$Mdocdate$ 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 servicing 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 hierarchies are laid out. The final component of the anchor path is the anchor under which operations will be performed.

### 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.

```DIOCBEGINADDRS````struct pfioc_pooladdr *pp`
  `

      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[MAXPATHLEN];
              struct pf_pooladdr      addr;
      };

  `

  Clear the buffer address pool and get a ticket for subsequent ```DIOCADDADDR`, ```DIOCADDRULE`, and ```DIOCCHANGERULE` calls.

```DIOCADDADDR````struct pfioc_pooladdr *pp`

  Add the pool address addr to the buffer address pool to be used in the following ```DIOCADDRULE` or ```DIOCCHANGERULE` call. All other members of the structure are ignored.

```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 and a pool_ticket obtained through a ```DIOCBEGINADDRS` call. ```DIOCADDADDR` must also be called if any pool addresses are required. The optional 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.

```DIOCGETADDRS````struct pfioc_pooladdr *pp`
  Get a ticket for subsequent ```DIOCGETADDR` calls and the number nr of pool addresses in the rule specified with r_action, r_num, and anchor.

```DIOCGETADDR````struct pfioc_pooladdr *pp`
  Get the pool address addr by its number nr from the rule specified with r_action, r_num, and anchor using the ticket obtained through a preceding ```DIOCGETADDRS` call.

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

  `

```DIOCGETSTATE````struct pfioc_state *ps`
  Extract the entry with the specified number nr 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_af. `

      struct pfioc_state_kill {
              sa_family_t             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 *psk`
  Clear all states. It works like ```DIOCKILLSTATES`, but ignores the psk_af, psk_proto, psk_src, and psk_dst fields of the structure.

```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 required 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`. pool_ticket must be set to the value obtained with the ```DIOCBEGINADDRS` call for all actions except ```PF_CHANGE_REMOVE` and ```PF_CHANGE_GET_TICKET`. anchor indicates to which anchor the operation applies. 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 *pca`
  Add or remove the pool address addr from the rule specified by r_action, r_num, and anchor.

```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 filter. `

      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 containing at least elements. must be the size of On exit, 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 containing at least elements. must be the size of On exit, 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 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 error.

```DIOCRGETTSTATS````struct pfioc_table *io`
  This call is like ```DIOCRGETTABLES` but is used to get an array of 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 containing at least elements. must be the size of 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 contains the table ID and pfrio_buffer must point to an array of containing at least elements to add to the table. must be the size of 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 containing at least elements to delete from the table. must be the size of 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 members.

  On entry, pfrio_table contains the table ID and pfrio_buffer must point to an array of containing at least elements which become the new contents of the table. must be the size of 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 writeable buffer for structures. On exit, pfrio_size contains 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 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 containing at least elements to be cleared from the table. must be the size of 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 containing at least elements, each of which will be tested for a match in the table. must be the size of On exit, the kernel updates the 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 containing at least elements. pfrio_esize must be the size of 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 contains the table ID and pfrio_buffer[pfrio_size] contains an array of 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 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_SCRUB`
    Scrub (packet normalization) rules.
  ```PF_RULESET_FILTER`
    Filter rules.
  ```PF_RULESET_NAT`
    NAT (Network Address Translation) rules.
  ```PF_RULESET_BINAT`
    Bidirectional NAT rules.
  ```PF_RULESET_RDR`
    Redirect 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 commit, which will either fail for all rulesets or completely succeed. All tickets need to be valid. This ioctl returns ```EBUSY` if another process is concurrently updating some of the same rulesets.

```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`> include 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 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 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 . 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 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 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.

### 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
    #include
    #include
    #include
    #include
    #include
    #include
    #include
    #include
    #include

    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    \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), pfctl(8), altq(9)

### HISTORY

The pf packet filtering mechanism first appeared in OpenBSD3.0.

### CAVEATS

The following functionality is missing from pf in this version of NetBSD:

- The pfsync protocol is not supported.

- The group keyword is not supported.