path: root/share/man/man4/pf.4

.\"	$OpenBSD: pf.4,v 1.36 2003/08/22 21:50:34 david Exp $
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.Dd June 24, 2001
.Dt PF 4
.Os
.Sh NAME
.Nm pf
.Nd packet filter
.Sh SYNOPSIS
.Cd "pseudo-device pf 1"
.Sh DESCRIPTION
Packet filtering takes place in the kernel.
A pseudo-device,
.Pa /dev/pf ,
allows userland processes to control the
behavior of the packet filter through an
.Xr 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
.Xr pfctl 8 .
.Pp
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.
.Pp
Fields of ioctl parameter structures that refer to packet data (like
addresses and ports) are generally expected in network byte-order.
.Sh FILES
.Bl -tag -width /dev/pf -compact
.It Pa /dev/pf
packet filtering device.
.El
.Sh IOCTL INTERFACE
pf supports the following
.Xr ioctl 2
commands:
.Bl -tag -width xxxxxx
.It Dv DIOCSTART
Starts the packet filter.
.It Dv DIOCSTOP
Stops the packet filter.
.It Dv DIOCSTARTALTQ
Starts the ALTQ bandwidth control system.
.It Dv DIOCSTOPALTQ
Stops the ALTQ bandwidth control system.
.It Dv DIOCBEGINADDRS  Fa "u_int32_t"
Clears the buffer address pool
and returns a ticket for subsequent DIOCADDADDR, DIOCADDRULE and
DIOCCHANGERULE calls.
.It Dv DIOCADDADDR     Fa "struct pfioc_pooladdr"
.Bd -literal
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;
};
.Ed
.Pp
Adds pool address
.Va addr
to the buffer address pool to be used in the following
DIOCADDRULE or DIOCCHANGERULE call.
All other members of the structure are ignored.
.It Dv DIOCBEGINRULES  Fa "u_int32_t"
Clears the inactive ruleset for the type of rule indicated by
.Va rule.action
and returns a ticket for subsequent
DIOCADDRULE and DIOCCOMMITRULES calls.
.It Dv DIOCADDRULE     Fa "struct pfioc_rule"
.Bd -literal
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;
};
.Ed
.Pp
Adds
.Va rule
at the end of the inactive ruleset.
Requires
.Va ticket
obtained through preceding DIOCBEGINRULES call, and
.Va pool_ticket
obtained through DIOCBEGINADDRS call.
DIOCADDADDR must also be called if any pool addresses are required.
The optional
.Va anchor
and
.Va ruleset
names indicate the anchor and ruleset in which to append the rule.
.Va nr
and
.Va action
are ignored.
.It Dv DIOCCOMMITRULES Fa "u_int32_t"
Switch inactive to active filter ruleset.
Requires
.Va ticket .
.It Dv DIOCBEGINALTQS  Fa "u_int32_t"
Clears the inactive list of queues and returns a ticket for subsequent
DIOCADDALTQ and DIOCCOMMITALTQS calls.
.It Dv DIOCADDALTQ     Fa "struct pfioc_altq"
Adds
.Bd -literal
struct pfioc_altq {
	u_int32_t	ticket;
	u_int32_t	nr;
	struct pf_altq   altq;
};
.Ed
.It Dv DIOCCOMMITALTQS Fa "u_int32_t"
Switch inactive to active list of queues.
Requires
.Va ticket .
.It Dv DIOCGETRULES    Fa "struct pfioc_rule"
Returns
.Va ticket
for subsequent DIOCGETRULE calls and
.Va nr
of rules in the active ruleset.
.It Dv DIOCGETRULE     Fa "struct pfioc_rule"
Returns
.Va rule
number
.Va nr
using
.Va ticket
obtained through a preceding DIOCGETRULES call.
.It Dv DIOCGETADDRS    Fa "struct pfioc_pooladdr"
Returns
.Va ticket
for subsequent DIOCGETADDR calls and
.Va nr
of pool addresses in the rule specified with
.Va r_action ,
.Va r_num ,
.Va anchor
and
.Va ruleset .
.It Dv DIOCGETADDR     Fa "struct pfioc_pooladdr"
Returns pool address
.Va addr
number
.Va nr
from the rule specified with
.Va r_action ,
.Va r_num ,
.Va anchor
and
.Va ruleset
using
.Va ticket
obtained through a preceding DIOCGETADDRS call.
.It Dv DIOCGETALTQS    Fa "struct pfioc_altq"
Returns
.Va ticket
for subsequent DIOCGETALTQ calls and
.Va nr
of queues in the active list.
.It Dv DIOCGETALTQ     Fa "struct pfioc_altq"
Returns
.Va altq
number
.Va nr
using
.Va ticket
obtained through a preceding DIOCGETALTQS call.
.It Dv DIOCGETQSTATS   Fa "struct pfioc_qstats"
Returns statistics on a queue.
.Bd -literal
struct pfioc_qstats {
	u_int32_t	 ticket;
	u_int32_t	 nr;
	void		*buf;
	int		 nbytes;
	u_int8_t	 scheduler;
};
.Ed
.Pp
A pointer to a buffer of statistics
.Va buf
of length
.Va nbytes
for the queue specified by
.Va nr .
.It Dv DIOCCLRSTATES
Clears the state table.
.It Dv DIOCADDSTATE    Fa "struct pfioc_state"
Adds a state entry.
.It Dv DIOCGETSTATE    Fa "struct pfioc_state"
.Bd -literal
struct pfioc_state {
	u_int32_t	 nr;
	struct pf_state	 state;
};
.Ed
.Pp
Extracts the entry with the specified number from the state table.
.It Dv DIOCKILLSTATES  Fa "struct pfioc_state_kill"
Removes matching entries from the state table.
Returns the number of killed states in psk_af.
.Bd -literal
struct pfioc_state_kill {
	int			psk_af;
	int			psk_proto;
	struct pf_rule_addr	psk_src;
	struct pf_rule_addr	psk_dst;
};
.Ed
.It Dv DIOCSETSTATUSIF Fa "struct pfioc_if"
.Bd -literal
struct pfioc_if {
	char		 ifname[IFNAMSIZ];
};
.Ed
.Pp
Specifies the interface for which statistics are accumulated.
.It Dv DIOCGETSTATUS   Fa "struct pf_status"
.Bd -literal
struct pf_status {
	u_int64_t	 counters[PFRES_MAX];
	u_int64_t	 fcounters[FCNT_MAX];
	u_int64_t	 pcounters[2][2][3];
	u_int64_t	 bcounters[2][2];
	u_int32_t	 running;
	u_int32_t	 states;
	u_int32_t	 since;
	u_int32_t	 debug;
};
.Ed
.Pp
Gets the internal packet filter statistics.
.It Dv DIOCCLRSTATUS
Clears the internal packet filter statistics.
.It Dv DIOCNATLOOK     Fa "struct pfioc_natlook"
Looks up a state table entry by source and destination addresses and ports.
.Bd -literal
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;
	u_int8_t	 af;
	u_int8_t	 proto;
	u_int8_t	 direction;
};
.Ed
.It Dv DIOCSETDEBUG    Fa "u_int32_t"
Sets the debug level.
.Bd -literal
enum	{ PF_DEBUG_NONE=0, PF_DEBUG_URGENT=1, PF_DEBUG_MISC=2 };
.Ed
.It Dv DIOCGETSTATES   Fa "struct pfioc_states"
.Bd -literal
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
};
.Ed
.It Dv DIOCCHANGERULE  Fa "struct pfioc_rule"
Adds or removes the
.Va rule
in the ruleset specified by
.Va rule.action .
.Bd -literal
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 };
.Ed
.Pp
The type of operation to be performed is indicated by
.Va action .
.Pp
.Va ticket
must be set to the value obtained with PF_CHANGE_GET_TICKET
for all actions except PF_CHANGE_GET_TICKET.
.Va 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.
.Pp
.Va anchor
and
.Va ruleset
indicate which anchor and ruleset the operation applies to.
.Va nr
indicates the rule number against which PF_CHANGE_ADD_BEFORE,
PF_CHANGE_ADD_AFTER or PF_CHANGE_REMOVE actions are applied.
.It Dv DIOCCHANGEADDR  Fa "struct pfioc_pooladdr"
Adds or removes a pool address
.Va addr
from a rule specified with
.Va r_action ,
.Va r_num ,
.Va anchor
and
.Va ruleset .
.It Dv DIOCSETTIMEOUT  Fa "struct pfioc_tm"
.Bd -literal
struct pfioc_tm {
	int		 timeout;
	int		 seconds;
};
.Ed
.It Dv DIOCGETTIMEOUT  Fa "struct pfioc_tm"
.It Dv DIOCCLRRULECTRS
Clear per-rule statistics.
.It Dv DIOCSETLIMIT   Fa "struct pfioc_limit"
Sets hard limits on the memory pools used by the packet filter.
.Bd -literal
struct pfioc_limit {
	int		index;
	unsigned	limit;
};
.Ed
.It Dv DIOCGETLIMIT   Fa "struct pfioc_limit"
.It Dv DIOCRCLRTABLES Fa "struct pfioc_table"
Clear all tables.
All the IOCTLs that manipulate radix tables
use the same structure described below.
For
.Dv DIOCRCLRTABLES, pfrio_ndel contains on exit the number
of tables deleted.
.Bd -literal
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
.Ed
.It Dv DIOCRADDTABLES Fa "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.
.Bd -literal
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;
};
.Ed
.It Dv DIOCRDELTABLES Fa "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.
.It Dv DIOCRGETTABLES Fa "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 anything but just
returns the required buffer size, without error.
.It Dv DIOCRGETTSTATS Fa "struct pfioc_table"
Like
.Dv DIOCRGETTABLES ,
but returns an array of pfr_tstats structures.
.Bd -literal
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
.Ed
.It Dv DIOCRCLRTSTATS Fa "struct pfioc_table"
Clears the statistics of one or more tables.
On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures.
On exit, pfrio_nzero contains the number of tables effectively cleared.
.It Dv DIOCRCLRADDRS Fa "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.
.It Dv DIOCRADDADDRS Fa "struct pfioc_table"
Add one or more addresses to a table.
On entry, pfrio_table contains 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.
.Bd -literal
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
.Ed
.It Dv DIOCRDELADDRS Fa "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 contains the number of addresses effectively deleted.
.It Dv DIOCRSETADDRS Fa "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 members.
On entry, pfrio_table contains the table id and pfrio_buffer[pfrio_size]
contains the new list of pfr_addr structures.
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 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
.Dv DIOCRGETADDRS .
.It Dv DIOCRGETADDRS Fa "struct pfioc_table"
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 pfr_addr 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
return the required buffer size, without returning an error.
.It Dv DIOCRGETASTATS Fa "struct pfioc_table"
Like
.Dv DIOCRGETADDRS ,
but returns an array of pfr_astats structures.
.Bd -literal
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;
};
.Ed
.It Dv DIOCRCLRASTATS Fa "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.
.It Dv DIOCRTSTADDRS Fa "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 table of pfr_addr structures to test.
On exit, the kernel updates the pfr_addr table by setting the pfra_fback
member appropriately.
.It Dv DIOCRSETTFLAGS Fa "struct pfioc_table"
Change the
.Va const
or
.Va persist
flag of a table.
On entry, pfrio_buffer[pfrio_size] contains a table of pfr_table structures,
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
.Va persist
flag of an unreferenced table.
.It Dv DIOCRINABEGIN Fa "struct pfioc_table"
Starts a transaction with the inactive set of tables.
Cleans up any leftover from a previously aborted transaction, and returns
a new ticket.
On exit, pfrio_ndel contains the number of leftover table deleted, and
pfrio_ticket contains a valid ticket to use for the following two IOCTLs.
.It Dv DIOCRINACOMMIT Fa "struct pfioc_table"
Commit the inactive set of tables into the active set.
While copying the addresses, do a best effort to keep statistics for
addresses present before and after the commit.
On entry, io->pfrio_ticket takes a valid ticket.
On exit, io->pfrio_nadd and io->pfrio_nchange contain the number of tables
added and altered by the commit operation.
.It Dv DIOCRINADEFINE Fa "struct pfioc_table"
Defines a table in the inactive set.
On entry, pfrio_table contains 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.
.It Dv DIOCFPFLUSH
Flush the passive OS fingerprint table.
.It Dv DIOCFPADD Fa "struct pf_osfp_ioctl"
.Bd -literal
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;
};
.Ed
.Pp
Add a passive OS fingerprint to the table.
Set
.Va fp_os.fp_os
to the packed fingerprint,
.Va fp_os.fp_class_nm
to the name of the class (Linux, Windows, etc),
.Va fp_os.fp_version_nm
to the name of the version (NT, 95, 98), and
.Va fp_os.fp_subtype_nm
to the name of the subtype or patchlevel.
The members
.Va fp_mss
.Va fp_wsize
.Va fp_psize
.Va fp_ttl
and
.Va 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
.Va fp_flags
member is filled according to the net/pfvar.h include file PF_OSFP_* defines.
The
.Va fp_getnum
is not used with this ioctl.
.Pp
The structure's slack space must be zeroed for correct operation; memset
the whole structure to zero before filling and sending to the kernel.
.It Dv DIOCFPGET Fa "struct pf_osfp_ioctl"
.Bd -literal
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;
};
.Ed
.Pp
Get the passive OS fingerprint number
.Va fp_getnum
from the kernels fingerprint list.
The rest of the structure members will come back filled.
Get the whole list by repeatedly incrementing the
.Va fp_getnum
number until the ioctl returns EBUSY.
.El
.Sh EXAMPLES
The following example demonstrates how to use the DIOCNATLOOK command
to find the internal host/port of a NATed connection.
.Bd -literal
#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;
}
.Ed
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr bridge 4 ,
.Xr pflog 4 ,
.Xr pfsync 4 ,
.Xr pfctl 8
.Sh HISTORY
The
.Nm
packet filtering mechanism first appeared in
.Ox 3.0 .