor does not exist.
278 .It Dv DIOCGETRULESET Fa "struct pfioc_ruleset *pr"
279 Get a ruleset (i.e., an anchor)
283 from the given anchor
285 the maximum number of which can be obtained from a preceding
290 if the given anchor does not exist or
292 if another process is concurrently updating a ruleset.
293 .It Dv DIOCADDSTATE Fa "struct pfioc_state *ps"
297 struct pfsync_state state;
300 .It Dv DIOCGETSTATE Fa "struct pfioc_state *ps"
301 Extract the entry identified by the
307 structure from the state table.
308 .It Dv DIOCKILLSTATES Fa "struct pfioc_state_kill *psk"
309 Remove matching entries from the state table.
310 This ioctl returns the number of killed states in
313 struct pfioc_state_kill {
314 struct pf_state_cmp psk_pfcmp;
317 struct pf_rule_addr psk_src;
318 struct pf_rule_addr psk_dst;
319 char psk_ifname[IFNAMSIZ];
320 char psk_label[PF_RULE_LABEL_SIZE];
324 .It Dv DIOCCLRSTATES Fa "struct pfioc_state_kill *psk"
337 .It Dv DIOCSETSTATUSIF Fa "struct pfioc_if *pi"
338 Specify the interface for which statistics are accumulated.
341 char ifname[IFNAMSIZ];
344 .It Dv DIOCGETSTATUS Fa "struct pf_status *s"
345 Get the internal packet filter statistics.
348 u_int64_t counters[PFRES_MAX];
349 u_int64_t lcounters[LCNT_MAX];
350 u_int64_t fcounters[FCNT_MAX];
351 u_int64_t scounters[SCNT_MAX];
352 u_int64_t pcounters[2][2][3];
353 u_int64_t bcounters[2][2];
361 char ifname[IFNAMSIZ];
362 u_int8_t pf_chksum[MD5_DIGEST_LENGTH];
366 Clear the internal packet filter statistics.
367 .It Dv DIOCNATLOOK Fa "struct pfioc_natlook *pnl"
368 Look up a state table entry by source and destination addresses and ports.
370 struct pfioc_natlook {
371 struct pf_addr saddr;
372 struct pf_addr daddr;
373 struct pf_addr rsaddr;
374 struct pf_addr rdaddr;
384 .It Dv DIOCSETDEBUG Fa "u_int32_t *level"
387 enum { PF_DEBUG_NONE, PF_DEBUG_URGENT, PF_DEBUG_MISC,
390 .It Dv DIOCGETSTATES Fa "struct pfioc_states *ps"
391 Get state table entries.
393 struct pfioc_states {
397 struct pf_state *psu_states;
399 #define ps_buf ps_u.psu_buf
400 #define ps_states ps_u.psu_states
406 is non-zero on entry, as many states as possible that can fit into this
407 size will be copied into the supplied buffer
411 is always set to the total size required to hold all state table entries
413 .Li sizeof(struct pf_state) * nr ) .
414 .It Dv DIOCCHANGERULE Fa "struct pfioc_rule *pcr"
417 in the ruleset specified by
420 The type of operation to be performed is indicated by
422 which can be any of the following:
424 enum { PF_CHANGE_NONE, PF_CHANGE_ADD_HEAD, PF_CHANGE_ADD_TAIL,
425 PF_CHANGE_ADD_BEFORE, PF_CHANGE_ADD_AFTER,
426 PF_CHANGE_REMOVE, PF_CHANGE_GET_TICKET };
430 must be set to the value obtained with
431 .Dv PF_CHANGE_GET_TICKET
432 for all actions except
433 .Dv PF_CHANGE_GET_TICKET .
435 must be set to the value obtained with the
437 call for all actions except
440 .Dv PF_CHANGE_GET_TICKET .
442 indicates to which anchor the operation applies.
444 indicates the rule number against which
445 .Dv PF_CHANGE_ADD_BEFORE ,
446 .Dv PF_CHANGE_ADD_AFTER ,
450 .\" It Dv DIOCCHANGEALTQ Fa "struct pfioc_altq *pcr"
451 .It Dv DIOCCHANGEADDR Fa "struct pfioc_pooladdr *pca"
452 Add or remove the pool address
454 from the rule specified by
459 .It Dv DIOCSETTIMEOUT Fa "struct pfioc_tm *pt"
467 Set the state timeout of
471 The old value will be placed into
473 For possible values of
479 .It Dv DIOCGETTIMEOUT Fa "struct pfioc_tm *pt"
480 Get the state timeout of
482 The value will be placed into the
485 .It Dv DIOCCLRRULECTRS
486 Clear per-rule statistics.
487 .It Dv DIOCSETLIMIT Fa "struct pfioc_limit *pl"
488 Set the hard limits on the memory pools used by the packet filter.
495 enum { PF_LIMIT_STATES, PF_LIMIT_SRC_NODES, PF_LIMIT_FRAGS,
496 PF_LIMIT_TABLES, PF_LIMIT_TABLE_ENTRIES, PF_LIMIT_MAX };
498 .It Dv DIOCGETLIMIT Fa "struct pfioc_limit *pl"
501 for the memory pool indicated by
503 .It Dv DIOCRCLRTABLES Fa "struct pfioc_table *io"
505 All the ioctls that manipulate radix tables
506 use the same structure described below.
510 contains on exit the number of tables deleted.
513 struct pfr_table pfrio_table;
522 u_int32_t pfrio_ticket;
524 #define pfrio_exists pfrio_nadd
525 #define pfrio_nzero pfrio_nadd
526 #define pfrio_nmatch pfrio_nadd
527 #define pfrio_naddr pfrio_size2
528 #define pfrio_setflag pfrio_size2
529 #define pfrio_clrflag pfrio_nadd
531 .It Dv DIOCRADDTABLES Fa "struct pfioc_table *io"
532 Create one or more tables.
535 must point to an array of
542 .Vt struct pfr_table .
545 contains the number of tables effectively created.
548 char pfrt_anchor[MAXPATHLEN];
549 char pfrt_name[PF_TABLE_NAME_SIZE];
550 u_int32_t pfrt_flags;
554 .It Dv DIOCRDELTABLES Fa "struct pfioc_table *io"
555 Delete one or more tables.
558 must point to an array of
565 .Vt struct pfr_table .
568 contains the number of tables effectively deleted.
569 .It Dv DIOCRGETTABLES Fa "struct pfioc_table *io"
570 Get the list of all tables.
572 .Va pfrio_buffer[pfrio_size]
573 contains a valid writeable buffer for
578 contains the number of tables written into the buffer.
579 If the buffer is too small, the kernel does not store anything but just
580 returns the required buffer size, without error.
581 .It Dv DIOCRGETTSTATS Fa "struct pfioc_table *io"
584 but is used to get an array of
589 struct pfr_table pfrts_t;
590 u_int64_t pfrts_packets
591 [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
592 u_int64_t pfrts_bytes
593 [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
594 u_int64_t pfrts_match;
595 u_int64_t pfrts_nomatch;
598 int pfrts_refcnt[PFR_REFCNT_MAX];
600 #define pfrts_name pfrts_t.pfrt_name
601 #define pfrts_flags pfrts_t.pfrt_flags
603 .It Dv DIOCRCLRTSTATS Fa "struct pfioc_table *io"
604 Clear the statistics of one or more tables.
607 must point to an array of
614 .Vt struct pfr_table .
617 contains the number of tables effectively cleared.
618 .It Dv DIOCRCLRADDRS Fa "struct pfioc_table *io"
619 Clear all addresses in a table.
622 contains the table to clear.
625 contains the number of addresses removed.
626 .It Dv DIOCRADDADDRS Fa "struct pfioc_table *io"
627 Add one or more addresses to a table.
630 contains the table ID and
632 must point to an array of
636 elements to add to the table.
639 .Vt struct pfr_addr .
642 contains the number of addresses effectively added.
646 struct in_addr _pfra_ip4addr;
647 struct in6_addr _pfra_ip6addr;
654 #define pfra_ip4addr pfra_u._pfra_ip4addr
655 #define pfra_ip6addr pfra_u._pfra_ip6addr
657 .It Dv DIOCRDELADDRS Fa "struct pfioc_table *io"
658 Delete one or more addresses from a table.
661 contains the table ID and
663 must point to an array of
667 elements to delete from the table.
670 .Vt struct pfr_addr .
673 contains the number of addresses effectively deleted.
674 .It Dv DIOCRSETADDRS Fa "struct pfioc_table *io"
675 Replace the content of a table by a new address list.
676 This is the most complicated command, which uses all the structure members.
680 contains the table ID and
682 must point to an array of
686 elements which become the new contents of the table.
689 .Vt struct pfr_addr .
693 .Va pfrio_buffer[pfrio_size..pfrio_size2]
694 must be a writeable buffer, into which the kernel can copy the
695 addresses that have been deleted during the replace operation.
701 contain the number of addresses deleted, added, and changed by the
707 will point to the size of the buffer used, exactly like
709 .It Dv DIOCRGETADDRS Fa "struct pfioc_table *io"
710 Get all the addresses of a table.
713 contains the table ID and
714 .Va pfrio_buffer[pfrio_size]
715 contains a valid writeable buffer for
720 contains the number of addresses written into the buffer.
721 If the buffer was too small, the kernel does not store anything but just
722 returns the required buffer size, without returning an error.
723 .It Dv DIOCRGETASTATS Fa "struct pfioc_table *io"
726 but is used to get an array of
731 struct pfr_addr pfras_a;
732 u_int64_t pfras_packets
733 [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
734 u_int64_t pfras_bytes
735 [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
739 .It Dv DIOCRCLRASTATS Fa "struct pfioc_table *io"
740 Clear the statistics of one or more addresses.
743 contains the table ID and
745 must point to an array of
749 elements to be cleared from the table.
752 .Vt struct pfr_addr .
755 contains the number of addresses effectively cleared.
756 .It Dv DIOCRTSTADDRS Fa "struct pfioc_table *io"
757 Test if the given addresses match a table.
760 contains the table ID and
762 must point to an array of
766 elements, each of which will be tested for a match in the table.
769 .Vt struct pfr_addr .
770 On exit, the kernel updates the
774 member appropriately.
775 .It Dv DIOCRSETTFLAGS Fa "struct pfioc_table *io"
779 .Dv PFR_TFLAG_PERSIST
783 must point to an array of
790 .Vt struct pfr_table .
792 must contain the flags to add, while
794 must contain the flags to remove.
799 contain the number of tables altered or deleted by the kernel.
800 Yes, tables can be deleted if one removes the
801 .Dv PFR_TFLAG_PERSIST
802 flag of an unreferenced table.
803 .It Dv DIOCRINADEFINE Fa "struct pfioc_table *io"
804 Defines a table in the inactive set.
807 contains the table ID and
808 .Va pfrio_buffer[pfrio_size]
811 structures to put in the table.
812 A valid ticket must also be supplied to
816 contains 0 if the table was already defined in the inactive list
817 or 1 if a new table has been created.
819 contains the number of addresses effectively put in the table.
820 .It Dv DIOCXBEGIN Fa "struct pfioc_trans *io"
823 int size; /* number of elements */
824 int esize; /* size of each element in bytes */
825 struct pfioc_trans_e {
827 char anchor[MAXPATHLEN];
833 Clear all the inactive rulesets specified in the
836 For each ruleset, a ticket is returned for subsequent "add rule" ioctls,
843 Ruleset types, identified by
845 include the following:
847 .Bl -tag -width PF_RULESET_FILTER -offset ind -compact
848 .It Dv PF_RULESET_SCRUB
849 Scrub (packet normalization) rules.
850 .It Dv PF_RULESET_FILTER
852 .It Dv PF_RULESET_NAT
853 NAT (Network Address Translation) rules.
854 .It Dv PF_RULESET_BINAT
855 Bidirectional NAT rules.
856 .It Dv PF_RULESET_RDR
858 .It Dv PF_RULESET_ALTQ
860 .It Dv PF_RULESET_TABLE
863 .It Dv DIOCXCOMMIT Fa "struct pfioc_trans *io"
864 Atomically switch a vector of inactive rulesets to the active rulesets.
865 This call is implemented as a standard two-phase commit, which will either
866 fail for all rulesets or completely succeed.
867 All tickets need to be valid.
870 if another process is concurrently updating some of the same rulesets.
871 .It Dv DIOCXROLLBACK Fa "struct pfioc_trans *io"
872 Clean up the kernel by undoing all changes that have taken place on the
873 inactive rulesets since the last
876 will silently ignore rulesets for which the ticket is invalid.
877 .It Dv DIOCSETHOSTID Fa "u_int32_t *hostid"
878 Set the host ID, which is used by
880 to identify which host created state table entries.
882 Flush the passive OS fingerprint table.
883 .It Dv DIOCOSFPADD Fa "struct pf_osfp_ioctl *io"
885 struct pf_osfp_ioctl {
886 struct pf_osfp_entry {
887 SLIST_ENTRY(pf_osfp_entry) fp_entry;
889 char fp_class_nm[PF_OSFP_LEN];
890 char fp_version_nm[PF_OSFP_LEN];
891 char fp_subtype_nm[PF_OSFP_LEN];
893 pf_tcpopts_t fp_tcpopts;
905 Add a passive OS fingerprint to the table.
908 to the packed fingerprint,
909 .Va fp_os.fp_class_nm
910 to the name of the class (Linux, Windows, etc),
911 .Va fp_os.fp_version_nm
912 to the name of the version (NT, 95, 98), and
913 .Va fp_os.fp_subtype_nm
914 to the name of the subtype or patchlevel.
923 are set to the TCP MSS, the TCP window size, the IP length, the IP TTL,
924 the number of TCP options, and the TCP window scaling constant of the
925 TCP SYN packet, respectively.
929 member is filled according to the
936 member contains packed TCP options.
938 .Dv PF_OSFP_TCPOPT_BITS
939 bits in the packed value.
940 Options include any of
941 .Dv PF_OSFP_TCPOPT_NOP ,
942 .Dv PF_OSFP_TCPOPT_SACK ,
943 .Dv PF_OSFP_TCPOPT_WSCALE ,
944 .Dv PF_OSFP_TCPOPT_MSS ,
946 .Dv PF_OSFP_TCPOPT_TS .
950 member is not used with this ioctl.
952 The structure's slack space must be zeroed for correct operation;
954 the whole structure to zero before filling and sending to the kernel.
955 .It Dv DIOCOSFPGET Fa "struct pf_osfp_ioctl *io"
956 Get the passive OS fingerprint number
958 from the kernel's fingerprint list.
959 The rest of the structure members will come back filled.
960 Get the whole list by repeatedly incrementing the
962 number until the ioctl returns
964 .It Dv DIOCGETSRCNODES Fa "struct pfioc_src_nodes *psn"
966 struct pfioc_src_nodes {
970 struct pf_src_node *psu_src_nodes;
972 #define psn_buf psn_u.psu_buf
973 #define psn_src_nodes psn_u.psu_src_nodes
977 Get the list of source nodes kept by sticky addresses and source
979 The ioctl must be called once with
982 If the ioctl returns without error,
984 will be set to the size of the buffer required to hold all the
986 structures held in the table.
987 A buffer of this size should then be allocated, and a pointer to this buffer
990 The ioctl must then be called again to fill this buffer with the actual
994 will be set to the length of the buffer actually used.
995 .It Dv DIOCCLRSRCNODES
996 Clear the tree of source tracking nodes.
997 .It Dv DIOCIGETIFACES Fa "struct pfioc_iface *io"
998 Get the list of interfaces and interface drivers known to
1000 All the ioctls that manipulate interfaces
1001 use the same structure described below:
1003 struct pfioc_iface {
1004 char pfiio_name[IFNAMSIZ];
1015 can be used to restrict the search to a specific interface or driver.
1016 .Va pfiio_buffer[pfiio_size]
1017 is the user-supplied buffer for returning the data.
1020 contains the number of
1022 entries that can fit into the buffer.
1023 The kernel will replace this value by the real number of entries it wants
1027 .Li sizeof(struct pfi_kif) .
1029 The data is returned in the
1031 structure described below:
1034 RB_ENTRY(pfi_kif) pfik_tree;
1035 char pfik_name[IFNAMSIZ];
1036 u_int64_t pfik_packets[2][2][2];
1037 u_int64_t pfik_bytes[2][2][2];
1038 u_int32_t pfik_tzero;
1040 struct pf_state_tree_lan_ext pfik_lan_ext;
1041 struct pf_state_tree_ext_gwy pfik_ext_gwy;
1042 TAILQ_ENTRY(pfi_kif) pfik_w_states;
1043 void *pfik_ah_cookie;
1044 struct ifnet *pfik_ifp;
1045 struct ifg_group *pfik_group;
1048 TAILQ_HEAD(, pfi_dynaddr) pfik_dynaddrs;
1051 .It Dv DIOCSETIFFLAG Fa "struct pfioc_iface *io"
1052 Set the user setable flags (described above) of the
1054 internal interface description.
1055 The filtering process is the same as for
1056 .Dv DIOCIGETIFACES .
1058 #define PFI_IFLAG_SKIP 0x0100 /* skip filtering on interface */
1060 .It Dv DIOCCLRIFFLAG Fa "struct pfioc_iface *io"
1063 above but clears the flags.
1064 .It Dv DIOCKILLSRCNODES Fa "struct pfioc_iface *io"
1065 Explicitly remove source tracking nodes.
1068 .Bl -tag -width /dev/pf -compact
1070 packet filtering device.
1073 The following example demonstrates how to use the
1075 command to find the internal host/port of a NATed connection:
1077 #include <sys/types.h>
1078 #include <sys/socket.h>
1079 #include <sys/ioctl.h>
1080 #include <sys/fcntl.h>
1082 #include <netinet/in.h>
1083 #include <net/pfvar.h>
1089 read_address(const char *s)
1093 sscanf(s, "%i.%i.%i.%i", &a, &b, &c, &d);
1094 return htonl(a << 24 | b << 16 | c << 8 | d);
1098 print_address(u_int32_t a)
1101 printf("%d.%d.%d.%d", a >> 24 & 255, a >> 16 & 255,
1102 a >> 8 & 255, a & 255);
1106 main(int argc, char *argv[])
1108 struct pfioc_natlook nl;
1112 printf("%s <gwy addr> <gwy port> <ext addr> <ext port>\\n",
1117 dev = open("/dev/pf", O_RDWR);
1119 err(1, "open(\\"/dev/pf\\") failed");
1121 memset(&nl, 0, sizeof(struct pfioc_natlook));
1122 nl.saddr.v4.s_addr = read_address(argv[1]);
1123 nl.sport = htons(atoi(argv[2]));
1124 nl.daddr.v4.s_addr = read_address(argv[3]);
1125 nl.dport = htons(atoi(argv[4]));
1127 nl.proto = IPPROTO_TCP;
1128 nl.direction = PF_IN;
1130 if (ioctl(dev, DIOCNATLOOK, &nl))
1131 err(1, "DIOCNATLOOK");
1133 printf("internal host ");
1134 print_address(nl.rsaddr.v4.s_addr);
1135 printf(":%u\\n", ntohs(nl.rsport));
1151 packet filtering mechanism first appeared in
1156 This implementation matches