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.
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 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.
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 speci-
fied 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
pfioc_state_kill 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 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.
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 oper-
ation 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 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_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 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.
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), pfsync(4), pfctl(8), altq(9)
HISTORY
The pf packet filtering mechanism first appeared in OpenBSD 3.0.
OpenBSD 4.1 June 24, 2001 12