FreeBSD Man Pages

pf(4)

NAME

     pf -- packet filter

SYNOPSIS

     device pf

DESCRIPTION

     Packet filtering takes place in the kernel.  A pseudo-device, /dev/pf,
     allows userland processes to control the behavior of the packet filter
     through an ioctl(2) interface.  There are commands to enable and disable
     the filter, load rulesets, add and remove individual rules or state table
     entries, and retrieve statistics.	The most commonly used functions are
     covered by pfctl(8).

     Manipulations like loading a ruleset that involve more than a single
     ioctl call require a so-called ticket, which prevents the occurrence of
     multiple concurrent manipulations.

     Fields of ioctl parameter structures that refer to packet data (like
     addresses and ports) are generally expected in network byte-order.

FILES

     /dev/pf  packet filtering device.

IOCTL INTERFACE

     pf supports the following ioctl(2) commands:

     DIOCSTART
	     Starts the packet filter.

     DIOCSTOP
	     Stops the packet filter.

     DIOCSTARTALTQ
	     Starts the ALTQ bandwidth control system.

     DIOCSTOPALTQ
	     Stops the ALTQ bandwidth control system.

     DIOCBEGINADDRS struct pfioc_pooladdr

	     struct pfioc_pooladdr {
		     u_int32_t		     action;
		     u_int32_t		     ticket;
		     u_int32_t		     nr;
		     u_int32_t		     r_num;
		     u_int8_t		     r_action;
		     u_int8_t		     r_last;
		     u_int8_t		     af;
		     char		     anchor[PF_ANCHOR_NAME_SIZE];
		     char		     ruleset[PF_RULESET_NAME_SIZE];
		     struct pf_pooladdr      addr;
	     };

	     Clears the buffer address pool and returns a ticket for subse-
	     quent DIOCADDADDR, DIOCADDRULE and DIOCCHANGERULE calls.

	     struct pfioc_rule {
		     u_int32_t	     action;
		     u_int32_t	     ticket;
		     u_int32_t	     pool_ticket;
		     u_int32_t	     nr;
		     char	     anchor[PF_ANCHOR_NAME_SIZE];
		     char	     ruleset[PF_RULESET_NAME_SIZE];
		     struct pf_rule  rule;
	     };

	     Adds rule at the end of the inactive ruleset.  Requires ticket
	     obtained through preceding DIOCXBEGIN call, and pool_ticket
	     obtained through DIOCBEGINADDRS call.  DIOCADDADDR must also be
	     called if any pool addresses are required.  The optional anchor
	     and ruleset names indicate the anchor and ruleset in which to
	     append the rule.  nr and action are ignored.

     DIOCADDALTQ struct pfioc_altq
	     Adds

	     struct pfioc_altq {
		     u_int32_t	     action;
		     u_int32_t	     ticket;
		     u_int32_t	     nr;
		     struct pf_altq   altq;
	     };

     DIOCGETRULES struct pfioc_rule
	     Returns ticket for subsequent DIOCGETRULE calls and nr of rules
	     in the active ruleset.

     DIOCGETRULE struct pfioc_rule
	     Returns rule number nr using ticket obtained through a preceding
	     DIOCGETRULES call.

     DIOCGETADDRS struct pfioc_pooladdr
	     Returns ticket for subsequent DIOCGETADDR calls and nr of pool
	     addresses in the rule specified with r_action, r_num, anchor and
	     ruleset.

     DIOCGETADDR struct pfioc_pooladdr
	     Returns pool address addr number nr from the rule specified with
	     r_action, r_num, anchor and ruleset using ticket obtained through
	     a preceding DIOCGETADDRS call.

     DIOCGETALTQS struct pfioc_altq
	     Returns ticket for subsequent DIOCGETALTQ calls and nr of queues
	     in the active list.

     DIOCGETALTQ struct pfioc_altq
	     Returns altq number nr using ticket obtained through a preceding
	     DIOCGETALTQS call.

     DIOCGETQSTATS struct pfioc_qstats
	     Returns statistics on a queue.

	     struct pfioc_qstats {
		     u_int32_t	      ticket;

     DIOCADDSTATE struct pfioc_state
	     Adds a state entry.

     DIOCGETSTATE struct pfioc_state

	     struct pfioc_state {
		     u_int32_t	      nr;
		     struct pf_state  state;
	     };

	     Extracts the entry with the specified number from the state ta-
	     ble.

     DIOCKILLSTATES struct pfioc_state_kill
	     Removes matching entries from the state table.  Returns the num-
	     ber of killed states in psk_af.

	     struct pfioc_state_kill {
		     int		     psk_af;
		     int		     psk_proto;
		     struct pf_rule_addr     psk_src;
		     struct pf_rule_addr     psk_dst;
		     char		     psk_ifname[IFNAMSIZ];
	     };

     DIOCCLRSTATES struct pfioc_state_kill
	     Clears all states.  It works like DIOCKILLSTATES, but ignores the
	     psk_af, psk_proto, psk_src and psk_dst fields of the
	     pfioc_state_kill structure.

     DIOCSETSTATUSIF struct pfioc_if

	     struct pfioc_if {
		     char	      ifname[IFNAMSIZ];
	     };

	     Specifies the interface for which statistics are accumulated.

     DIOCGETSTATUS struct pf_status

	     struct pf_status {
		     u_int64_t	     counters[PFRES_MAX];
		     u_int64_t	     fcounters[FCNT_MAX];
		     u_int64_t	     scounters[SCNT_MAX];
		     u_int64_t	     pcounters[2][2][3];
		     u_int64_t	     bcounters[2][2];
		     u_int64_t	     stateid;
		     u_int32_t	     running;
		     u_int32_t	     states;
		     u_int32_t	     src_nodes;
		     u_int32_t	     since;
		     u_int32_t	     debug;
		     u_int32_t	     hostid;
		     char	     ifname[IFNAMSIZ];
	     };

	     Gets the internal packet filter statistics.
	     struct pfioc_natlook {
		     struct pf_addr   saddr;
		     struct pf_addr   daddr;
		     struct pf_addr   rsaddr;
		     struct pf_addr   rdaddr;
		     u_int16_t	      sport;
		     u_int16_t	      dport;
		     u_int16_t	      rsport;
		     u_int16_t	      rdport;
		     sa_family_t      af;
		     u_int8_t	      proto;
		     u_int8_t	      direction;
	     };

     DIOCSETDEBUG u_int32_t
	     Sets the debug level.

	     enum    { PF_DEBUG_NONE=0, PF_DEBUG_URGENT=1, PF_DEBUG_MISC=2 };

     DIOCGETSTATES struct pfioc_states

	     struct pfioc_states {
		     int     ps_len;
		     union {
			     caddr_t psu_buf;
			     struct pf_state *psu_states;
		     } ps_u;
	     #define ps_buf	     ps_u.psu_buf
	     #define ps_states	     ps_u.psu_states
	     };

     DIOCCHANGERULE struct pfioc_rule
	     Adds or removes the rule in the ruleset specified by rule.action.

	     enum    { PF_CHANGE_ADD_HEAD=1, PF_CHANGE_ADD_TAIL=2,
		       PF_CHANGE_ADD_BEFORE=3, PF_CHANGE_ADD_AFTER=4,
		       PF_CHANGE_REMOVE=5, PF_CHANGE_GET_TICKET=6 };

	     The type of operation to be performed is indicated by action.

	     ticket must be set to the value obtained with
	     PF_CHANGE_GET_TICKET for all actions except PF_CHANGE_GET_TICKET.
	     pool_ticket must be set to the value obtained with the DIOCBEGI-
	     NADDRS call for all actions except PF_CHANGE_REMOVE and
	     PF_CHANGE_GET_TICKET.

	     anchor and ruleset indicate which anchor and ruleset the opera-
	     tion applies to.  nr indicates the rule number against which
	     PF_CHANGE_ADD_BEFORE, PF_CHANGE_ADD_AFTER or PF_CHANGE_REMOVE
	     actions are applied.

     DIOCCHANGEADDR struct pfioc_pooladdr
	     Adds or removes a pool address addr from a rule specified with
	     r_action, r_num, anchor and ruleset.

     DIOCSETTIMEOUT struct pfioc_tm

	     struct pfioc_tm {

     DIOCSETLIMIT struct pfioc_limit
	     Sets hard limits on the memory pools used by the packet filter.

	     struct pfioc_limit {
		     int	     index;
		     unsigned	     limit;
	     };

     DIOCGETLIMIT struct pfioc_limit

     DIOCRCLRTABLES struct pfioc_table
	     Clear all tables.	All the IOCTLs that manipulate radix tables
	     use the same structure described below.  For DIOCRCLRTABLES,
	     pfrio_ndel contains on exit the number of tables deleted.

	     struct pfioc_table {
		     struct pfr_table	      pfrio_table;
		     void		     *pfrio_buffer;
		     int		      pfrio_esize;
		     int		      pfrio_size;
		     int		      pfrio_size2;
		     int		      pfrio_nadd;
		     int		      pfrio_ndel;
		     int		      pfrio_nchange;
		     int		      pfrio_flags;
		     int		      pfrio_ticket;
	     };
	     #define pfrio_exists    pfrio_nadd
	     #define pfrio_nzero     pfrio_nadd
	     #define pfrio_nmatch    pfrio_nadd
	     #define pfrio_naddr     pfrio_size2
	     #define pfrio_setflag   pfrio_size2
	     #define pfrio_clrflag   pfrio_nadd

     DIOCRADDTABLES struct pfioc_table
	     Creates one or more tables.  On entry, pfrio_buffer[pfrio_size]
	     contains a table of pfr_table structures.	On exit, pfrio_nadd
	     contains the number of tables effectively created.

	     struct pfr_table {
		     char		      pfrt_anchor[PF_ANCHOR_NAME_SIZE];
		     char		      pfrt_ruleset[PF_RULESET_NAME_SIZE];
		     char		      pfrt_name[PF_TABLE_NAME_SIZE];
		     u_int32_t		      pfrt_flags;
		     u_int8_t		      pfrt_fback;
	     };

     DIOCRDELTABLES struct pfioc_table
	     Deletes one or more tables.  On entry, pfrio_buffer[pfrio_size]
	     contains a table of pfr_table structures.	On exit, pfrio_nadd
	     contains the number of tables effectively deleted.

     DIOCRGETTABLES struct pfioc_table
	     Get the list of all tables.  On entry, pfrio_buffer[pfrio_size]
	     contains a valid writeable buffer for pfr_table structures.  On
	     exit, pfrio_size contains the number of tables written into the
	     buffer.  If the buffer is too small, the kernel does not store
		     struct pfr_table pfrts_t;
		     u_int64_t	      pfrts_packets
					  [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
		     u_int64_t	      pfrts_bytes
					  [PFR_DIR_MAX][PFR_OP_TABLE_MAX];
		     u_int64_t	      pfrts_match;
		     u_int64_t	      pfrts_nomatch;
		     long	      pfrts_tzero;
		     int	      pfrts_cnt;
		     int	      pfrts_refcnt[PFR_REFCNT_MAX];
	     };
	     #define pfrts_name      pfrts_t.pfrt_name
	     #define pfrts_flags     pfrts_t.pfrt_flags

     DIOCRCLRTSTATS struct pfioc_table
	     Clears the statistics of one or more tables.  On entry,
	     pfrio_buffer[pfrio_size] contains a table of pfr_table struc-
	     tures.  On exit, pfrio_nzero contains the number of tables effec-
	     tively cleared.

     DIOCRCLRADDRS struct pfioc_table
	     Clear all addresses in a table.  On entry, pfrio_table contains
	     the table to clear.  On exit, pfrio_ndel contains the number of
	     addresses removed.

     DIOCRADDADDRS struct pfioc_table
	     Add one or more addresses to a table.  On entry, pfrio_table con-
	     tains the table id and pfrio_buffer[pfrio_size] contains the list
	     of pfr_addr structures to add.  On exit, pfrio_nadd contains the
	     number of addresses effectively added.

	     struct pfr_addr {
		     union {
			     struct in_addr   _pfra_ip4addr;
			     struct in6_addr  _pfra_ip6addr;
		     }		      pfra_u;
		     u_int8_t	      pfra_af;
		     u_int8_t	      pfra_net;
		     u_int8_t	      pfra_not;
		     u_int8_t	      pfra_fback;
	     };
	     #define pfra_ip4addr    pfra_u._pfra_ip4addr
	     #define pfra_ip6addr    pfra_u._pfra_ip6addr

     DIOCRDELADDRS struct pfioc_table
	     Delete one or more addresses from a table.  On entry, pfrio_table
	     contains the table id and pfrio_buffer[pfrio_size] contains the
	     list of pfr_addr structures to delete.  On exit, pfrio_ndel con-
	     tains the number of addresses effectively deleted.

     DIOCRSETADDRS struct pfioc_table
	     Replace the content of a table by a new address list.  This is
	     the most complicated command, which uses all the structure mem-
	     bers.  On entry, pfrio_table contains the table id and
	     pfrio_buffer[pfrio_size] contains the new list of pfr_addr struc-
	     tures.  In addition to that, if size2 is nonzero,
	     pfrio_buffer[pfrio_size..pfrio_size2] must be a writeable buffer,
	     into which the kernel can copy the addresses that have been
	     the table id and pfrio_buffer[pfrio_size] contains a valid write-
	     able buffer for pfr_addr structures.  On exit, pfrio_size con-
	     tains the number of addresses written into the buffer.  If the
	     buffer was too small, the kernel does not store anything but just
	     return the required buffer size, without returning an error.

     DIOCRGETASTATS struct pfioc_table
	     Like DIOCRGETADDRS, but returns an array of pfr_astats struc-
	     tures.

	     struct pfr_astats {
		     struct pfr_addr  pfras_a;
		     u_int64_t	      pfras_packets
					  [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
		     u_int64_t	      pfras_bytes
					  [PFR_DIR_MAX][PFR_OP_ADDR_MAX];
		     long	      pfras_tzero;
	     };

     DIOCRCLRASTATS struct pfioc_table
	     Clears the statistics of one or more addresses.  On entry,
	     pfrio_table contains the table id and pfrio_buffer[pfrio_size]
	     contains a table of pfr_addr structures to clear.	On exit,
	     pfrio_nzero contains the number of addresses effectively cleared.

     DIOCRTSTADDRS struct pfioc_table
	     Test if the given addresses match a table.  On entry, pfrio_table
	     contains the table id and pfrio_buffer[pfrio_size] contains a ta-
	     ble of pfr_addr structures to test.  On exit, the kernel updates
	     the pfr_addr table by setting the pfra_fback member appropri-
	     ately.

     DIOCRSETTFLAGS struct pfioc_table
	     Change the const or persist flag of a table.  On entry,
	     pfrio_buffer[pfrio_size] contains a table of pfr_table struc-
	     tures, and pfrio_setflag contains the flags to add, while
	     pfrio_clrflag contains the flags to remove.  On exit,
	     pfrio_nchange and pfrio_ndel contain the number of tables altered
	     or deleted by the kernel.	Yes, tables can be deleted if one
	     removes the persist flag of an unreferenced table.

     DIOCRINADEFINE struct pfioc_table
	     Defines a table in the inactive set.  On entry, pfrio_table con-
	     tains the table id and pfrio_buffer[pfrio_size] contains the list
	     of pfr_addr structures to put in the table.  A valid ticket must
	     also be supplied to pfrio_ticket.	On exit, pfrio_nadd contains 0
	     if the table was already defined in the inactive list, or 1 if a
	     new table has been created.  pfrio_naddr contains the number of
	     addresses effectively put in the table.

     DIOCXBEGIN struct pfioc_trans

	     #define PF_RULESET_ALTQ	     (PF_RULESET_MAX)
	     #define PF_RULESET_TABLE	     (PF_RULESET_MAX+1)
	     struct pfioc_trans {
		     int	      size;  /* number of elements */
		     int	      esize; /* size of each element in bytes */
		     struct pfioc_trans_e {

	     pfioc_trans_e array.  For each ruleset, a ticket is returned for
	     subsequent "add rule" IOCTLs, as well as for the DIOCXCOMMIT and
	     DIOCXROLLBACK calls.

     DIOCXCOMMIT struct pfioc_trans
	     Atomically switch a vector of inactive rulesets to the active
	     rulesets.	Implemented as a standard 2-phase commit, which will
	     either fail for all rulesets or completely succeed.  All tickets
	     need to be valid.	Returns EBUSY if a concurrent process is try-
	     ing to update some of the same rulesets concurrently.

     DIOCXROLLBACK struct pfioc_trans
	     Clean up the kernel by undoing all changes that have taken place
	     on the inactive rulesets since the last DIOCXBEGIN.
	     DIOCXROLLBACK will silently ignore rulesets for which the ticket
	     is invalid.

     DIOCFPFLUSH
	     Flush the passive OS fingerprint table.

     DIOCFPADD struct pf_osfp_ioctl

	     struct pf_osfp_ioctl {
		     struct pf_osfp_entry {
			     SLIST_ENTRY(pf_osfp_entry) fp_entry;
			     pf_osfp_t		     fp_os;
			     char		     fp_class_nm[PF_OSFP_LEN];
			     char		     fp_version_nm[PF_OSFP_LEN];
			     char		     fp_subtype_nm[PF_OSFP_LEN];
		     }			     fp_os;
		     u_int16_t		     fp_mss;
		     u_int16_t		     fp_wsize;
		     u_int16_t		     fp_psize;
		     u_int8_t		     fp_ttl;
		     u_int8_t		     fp_wscale;
		     u_int8_t		     fp_flags;
		     int		     fp_getnum;
	     };

	     Add a passive OS fingerprint to the table.  Set fp_os.fp_os to
	     the packed fingerprint, fp_os.fp_class_nm to the name of the
	     class (Linux, Windows, etc), fp_os.fp_version_nm to the name of
	     the version (NT, 95, 98), and fp_os.fp_subtype_nm to the name of
	     the subtype or patchlevel.  The members fp_mss, fp_wsize,
	     fp_psize, fp_ttl, and fp_wscale are set to the TCP MSS, the TCP
	     window size, the IP length and the IP TTL of the TCP SYN packet
	     respectively.  The fp_flags member is filled according to the
	     net/pfvar.h include file PF_OSFP_* defines.  The fp_getnum is not
	     used with this ioctl.

	     The structure's slack space must be zeroed for correct operation;
	     memset the whole structure to zero before filling and sending to
	     the kernel.

     DIOCFPGET struct pf_osfp_ioctl

	     struct pf_osfp_ioctl {
		     struct pf_osfp_entry {
		     u_int16_t		     fp_psize;
		     u_int8_t		     fp_ttl;
		     u_int8_t		     fp_wscale;
		     u_int8_t		     fp_flags;
		     int		     fp_getnum;
	     };

	     Get the passive OS fingerprint number fp_getnum from the kernel's
	     fingerprint list.	The rest of the structure members will come
	     back filled.  Get the whole list by repeatedly incrementing the
	     fp_getnum number until the ioctl returns EBUSY.

     DIOCGETSRCNODES struct pfioc_src_nodes

	     struct pfioc_src_nodes {
		     int     psn_len;
		     union {
			     caddr_t	      psu_buf;
			     struct pf_src_node      *psu_src_nodes;
		     } psn_u;
	     #define psn_buf	     psn_u.psu_buf
	     #define psn_src_nodes   psn_u.psu_src_nodes
	     };

	     Get the list of source nodes kept by the sticky-address and
	     source-track options.  The ioctl must be called once with psn_len
	     set to 0.	If the ioctl returns without error, psn_len will be
	     set to the size of the buffer required to hold all the
	     pf_src_node structures held in the table.	A buffer of this size
	     should then be allocated, and a pointer to this buffer placed in
	     psn_buf.  The ioctl must then be called again to fill this buffer
	     with the actual source node data.	After the ioctl call psn_len
	     will be set to the length of the buffer actually used.

     DIOCCLRSRCNODES struct pfioc_table
	     Clear the tree of source tracking nodes.

     DIOCIGETIFACES struct pfioc_iface
	     Gets the list of interfaces and interface drivers known to pf.
	     All the IOCTLs that manipulate interfaces use the same structure
	     described below:

	     struct pfioc_iface {
		     char		      pfiio_name[IFNAMSIZ];
		     void		     *pfiio_buffer;
		     int		      pfiio_esize;
		     int		      pfiio_size;
		     int		      pfiio_nzero;
		     int		      pfiio_flags;
	     };

	     #define PFI_FLAG_GROUP	0x0001	/* gets groups of interfaces */
	     #define PFI_FLAG_INSTANCE	0x0002	/* gets single interfaces */
	     #define PFI_FLAG_ALLMASK	0x0003

	     If not empty, pfiio_name can be used to restrict the search to a
	     specific interface or driver.  pfiio_buffer[pfiio_size] is the
	     user-supplied buffer for returning the data.  On entry,

	     struct pfi_if {
		     char			      pfif_name[IFNAMSIZ];
		     u_int64_t			      pfif_packets[2][2][2];
		     u_int64_t			      pfif_bytes[2][2][2];
		     u_int64_t			      pfif_addcnt;
		     u_int64_t			      pfif_delcnt;
		     long			      pfif_tzero;
		     int			      pfif_states;
		     int			      pfif_rules;
		     int			      pfif_flags;
	     };

	     #define PFI_IFLAG_GROUP	     0x0001  /* group of interfaces */
	     #define PFI_IFLAG_INSTANCE      0x0002  /* single instance */
	     #define PFI_IFLAG_CLONABLE      0x0010  /* clonable group */
	     #define PFI_IFLAG_DYNAMIC	     0x0020  /* dynamic group */
	     #define PFI_IFLAG_ATTACHED      0x0040  /* interface attached */
	     #define PFI_IFLAG_REFERENCED    0x0080  /* referenced by rules */

     DIOCICLRISTATS struct pfioc_iface
	     Clear the statistics counters of one or more interfaces.
	     pfiio_name and pfrio_flags can be used to select which interfaces
	     need to be cleared.  The filtering process is the same as for
	     DIOCIGETIFACES.  pfiio_nzero will be set by the kernel to the
	     number of interfaces and drivers that have been cleared.

EXAMPLES

     The following example demonstrates how to use the DIOCNATLOOK command to
     find the internal host/port of a NATed connection.

     #include <sys/types.h>
     #include <sys/socket.h>
     #include <sys/ioctl.h>
     #include <sys/fcntl.h>
     #include <net/if.h>
     #include <netinet/in.h>
     #include <net/pfvar.h>
     #include <err.h>
     #include <stdio.h>
     #include <stdlib.h>

     u_int32_t
     read_address(const char *s)
     {
	     int a, b, c, d;

	     sscanf(s, "%i.%i.%i.%i", &a, &b, &c, &d);
	     return htonl(a << 24 | b << 16 | c << 8 | d);
     }

     void
     print_address(u_int32_t a)
     {
	     a = ntohl(a);
	     printf("%d.%d.%d.%d", a >> 24 & 255, a >> 16 & 255,
		 a >> 8 & 255, a & 255);
     }
		     printf("%s <gwy addr> <gwy port> <ext addr> <ext port>\n",
			 argv[0]);
		     return 1;
	     }

	     dev = open("/dev/pf", O_RDWR);
	     if (dev == -1)
		     err(1, "open(\"/dev/pf\") failed");

	     memset(&nl, 0, sizeof(struct pfioc_natlook));
	     nl.saddr.v4.s_addr      = read_address(argv[1]);
	     nl.sport		     = htons(atoi(argv[2]));
	     nl.daddr.v4.s_addr      = read_address(argv[3]);
	     nl.dport		     = htons(atoi(argv[4]));
	     nl.af		     = AF_INET;
	     nl.proto		     = IPPROTO_TCP;
	     nl.direction	     = PF_IN;

	     if (ioctl(dev, DIOCNATLOOK, &nl))
		     err(1, "DIOCNATLOOK");

	     printf("internal host ");
	     print_address(nl.rsaddr.v4.s_addr);
	     printf(":%u\n", ntohs(nl.rsport));
	     return 0;
     }

SEE ALSO

     ioctl(2), altq(4), bridge(4), pflog(4), pfsync(4), pfctl(8)

HISTORY

     The pf packet filtering mechanism first appeared in OpenBSD 3.0.

FreeBSD 5.4		       February 7, 2005 		   FreeBSD 5.4

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