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

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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, /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 rule sets,
add and remove individual rules or retrieve state table entries and
statistics.
The most commonly used functions are covered by
.Xr pfctl 8 .
.Pp
Manipulations like loading a rule set that involve more than a single
ioctl call require a so-called ticket, which prevents the occurance 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 DIOCBEGINRULES  Fa "u_int32_t"
Clears the inactive filter rule set, returns ticket for subsequent
DIOCADDRULE and DIOCCOMMITRULES calls.
.It Dv DIOCADDRULE     Fa "struct pfioc_rule"
.Bd -literal
struct pfioc_rule {
	u_int32_t	 ticket;
	u_int32_t	 nr;
	struct pf_rule	 rule;
};
.Ed
.Pp
Adds filter
.Va rule
at the end of the inactive filter rule set.
Requires
.Va ticket
obtained through preceding DIOCBEGINRULES call.
.Va nr
is ignored.
.It Dv DIOCCOMMITRULES Fa "u_int32_t"
Switch inactive to active filter rule set.
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 filter rule set.
.It Dv DIOCGETRULE     Fa "struct pfioc_rule"
Returns filter
.Va rule
number
.Va nr
using
.Va ticket
obtained through a preceding DIOCGETRULES call.
.It Dv DIOCBEGINNATS   Fa "u_int32_t"
.It Dv DIOCADDNAT      Fa "struct pfioc_nat"
.Bd -literal
struct pfioc_nat {
	u_int32_t	 ticket;
	u_int32_t	 nr;
	struct pf_nat	 nat;
};
.Ed
.It Dv DIOCCOMMITNATS  Fa "u_int32_t"
.It Dv DIOCGETNATS     Fa "struct pfioc_nat"
.It Dv DIOCGETNAT      Fa "struct pfioc_nat"
.It Dv DIOCBEGINBINATS Fa "u_int32_t"
.It Dv DIOCADDBINAT    Fa "struct pfioc_binat"
.Bd -literal
struct pfioc_binat {
	u_int32_t	 ticket;
	u_int32_t	 nr;
	struct pf_binat	 binat;
};
.Ed
.It Dv DIOCCOMMITBINATS Fa "u_int32_t"
.It Dv DIOCGETBINATS   Fa "struct pfioc_binat"
.It Dv DIOCGETBINAT    Fa "struct pfioc_binat"
.It Dv DIOCBEGINRDRS   Fa "u_int32_t"
.It Dv DIOCADDRDR      Fa "struct pfioc_rdr"
.Bd -literal
struct pfioc_rdr {
	u_int32_t	 ticket;
	u_int32_t	 nr;
	struct pf_rdr	 rdr;
};
.Ed
.It Dv DIOCCOMMITRDRS  Fa "u_int32_t"
.It Dv DIOCGETRDRS     Fa "struct pfioc_rdr"
.It Dv DIOCGETRDR      Fa "struct pfioc_rdr"
.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_changerule"
Adds or removes a filter rule in the active filter rule set.
.Bd -literal
struct pfioc_changerule {
	u_int32_t	 action;
	struct pf_rule	 oldrule;
	struct pf_rule	 newrule;
};

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 };
.Ed
.It Dv DIOCCHANGENAT   Fa "struct pfioc_changenat"
Adds or removes a nat rule in the active nat rule set.
.Bd -literal
struct pfioc_changenat {
	u_int32_t	 action;
	struct pf_nat	 oldnat;
	struct pf_nat	 newnat;
};
.Ed
.It Dv DIOCCHANGEBINAT   Fa "struct pfioc_changebinat"
Adds or removes a binat rule in the active binat rule set.
.Bd -literal
struct pfioc_changebinat {
	u_int32_t	action;
	struct pf_binat	oldbinat;
	struct pf_binat	newbinat;
};
.Ed
.It Dv DIOCCHANGERDR   Fa "struct pfioc_changerdr"
Adds or removes a rdr rule in the active rdr rule set.
.Bd -literal
struct pfioc_changerdr {
	u_int32_t	 action;
	struct pf_rdr	 oldrdr;
	struct pf_rdr	 newrdr;
};
.Ed
.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"
.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 <stdio.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(0, "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(0, "DIOCNATLOOK");

	printf("internal host ");
	print_address(nl.rsaddr.v4.s_addr);
	printf(":%u\\n", ntohs(nl.rsport));
	return 0;
}
.Ed
.Sh SEE ALSO
.Xr bridge 4 ,
.Xr pflog 4 ,
.Xr pfctl 8
.Sh HISTORY
The
.Nm
packet filtering mechanism first appeared in
.Ox 3.0 .