PF(4)                     OpenBSD Programmer's Manual                    PF(4)

NAME
     pf - packet filter

SYNOPSIS
     pseudo-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(2) call require a so-called ticket, which prevents the occurrence
     of multiple concurrent manipulations.

     Fields of ioctl(2) parameter structures that refer to packet data (like
     addresses and ports) are generally expected in network byte-order.

     Rules and address tables are contained in so-called anchors.  When ser-
     vicing an ioctl(2) request, if the anchor field of the argument structure
     is empty, the kernel will use the default anchor (i.e., the main ruleset)
     in operations.  Anchors are specified by name and may be nested, with
     components separated by `/' characters, similar to how file system hier-
     archies are laid out.  The final component of the anchor path is the an-
     chor under which operations will be performed.  Anchor names with charac-
     ters after the terminating null byte are considered invalid; if used in
     an ioctl, EINVAL will be returned.

IOCTL INTERFACE
     pf supports the following ioctl(2) commands, available through
     <net/pfvar.h>:

     DIOCSTART
             Start the packet filter.

     DIOCSTOP
             Stop the packet filter.

     DIOCSTARTALTQ
             Start the ALTQ bandwidth control system (see altq(9)).

     DIOCSTOPALTQ
             Stop the ALTQ bandwidth control system.

     DIOCADDRULE struct pfioc_rule *pr

             struct pfioc_rule {
                     u_int32_t       action;
                     u_int32_t       ticket;
                     u_int32_t       pool_ticket;
                     u_int32_t       nr;
                     char            anchor[MAXPATHLEN];
                     char            anchor_call[MAXPATHLEN];
                     struct pf_rule  rule;
             };

             Add rule at the end of the inactive ruleset.  This call requires
             a ticket obtained through a preceding DIOCXBEGIN call.  The op-
             tional anchor name indicates the anchor in which to append the
             rule.  nr and action are ignored.

     DIOCADDALTQ struct pfioc_altq *pa
             Add an ALTQ discipline or queue.

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

     DIOCGETRULES struct pfioc_rule *pr
             Get a ticket for subsequent DIOCGETRULE calls and the number nr
             of rules in the active ruleset.

     DIOCGETRULE struct pfioc_rule *pr
             Get a rule by its number nr using the ticket obtained through a
             preceding DIOCGETRULES call.  If action is set to
             PF_GET_CLR_CNTR, the per-rule statistics on the requested rule
             are cleared.

     DIOCGETALTQS struct pfioc_altq *pa
             Get a ticket for subsequent DIOCGETALTQ calls and the number nr
             of queues in the active list.

     DIOCGETALTQ struct pfioc_altq *pa
             Get the queueing discipline altq by its number nr using the
             ticket obtained through a preceding DIOCGETALTQS call.

     DIOCGETQSTATS struct pfioc_qstats *pq
             Get the statistics on a queue.

             struct pfioc_qstats {
                     u_int32_t        ticket;
                     u_int32_t        nr;
                     void            *buf;
                     int              nbytes;
                     u_int8_t         scheduler;
             };

             This call fills in a pointer to the buffer of statistics buf, of
             length nbytes, for the queue specified by nr.

     DIOCGETRULESETS struct pfioc_ruleset *pr

             struct pfioc_ruleset {
                     u_int32_t        nr;
                     char             path[MAXPATHLEN];
                     char             name[PF_ANCHOR_NAME_SIZE];
             };

             Get the number nr of rulesets (i.e., anchors) directly attached
             to the anchor named by path for use in subsequent DIOCGETRULESET
             calls.  Nested anchors, since they are not directly attached to
             the given anchor, will not be included.  This ioctl returns
             EINVAL if the given anchor does not exist.

     DIOCGETRULESET struct pfioc_ruleset *pr
             Get a ruleset (i.e., an anchor) name by its number nr from the
             given anchor path, the maximum number of which can be obtained
             from a preceding DIOCGETRULESETS call.  This ioctl returns EINVAL
             if the given anchor does not exist or EBUSY if another process is
             concurrently updating a ruleset.

     DIOCADDSTATE struct pfioc_state *ps
             Add a state entry.

             struct pfioc_state {
                     struct pfsync_state     state;
             };

     DIOCGETSTATE struct pfioc_state *ps
             Extract the entry identified by the id and creatorid fields of
             the state structure from the state table.

     DIOCKILLSTATES struct pfioc_state_kill *psk
             Remove matching entries from the state table.  This ioctl returns
             the number of killed states in psk_killed.

             struct pfioc_state_kill {
                     struct pf_state_cmp     psk_pfcmp;
                     sa_family_t             psk_af;
                     int                     psk_proto;
                     struct pf_rule_addr     psk_src;
                     struct pf_rule_addr     psk_dst;
                     char                    psk_ifname[IFNAMSIZ];
                     char                    psk_label[PF_RULE_LABEL_SIZE];
                     u_int                   psk_killed;
                     u_int16_t               psk_rdomain;
             };

     DIOCCLRSTATES struct pfioc_state_kill *psk
             Clear all states.  It works like DIOCKILLSTATES, but ignores all
             fields of the pfioc_state_kill structure, except psk_ifname.

     DIOCSETSTATUSIF struct pfioc_if *pi
             Specify the interface for which statistics are accumulated.

             struct pfioc_if {
                     char             ifname[IFNAMSIZ];
             };

     DIOCGETSTATUS struct pf_status *s
             Get the internal packet filter statistics.

             struct pf_status {
                     u_int64_t       counters[PFRES_MAX];
                     u_int64_t       lcounters[LCNT_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];
                     u_int8_t        pf_chksum[MD5_DIGEST_LENGTH];
             };

     DIOCCLRSTATUS
             Clear the internal packet filter statistics.

     DIOCNATLOOK struct pfioc_natlook *pnl
             Look up a state table entry by source and destination addresses
             and ports.

             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 *level
             Set the debug level.

             enum    { PF_DEBUG_NONE, PF_DEBUG_URGENT, PF_DEBUG_MISC,
                       PF_DEBUG_NOISY };

     DIOCGETSTATES struct pfioc_states *ps
             Get state table entries.

             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
             };

             If ps_len is non-zero on entry, as many states as possible that
             can fit into this size will be copied into the supplied buffer
             ps_states.  On exit, ps_len is always set to the total size re-
             quired to hold all state table entries (i.e., it is set to
             sizeof(struct pf_state) * nr).

     DIOCCHANGERULE struct pfioc_rule *pcr
             Add or remove the rule in the ruleset specified by rule.action.

             The type of operation to be performed is indicated by action,
             which can be any of the following:

             enum    { PF_CHANGE_NONE, PF_CHANGE_ADD_HEAD, PF_CHANGE_ADD_TAIL,
                       PF_CHANGE_ADD_BEFORE, PF_CHANGE_ADD_AFTER,
                       PF_CHANGE_REMOVE, PF_CHANGE_GET_TICKET };

             ticket must be set to the value obtained with
             PF_CHANGE_GET_TICKET for all actions except PF_CHANGE_GET_TICKET.
             anchor indicates to which anchor the operation applies.  nr indi-
             cates the rule number against which PF_CHANGE_ADD_BEFORE,
             PF_CHANGE_ADD_AFTER, or PF_CHANGE_REMOVE actions are applied.

     DIOCSETTIMEOUT struct pfioc_tm *pt

             struct pfioc_tm {
                     int              timeout;
                     int              seconds;
             };

             Set the state timeout of timeout to seconds.  The old value will
             be placed into seconds.  For possible values of timeout, consult
             the PFTM_* values in <net/pfvar.h>.

     DIOCGETTIMEOUT struct pfioc_tm *pt
             Get the state timeout of timeout.  The value will be placed into
             the seconds field.

     DIOCCLRRULECTRS
             Clear per-rule statistics.

     DIOCSETLIMIT struct pfioc_limit *pl
             Set the hard limits on the memory pools used by the packet fil-
             ter.

             struct pfioc_limit {
                     int             index;
                     unsigned        limit;
             };

             enum    { PF_LIMIT_STATES, PF_LIMIT_SRC_NODES, PF_LIMIT_FRAGS,
                       PF_LIMIT_TABLES, PF_LIMIT_TABLE_ENTRIES, PF_LIMIT_MAX };

     DIOCGETLIMIT struct pfioc_limit *pl
             Get the hard limit for the memory pool indicated by index.

     DIOCRCLRTABLES struct pfioc_table *io
             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;
                     u_int32_t                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 *io
             Create one or more tables.  On entry, pfrio_buffer must point to
             an array of struct pfr_table containing at least pfrio_size ele-
             ments.  pfrio_esize must be the size of struct pfr_table.  On ex-
             it, pfrio_nadd contains the number of tables effectively created.

             struct pfr_table {
                     char            pfrt_anchor[MAXPATHLEN];
                     char            pfrt_name[PF_TABLE_NAME_SIZE];
                     u_int32_t       pfrt_flags;
                     u_int8_t        pfrt_fback;
             };

     DIOCRDELTABLES struct pfioc_table *io
             Delete one or more tables.  On entry, pfrio_buffer must point to
             an array of struct pfr_table containing at least pfrio_size ele-
             ments.  pfrio_esize must be the size of struct pfr_table.  On ex-
             it, pfrio_ndel contains the number of tables effectively deleted.

     DIOCRGETTABLES struct pfioc_table *io
             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
             anything but just returns the required buffer size, without er-
             ror.

     DIOCRGETTSTATS struct pfioc_table *io
             This call is like DIOCRGETTABLES but is used to get an array of
             pfr_tstats structures.

             struct pfr_tstats {
                     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 *io
             Clear the statistics of one or more tables.  On entry,
             pfrio_buffer must point to an array of struct pfr_table contain-
             ing at least pfrio_size elements.  pfrio_esize must be the size
             of struct pfr_table.  On exit, pfrio_nzero contains the number of
             tables effectively cleared.

     DIOCRCLRADDRS struct pfioc_table *io
             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 *io
             Add one or more addresses to a table.  On entry, pfrio_table con-
             tains the table ID and pfrio_buffer must point to an array of
             struct pfr_addr containing at least pfrio_size elements to add to
             the table.  pfrio_esize must be the size of struct pfr_addr.  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 *io
             Delete one or more addresses from a table.  On entry, pfrio_table
             contains the table ID and pfrio_buffer must point to an array of
             struct pfr_addr containing at least pfrio_size elements to delete
             from the table.  pfrio_esize must be the size of struct pfr_addr.
             On exit, pfrio_ndel contains the number of addresses effectively
             deleted.

     DIOCRSETADDRS struct pfioc_table *io
             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 must
             point to an array of struct pfr_addr containing at least
             pfrio_size elements which become the new contents of the table.
             pfrio_esize must be the size of struct pfr_addr.  Additionally,
             if pfrio_size2 is non-zero, pfrio_buffer[pfrio_size..pfrio_size2]
             must be a writeable buffer, into which the kernel can copy the
             addresses that have been deleted during the replace operation.
             On exit, pfrio_ndel, pfrio_nadd, and pfrio_nchange contain the
             number of addresses deleted, added, and changed by the kernel.
             If pfrio_size2 was set on entry, pfrio_size2 will point to the
             size of the buffer used, exactly like DIOCRGETADDRS.

     DIOCRGETADDRS struct pfioc_table *io
             Get all the addresses of a table.  On entry, pfrio_table contains
             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
             returns the required buffer size, without returning an error.

     DIOCRGETASTATS struct pfioc_table *io
             This call is like DIOCRGETADDRS but is used to get an array of
             pfr_astats structures.

             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 *io
             Clear the statistics of one or more addresses.  On entry,
             pfrio_table contains the table ID and pfrio_buffer must point to
             an array of struct pfr_addr containing at least pfrio_size ele-
             ments to be cleared from the table.  pfrio_esize must be the size
             of struct pfr_addr.  On exit, pfrio_nzero contains the number of
             addresses effectively cleared.

     DIOCRTSTADDRS struct pfioc_table *io
             Test if the given addresses match a table.  On entry, pfrio_table
             contains the table ID and pfrio_buffer must point to an array of
             struct pfr_addr containing at least pfrio_size elements, each of
             which will be tested for a match in the table.  pfrio_esize must
             be the size of struct pfr_addr.  On exit, the kernel updates the
             pfr_addr array by setting the pfra_fback member appropriately.

     DIOCRSETTFLAGS struct pfioc_table *io
             Change the PFR_TFLAG_CONST or PFR_TFLAG_PERSIST flags of a table.
             On entry, pfrio_buffer must point to an array of struct pfr_table
             containing at least pfrio_size elements.  pfrio_esize must be the
             size of struct pfr_table.  pfrio_setflag must contain the flags
             to add, while pfrio_clrflag must contain 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 PFR_TFLAG_PERSIST flag of an unreferenced table.

     DIOCRINADEFINE struct pfioc_table *io
             Defines a table in the inactive set.  On entry, pfrio_table con-
             tains the table ID and pfrio_buffer[pfrio_size] contains an array
             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 *io

             struct pfioc_trans {
                     int              size;  /* number of elements */
                     int              esize; /* size of each element in bytes */
                     struct pfioc_trans_e {
                             int             rs_num;
                             char            anchor[MAXPATHLEN];
                             u_int32_t       ticket;
                     }               *array;
             };

             Clear all the inactive rulesets specified in the 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.

             Ruleset types, identified by rs_num, include the following:

                PF_RULESET_FILTER  Filter rules.
                PF_RULESET_ALTQ    ALTQ disciplines.
                PF_RULESET_TABLE   Address tables.

     DIOCXCOMMIT struct pfioc_trans *io
             Atomically switch a vector of inactive rulesets to the active
             rulesets.  This call is implemented as a standard two-phase com-
             mit, which will either fail for all rulesets or completely suc-
             ceed.  All tickets need to be valid.  This ioctl returns EBUSY if
             another process is concurrently updating some of the same rule-
             sets.

     DIOCXROLLBACK struct pfioc_trans *io
             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.

     DIOCSETHOSTID u_int32_t *hostid
             Set the host ID, which is used by pfsync(4) to identify which
             host created state table entries.

     DIOCOSFPFLUSH
             Flush the passive OS fingerprint table.

     DIOCOSFPADD struct pf_osfp_ioctl *io

             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;
                     pf_tcpopts_t            fp_tcpopts;
                     u_int16_t               fp_wsize;
                     u_int16_t               fp_psize;
                     u_int16_t               fp_mss;
                     u_int16_t               fp_flags;
                     u_int8_t                fp_optcnt;
                     u_int8_t                fp_wscale;
                     u_int8_t                fp_ttl;
                     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, fp_optcnt, and fp_wscale are set to the TCP
             MSS, the TCP window size, the IP length, the IP TTL, the number
             of TCP options, and the TCP window scaling constant of the TCP
             SYN packet, respectively.

             The fp_flags member is filled according to the <net/pfvar.h> in-
             clude file PF_OSFP_* defines.  The fp_tcpopts member contains
             packed TCP options.  Each option uses PF_OSFP_TCPOPT_BITS bits in
             the packed value.  Options include any of PF_OSFP_TCPOPT_NOP,
             PF_OSFP_TCPOPT_SACK, PF_OSFP_TCPOPT_WSCALE, PF_OSFP_TCPOPT_MSS,
             or PF_OSFP_TCPOPT_TS.

             The fp_getnum member is not used with this ioctl.

             The structure's slack space must be zeroed for correct operation;
             memset(3) the whole structure to zero before filling and sending
             to the kernel.

     DIOCOSFPGET struct pf_osfp_ioctl *io
             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 *psn

             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 sticky addresses and source
             tracking.  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 struc-
             tures 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 ac-
             tual source node data.  After that call, psn_len will be set to
             the length of the buffer actually used.

     DIOCCLRSRCNODES
             Clear the tree of source tracking nodes.

     DIOCIGETIFACES struct pfioc_iface *io
             Get 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;
             };

             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,
             pfiio_size contains the number of pfi_kif entries that can fit
             into the buffer.  The kernel will replace this value by the real
             number of entries it wants to return.  pfiio_esize should be set
             to sizeof(struct pfi_kif).

             The data is returned in the pfi_kif structure described below:

             struct pfi_kif {
                     RB_ENTRY(pfi_kif)                pfik_tree;
                     char                             pfik_name[IFNAMSIZ];
                     u_int64_t                        pfik_packets[2][2][2];
                     u_int64_t                        pfik_bytes[2][2][2];
                     u_int32_t                        pfik_tzero;
                     int                              pfik_flags;
                     struct pf_state_tree_lan_ext     pfik_lan_ext;
                     struct pf_state_tree_ext_gwy     pfik_ext_gwy;
                     TAILQ_ENTRY(pfi_kif)             pfik_w_states;
                     void                            *pfik_ah_cookie;
                     struct ifnet                    *pfik_ifp;
                     struct ifg_group                *pfik_group;
                     int                              pfik_states;
                     int                              pfik_rules;
                     TAILQ_HEAD(, pfi_dynaddr)        pfik_dynaddrs;
             };

     DIOCSETIFFLAG struct pfioc_iface *io
             Set the user setable flags (described above) of the pf internal
             interface description.  The filtering process is the same as for
             DIOCIGETIFACES.

             #define PFI_IFLAG_SKIP  0x0100  /* skip filtering on interface */

     DIOCCLRIFFLAG struct pfioc_iface *io
             Works as DIOCSETIFFLAG above but clears the flags.

     DIOCKILLSRCNODES struct pfioc_iface *io
             Explicitly remove source tracking nodes.

FILES
     /dev/pf  packet filtering device.

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);
     }

     int
     main(int argc, char *argv[])
     {
             struct pfioc_natlook nl;
             int dev;

             if (argc != 5) {
                     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), bridge(4), pflog(4), pflow(4), pfsync(4), pf.conf(5), pfctl(8),
     altq(9)

HISTORY
     The pf packet filtering mechanism first appeared in OpenBSD 3.0.

OpenBSD 4.7                    January 12, 2010                             11
