1 .\" $OpenBSD: pf.4,v 1.48 2004/03/27 17:15:30 henning Exp $
3 .\" Copyright (C) 2001, Kjell Wooding. All rights reserved.
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38 .Cd "options PFIL_HOOKS"
41 Packet filtering takes place in the kernel.
44 allows userland processes to control the
45 behavior of the packet filter through an
48 There are commands to enable and disable the filter, load rulesets,
49 add and remove individual rules or state table entries,
50 and retrieve statistics.
51 The most commonly used functions are covered by
54 Manipulations like loading a ruleset that involve more than a single
55 ioctl call require a so-called ticket, which prevents the occurrence of
56 multiple concurrent manipulations.
58 Fields of ioctl parameter structures that refer to packet data (like
59 addresses and ports) are generally expected in network byte-order.
61 .Bl -tag -width /dev/pf -compact
63 packet filtering device.
66 pf supports the following
69 .Bl -tag -width xxxxxx
71 Starts the packet filter.
73 Stops the packet filter.
75 Starts the ALTQ bandwidth control system.
77 Stops the ALTQ bandwidth control system.
78 .It Dv DIOCBEGINADDRS Fa "struct pfioc_pooladdr"
80 struct pfioc_pooladdr {
88 char anchor[PF_ANCHOR_NAME_SIZE];
89 char ruleset[PF_RULESET_NAME_SIZE];
90 struct pf_pooladdr addr;
94 Clears the buffer address pool
97 for subsequent DIOCADDADDR, DIOCADDRULE and DIOCCHANGERULE calls.
98 .It Dv DIOCADDADDR Fa "struct pfioc_pooladdr"
102 to the buffer address pool to be used in the following
103 DIOCADDRULE or DIOCCHANGERULE call.
104 All other members of the structure are ignored.
105 .It Dv DIOCADDRULE Fa "struct pfioc_rule"
110 u_int32_t pool_ticket;
112 char anchor[PF_ANCHOR_NAME_SIZE];
113 char ruleset[PF_RULESET_NAME_SIZE];
120 at the end of the inactive ruleset.
123 obtained through preceding DIOCXBEGIN call, and
125 obtained through DIOCBEGINADDRS call.
126 DIOCADDADDR must also be called if any pool addresses are required.
131 names indicate the anchor and ruleset in which to append the rule.
136 .It Dv DIOCADDALTQ Fa "struct pfioc_altq"
146 .It Dv DIOCGETRULES Fa "struct pfioc_rule"
149 for subsequent DIOCGETRULE calls and
151 of rules in the active ruleset.
152 .It Dv DIOCGETRULE Fa "struct pfioc_rule"
159 obtained through a preceding DIOCGETRULES call.
160 .It Dv DIOCGETADDRS Fa "struct pfioc_pooladdr"
163 for subsequent DIOCGETADDR calls and
165 of pool addresses in the rule specified with
171 .It Dv DIOCGETADDR Fa "struct pfioc_pooladdr"
176 from the rule specified with
184 obtained through a preceding DIOCGETADDRS call.
185 .It Dv DIOCGETALTQS Fa "struct pfioc_altq"
188 for subsequent DIOCGETALTQ calls and
190 of queues in the active list.
191 .It Dv DIOCGETALTQ Fa "struct pfioc_altq"
198 obtained through a preceding DIOCGETALTQS call.
199 .It Dv DIOCGETQSTATS Fa "struct pfioc_qstats"
200 Returns statistics on a queue.
202 struct pfioc_qstats {
211 A pointer to a buffer of statistics
215 for the queue specified by
217 .It Dv DIOCADDSTATE Fa "struct pfioc_state"
219 .It Dv DIOCGETSTATE Fa "struct pfioc_state"
223 struct pf_state state;
227 Extracts the entry with the specified number from the state table.
228 .It Dv DIOCKILLSTATES Fa "struct pfioc_state_kill"
229 Removes matching entries from the state table.
230 Returns the number of killed states in psk_af.
232 struct pfioc_state_kill {
235 struct pf_rule_addr psk_src;
236 struct pf_rule_addr psk_dst;
237 char psk_ifname[IFNAMSIZ];
240 .It Dv DIOCCLRSTATES Fa "struct pfioc_state_kill"
244 but ignores the psk_af, psk_proto, psk_src and psk_dst fields of the
247 .It Dv DIOCSETSTATUSIF Fa "struct pfioc_if"
250 char ifname[IFNAMSIZ];
254 Specifies the interface for which statistics are accumulated.
255 .It Dv DIOCGETSTATUS Fa "struct pf_status"
258 u_int64_t counters[PFRES_MAX];
259 u_int64_t fcounters[FCNT_MAX];
260 u_int64_t scounters[SCNT_MAX];
261 u_int64_t pcounters[2][2][3];
262 u_int64_t bcounters[2][2];
270 char ifname[IFNAMSIZ];
274 Gets the internal packet filter statistics.
276 Clears the internal packet filter statistics.
277 .It Dv DIOCNATLOOK Fa "struct pfioc_natlook"
278 Looks up a state table entry by source and destination addresses and ports.
280 struct pfioc_natlook {
281 struct pf_addr saddr;
282 struct pf_addr daddr;
283 struct pf_addr rsaddr;
284 struct pf_addr rdaddr;
294 .It Dv DIOCSETDEBUG Fa "u_int32_t"
295 Sets the debug level.
297 enum { PF_DEBUG_NONE=0, PF_DEBUG_URGENT=1, PF_DEBUG_MISC=2 };
299 .It Dv DIOCGETSTATES Fa "struct pfioc_states"
301 struct pfioc_states {
305 struct pf_state *psu_states;
307 #define ps_buf ps_u.psu_buf
308 #define ps_states ps_u.psu_states
311 .It Dv DIOCCHANGERULE Fa "struct pfioc_rule"
314 in the ruleset specified by
317 enum { PF_CHANGE_ADD_HEAD=1, PF_CHANGE_ADD_TAIL=2,
318 PF_CHANGE_ADD_BEFORE=3, PF_CHANGE_ADD_AFTER=4,
319 PF_CHANGE_REMOVE=5, PF_CHANGE_GET_TICKET=6 };
322 The type of operation to be performed is indicated by
326 must be set to the value obtained with PF_CHANGE_GET_TICKET
327 for all actions except PF_CHANGE_GET_TICKET.
329 must be set to the value obtained with the DIOCBEGINADDRS call
330 for all actions except PF_CHANGE_REMOVE and PF_CHANGE_GET_TICKET.
335 indicate which anchor and ruleset the operation applies to.
337 indicates the rule number against which PF_CHANGE_ADD_BEFORE,
338 PF_CHANGE_ADD_AFTER or PF_CHANGE_REMOVE actions are applied.
339 .It Dv DIOCCHANGEADDR Fa "struct pfioc_pooladdr"
340 Adds or removes a pool address
342 from a rule specified with
348 .It Dv DIOCSETTIMEOUT Fa "struct pfioc_tm"
355 .It Dv DIOCGETTIMEOUT Fa "struct pfioc_tm"
356 .It Dv DIOCCLRRULECTRS
357 Clear per-rule statistics.
358 .It Dv DIOCSETLIMIT Fa "struct pfioc_limit"
359 Sets hard limits on the memory pools used by the packet filter.
366 .It Dv DIOCGETLIMIT Fa "struct pfioc_limit"
367 .It Dv DIOCRCLRTABLES Fa "struct pfioc_table"
369 All the IOCTLs that manipulate radix tables
370 use the same structure described below.
372 .Dv DIOCRCLRTABLES, pfrio_ndel contains on exit the number
376 struct pfr_table pfrio_table;
387 #define pfrio_exists pfrio_nadd
388 #define pfrio_nzero pfrio_nadd
389 #define pfrio_nmatch pfrio_nadd
390 #define pfrio_naddr pfrio_size2
391 #define pfrio_setflag pfrio_size2
392 #define pfrio_clrflag pfrio_nadd
394 .It Dv DIOCRADDTABLES Fa "struct pfioc_table"
395 Creates one or more tables.
396 On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
397 On exit, pfrio_nadd contains the number of tables effectively created.
400 char pfrt_anchor[PF_ANCHOR_NAME_SIZE];
401 char pfrt_ruleset[PF_RULESET_NAME_SIZE];
402 char pfrt_name[PF_TABLE_NAME_SIZE];
403 u_int32_t pfrt_flags;
407 .It Dv DIOCRDELTABLES Fa "struct pfioc_table"
408 Deletes one or more tables.
409 On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
410 On exit, pfrio_nadd contains the number of tables effectively deleted.
411 .It Dv DIOCRGETTABLES Fa "struct pfioc_table"
412 Get the list of all tables.
413 On entry, pfrio_buffer[pfrio_size] contains a valid writeable buffer for
414 pfr_table structures.
415 On exit, pfrio_size contains the number of tables written into the buffer.
416 If the buffer is too small, the kernel does not store anything but just
417 returns the required buffer size, without error.
418 .It Dv DIOCRGETTSTATS Fa "struct pfioc_table"
421 but returns an array of pfr_tstats structures.
424 struct pfr_table pfrts_t;
425 u_int64_t pfrts_packets
426 [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
427 u_int64_t pfrts_bytes
428 [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
429 u_int64_t pfrts_match;
430 u_int64_t pfrts_nomatch;
433 int pfrts_refcnt[PFR_REFCNT_MAX];
435 #define pfrts_name pfrts_t.pfrt_name
436 #define pfrts_flags pfrts_t.pfrt_flags
438 .It Dv DIOCRCLRTSTATS Fa "struct pfioc_table"
439 Clears the statistics of one or more tables.
440 On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
441 On exit, pfrio_nzero contains the number of tables effectively cleared.
442 .It Dv DIOCRCLRADDRS Fa "struct pfioc_table"
443 Clear all addresses in a table.
444 On entry, pfrio_table contains the table to clear.
445 On exit, pfrio_ndel contains the number of addresses removed.
446 .It Dv DIOCRADDADDRS Fa "struct pfioc_table"
447 Add one or more addresses to a table.
448 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
449 contains the list of pfr_addr structures to add.
450 On exit, pfrio_nadd contains the number of addresses effectively added.
454 struct in_addr _pfra_ip4addr;
455 struct in6_addr _pfra_ip6addr;
462 #define pfra_ip4addr pfra_u._pfra_ip4addr
463 #define pfra_ip6addr pfra_u._pfra_ip6addr
465 .It Dv DIOCRDELADDRS Fa "struct pfioc_table"
466 Delete one or more addresses from a table.
467 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
468 contains the list of pfr_addr structures to delete.
469 On exit, pfrio_ndel contains the number of addresses effectively deleted.
470 .It Dv DIOCRSETADDRS Fa "struct pfioc_table"
471 Replace the content of a table by a new address list.
472 This is the most complicated command, which uses all the structure members.
473 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
474 contains the new list of pfr_addr structures.
475 In addition to that, if size2 is nonzero, pfrio_buffer[pfrio_size..pfrio_size2]
476 must be a writeable buffer, into which the kernel can copy the addresses that
477 have been deleted during the replace operation.
478 On exit, pfrio_ndel, pfrio_nadd and pfrio_nchange contain the number of
479 addresses deleted, added and changed by the kernel.
480 If pfrio_size2 was set on
481 entry, pfrio_size2 will point to the size of the buffer used, exactly like
483 .It Dv DIOCRGETADDRS Fa "struct pfioc_table"
484 Get all the addresses of a table.
485 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
486 contains a valid writeable buffer for pfr_addr structures.
487 On exit, pfrio_size contains the number of addresses written into the buffer.
488 If the buffer was too small, the kernel does not store anything but just
489 return the required buffer size, without returning an error.
490 .It Dv DIOCRGETASTATS Fa "struct pfioc_table"
493 but returns an array of pfr_astats structures.
496 struct pfr_addr pfras_a;
497 u_int64_t pfras_packets
498 [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
499 u_int64_t pfras_bytes
500 [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
504 .It Dv DIOCRCLRASTATS Fa "struct pfioc_table"
505 Clears the statistics of one or more addresses.
506 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
507 contains a table of pfr_addr structures to clear.
508 On exit, pfrio_nzero contains the number of addresses effectively cleared.
509 .It Dv DIOCRTSTADDRS Fa "struct pfioc_table"
510 Test if the given addresses match a table.
511 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
512 contains a table of pfr_addr structures to test.
513 On exit, the kernel updates the pfr_addr table by setting the pfra_fback
514 member appropriately.
515 .It Dv DIOCRSETTFLAGS Fa "struct pfioc_table"
521 On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures,
522 and pfrio_setflag contains the flags to add, while pfrio_clrflag contains the
524 On exit, pfrio_nchange and pfrio_ndel contain the number of tables altered
525 or deleted by the kernel.
526 Yes, tables can be deleted if one removes the
528 flag of an unreferenced table.
529 .It Dv DIOCRINADEFINE Fa "struct pfioc_table"
530 Defines a table in the inactive set.
531 On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
532 contains the list of pfr_addr structures to put in the table.
533 A valid ticket must also be supplied to pfrio_ticket.
534 On exit, pfrio_nadd contains 0 if the table was already defined in the
535 inactive list, or 1 if a new table has been created.
536 pfrio_naddr contains the number of addresses effectively put in the table.
537 .It Dv DIOCXBEGIN Fa "struct pfioc_trans"
539 #define PF_RULESET_ALTQ (PF_RULESET_MAX)
540 #define PF_RULESET_TABLE (PF_RULESET_MAX+1)
542 int size; /* number of elements */
543 int esize; /* size of each element in bytes */
544 struct pfioc_trans_e {
546 char anchor[PF_ANCHOR_NAME_SIZE];
547 char ruleset[PF_RULESET_NAME_SIZE];
553 Clears all the inactive rulesets specified in the
554 .Fa "struct pfioc_trans_e"
556 For each ruleset, a ticket is returned for subsequent "add rule" IOCTLs,
562 .It Dv DIOCXCOMMIT Fa "struct pfioc_trans"
563 Atomically switch a vector of inactive rulesets to the active rulesets.
564 Implemented as a standard 2-phase commit, which will either fail for all
565 rulesets or completely succeed.
566 All tickets need to be valid.
569 if a concurrent process is trying to update some of the same rulesets
571 .It Dv DIOCXROLLBACK Fa "struct pfioc_trans"
572 Clean up the kernel by undoing all changes that have taken place on the
573 inactive rulesets since the last
576 will silently ignore rulesets for which the ticket is invalid.
578 Flush the passive OS fingerprint table.
579 .It Dv DIOCFPADD Fa "struct pf_osfp_ioctl"
581 struct pf_osfp_ioctl {
582 struct pf_osfp_entry {
583 SLIST_ENTRY(pf_osfp_entry) fp_entry;
585 char fp_class_nm[PF_OSFP_LEN];
586 char fp_version_nm[PF_OSFP_LEN];
587 char fp_subtype_nm[PF_OSFP_LEN];
599 Add a passive OS fingerprint to the table.
602 to the packed fingerprint,
603 .Va fp_os.fp_class_nm
604 to the name of the class (Linux, Windows, etc),
605 .Va fp_os.fp_version_nm
606 to the name of the version (NT, 95, 98), and
607 .Va fp_os.fp_subtype_nm
608 to the name of the subtype or patchlevel.
616 are set to the TCP MSS, the TCP window size, the IP length and the IP TTL of
617 the TCP SYN packet respectively.
620 member is filled according to the net/pfvar.h include file PF_OSFP_* defines.
623 is not used with this ioctl.
625 The structure's slack space must be zeroed for correct operation; memset
626 the whole structure to zero before filling and sending to the kernel.
627 .It Dv DIOCFPGET Fa "struct pf_osfp_ioctl"
629 struct pf_osfp_ioctl {
630 struct pf_osfp_entry {
631 SLIST_ENTRY(pf_osfp_entry) fp_entry;
633 char fp_class_nm[PF_OSFP_LEN];
634 char fp_version_nm[PF_OSFP_LEN];
635 char fp_subtype_nm[PF_OSFP_LEN];
647 Get the passive OS fingerprint number
649 from the kernel's fingerprint list.
650 The rest of the structure members will come back filled.
651 Get the whole list by repeatedly incrementing the
653 number until the ioctl returns EBUSY.
654 .It Dv DIOCGETSRCNODES Fa "struct pfioc_src_nodes"
656 struct pfioc_src_nodes {
660 struct pf_src_node *psu_src_nodes;
662 #define psn_buf psn_u.psu_buf
663 #define psn_src_nodes psn_u.psu_src_nodes
667 Get the list of source nodes kept by the
672 The ioctl must be called once with
675 If the ioctl returns without error,
677 will be set to the size of the buffer required to hold all the
679 structures held in the table.
680 A buffer of this size should then be allocated, and a pointer to this buffer
683 The ioctl must then be called again to fill this buffer with the actual
687 will be set to the length of the buffer actually used.
688 .It Dv DIOCCLRSRCNODES Fa "struct pfioc_table"
689 Clear the tree of source tracking nodes.
690 .It Dv DIOCIGETIFACES Fa "struct pfioc_iface"
691 Gets the list of interfaces and interface drivers known to
693 All the IOCTLs that manipulate interfaces
694 use the same structure described below:
697 char pfiio_name[IFNAMSIZ];
705 #define PFI_FLAG_GROUP 0x0001 /* gets groups of interfaces */
706 #define PFI_FLAG_INSTANCE 0x0002 /* gets single interfaces */
707 #define PFI_FLAG_ALLMASK 0x0003
712 can be used to restrict the search to a specific interface or driver.
713 .Va pfiio_buffer[pfiio_size]
714 is the user-supplied buffer for returning the data.
717 represents the number of
719 entries that can fit into the buffer.
720 The kernel will replace this value by the real number of entries it wants
723 should be set to sizeof(struct pfi_if).
726 .Dv PFI_FLAG_GROUP , PFI_FLAG_INSTANCE ,
727 or both to tell the kernel to return a group of interfaces
728 (drivers, like "fxp"), real interface instances (like "fxp1") or both.
729 The data is returned in the
731 structure described below:
734 char pfif_name[IFNAMSIZ];
735 u_int64_t pfif_packets[2][2][2];
736 u_int64_t pfif_bytes[2][2][2];
737 u_int64_t pfif_addcnt;
738 u_int64_t pfif_delcnt;
745 #define PFI_IFLAG_GROUP 0x0001 /* group of interfaces */
746 #define PFI_IFLAG_INSTANCE 0x0002 /* single instance */
747 #define PFI_IFLAG_CLONABLE 0x0010 /* clonable group */
748 #define PFI_IFLAG_DYNAMIC 0x0020 /* dynamic group */
749 #define PFI_IFLAG_ATTACHED 0x0040 /* interface attached */
750 #define PFI_IFLAG_REFERENCED 0x0080 /* referenced by rules */
752 .It Dv DIOCICLRISTATS Fa "struct pfioc_iface"
753 Clear the statistics counters of one or more interfaces.
757 can be used to select which interfaces need to be cleared.
758 The filtering process is the same as for
761 will be set by the kernel to the number of interfaces and drivers
762 that have been cleared.
765 The following example demonstrates how to use the DIOCNATLOOK command
766 to find the internal host/port of a NATed connection.
768 #include <sys/types.h>
769 #include <sys/socket.h>
770 #include <sys/ioctl.h>
771 #include <sys/fcntl.h>
773 #include <netinet/in.h>
774 #include <net/pfvar.h>
780 read_address(const char *s)
784 sscanf(s, "%i.%i.%i.%i", &a, &b, &c, &d);
785 return htonl(a << 24 | b << 16 | c << 8 | d);
789 print_address(u_int32_t a)
792 printf("%d.%d.%d.%d", a >> 24 & 255, a >> 16 & 255,
793 a >> 8 & 255, a & 255);
797 main(int argc, char *argv[])
799 struct pfioc_natlook nl;
803 printf("%s <gwy addr> <gwy port> <ext addr> <ext port>\\n",
808 dev = open("/dev/pf", O_RDWR);
810 err(1, "open(\\"/dev/pf\\") failed");
812 memset(&nl, 0, sizeof(struct pfioc_natlook));
813 nl.saddr.v4.s_addr = read_address(argv[1]);
814 nl.sport = htons(atoi(argv[2]));
815 nl.daddr.v4.s_addr = read_address(argv[3]);
816 nl.dport = htons(atoi(argv[4]));
818 nl.proto = IPPROTO_TCP;
819 nl.direction = PF_IN;
821 if (ioctl(dev, DIOCNATLOOK, &nl))
822 err(1, "DIOCNATLOOK");
824 printf("internal host ");
825 print_address(nl.rsaddr.v4.s_addr);
826 printf(":%u\\n", ntohs(nl.rsport));
839 packet filtering mechanism first appeared in