path: root/sbin/pfctl/pfctl.8

.\" $OpenBSD: pfctl.8,v 1.47 2002/06/03 16:18:53 kjell Exp $
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.Dd June 24, 2001
.Dt PFCTL 8
.Os
.Sh NAME
.Nm pfctl
.Nd control the packet filter (PF) and network address translation (NAT) device
.Sh SYNOPSIS
.Nm pfctl
.Op Fl dehnqrvz
.Op Fl F Ar modifier
.Op Fl N Ar file
.Op Fl O Ar level
.Op Fl R Ar file
.Op Fl k Ar host
.Op Fl l Ar interface
.Op Fl m Ar modifier
.Op Fl s Ar modifier
.Op Fl t Ar modifier
.Op Fl x Ar level
.Sh DESCRIPTION
The
.Nm
utility communicates with the packet filter device using the
ioctl interface described in
.Xr pf 4 .
It allows rule set and parameter configuration and retrieval of status
information from the packet filter.
.Pp
Packet filtering restricts the types of packets that pass through
network interfaces entering or leaving the host based on filter
rules as described in
.Xr pf.conf 5 .
The packet filter can also replace addresses and ports of packets.
Replacing source addresses and ports of outgoing packets is called
NAT (Network Address Translation) and is used to connect an internal
network (usually reserved address space) to an external one (the
Internet) by making all connections to external hosts appear to
come from the gateway.
Replacing destination addresses and ports of incoming packets
is used to redirect connections to different hosts and/or ports.
A combination of both translations, bidirectional NAT, is also
supported.
Translation rules are described in
.Xr nat.conf 5 .
.Pp
When the variable pf=YES is set in
.Xr rc.conf 8 ,
the rule files specified with the variables pf_rules and nat_rules
are loaded automatically by the
.Xr rc 8
scripts and the packet filter is enabled.
.Pp
The packet filter does not itself forward packets between interfaces.
Forwarding can be enabled using the
.Xr sysctl 8
variable
.Li net.inet.ip.forwarding=1 ,
permanently in
.Xr sysctl.conf 5 .
.Pp
The
.Nm
utility provides several commands.
The options are as follows:
.Bl -tag -width Ds
.It Fl d
Disable the packet filter.
.It Fl e
Enable the packet filter.
.It Fl F Ar modifier
Flush one of the following.
Modifier name may be abbreviated:
.Bl -tag -width "F rules " -compact
.It Fl F Ar nat
Flush the NAT rules.
.It Fl F Ar rules
Flush the filter rules.
.It Fl F Ar state
Flush the state table (NAT and filter).
.It Fl F Ar info
Flush the filter information (statistics that are not bound to rules).
.It Fl F Ar all
Flush all of the above.
.El
.It Fl k Ar host
Kill all of the state entries from the specified host.
A second
.Fl k Ar host
option may be specified, which will kill all the state entries
from the first host to the second host.
.Bd -literal
Example:
      Kill all of the state entries from host
    # pfctl -k host

      Kill all of the state entries from host1 to host2
    # pfctl -k host1 -k host2
.Ed
.It Fl h
Help.
.It Fl l Ar interface
Enable collection of packet and byte count statistics for interface named
.Ar interface .
These statistics can be viewed with the
.Fl s Ar info
option.
.It Fl m Ar modifier
Gets or sets hard limits on the memory pools used by the packet filter.
See
.Xr pool 9
for an explanation of memory pools.
The modifier has the form name[=limit], where name specifies one of the
following pools and limit is either a positive integer (maximum number
of pool entries) or the string "inf" (removes the limit):
.Bl -tag -width "m states[=limit] " -compact
.It Fl m Ar states[=limit]
Maximum number of entries in the memory pool used by state table
entries (generated by 'keep state' rules).
.It Fl m Ar frags[=limit]
Maximum number of entries in the memory pool used for fragment
caching (generated by 'scrub' rules).
.It Fl m Ar all
Display all maxima, cannot be set.
.El
.It Fl n
Do not actually load rules, just parse them.
.It Fl N Ar file
Load a NAT rules file.
.It Fl O Ar modifier
Optimize the engine to one of the following network topographies or
environments:
.Bl -tag -width "O high-latency " -compact
.It Fl O Ar default
A normal network environment.
Suitable for almost all networks.
.It Fl O Ar normal
Alias for
.Em default
.It Fl O Ar high-latency
A high-latency environment (such as a satellite connection)
.It Fl O Ar satellite
Alias for
.Em high-latency
.It Fl O Ar aggressive
Aggressively expire connections when they are likely no longer valid.
This can greatly reduce the memory usage of the firewall at the cost of
dropping idle connections early.
.It Fl O Ar conservative
Extremely conservative settings.
Pains will be taken to avoid dropping legitimate connections at the
expense of greater memory utilization (possibly much greater on a busy
network) and slightly increased processor utilization.
.El
Currently the optimizations only encompass the state table timeouts but much
more is planned in future revisions of the finite state machines (FSMs).
.It Fl q
Only print errors and warnings.
.It Fl r
Perform reverse DNS lookups on states when displaying them.
.It Fl R Ar file
Load a filter rules file into the filter.
.It Fl s Ar modifier
Show filter parameters.
Modifier names may be abbreviated:
.Bl -tag -width "s rules " -compact
.It Fl s Ar nat
Show the currently loaded NAT rules.
.It Fl s Ar rules
Show the currently loaded filter rules.
When used together with -v, the per-rule statistics (number of evaluations,
packets and bytes) are also shown.
Note that the 'skip step' optimization done automatically by the kernel
will skip evaluation of rules where possible.
Packets passed statefully are counted in the rule that created the state
(even though the rule isn't evaluated more than once for the entire
connection).
.It Fl s Ar state
Show the contents of the state table.
.It Fl s Ar info
Show filter information (statistics and counters).
.It Fl s Ar labels
Show per-rule statistics (in terse format) of filter rules with labels,
useful for accounting.
.It Fl s Ar all
Show all of the above.
.El
.It Fl t Ar modifier
Get a timeout or interval value.
Any of the modifiers may be set, with the exception of
.Em all ,
by appending =<seconds> to the modifier without any whitespace seperating
the modifier, the equals and the number of seconds.
.Bl -tag -width "t interval " -compact
.It Fl t Ar all
Display all timeouts and intervals.
.It Fl t Ar interval
Interval between purging expired states and fragments.
.It Fl t Ar frag
Seconds before an unassembled fragment is expired.
.El
.Pp
When a packet matches a stateful connection, the seconds to live of the
connection will be updated to that of the proto.modifier which corresponds
to the connection state.
Each packet which matches this state will reset the TTL.
Tuning these values may improve the performance of the
firewall at the risk of dropping valid idled connections.
.Bl -tag -width "t tcp.established " -compact
.It Fl t Ar tcp.first
The state after the first packet.
.It Fl t Ar tcp.opening
The state before the destination host ever sends a packet.
.It Fl t Ar tcp.established
The fully established state.
.It Fl t Ar tcp.closing
The state after the first FIN has been sent.
.It Fl t Ar tcp.finwait
The state after both FINs have been exchanged and the connection is closed.
Some hosts (notably web servers on Solaris) send TCP packets even after closing
the connection.
Increasing tcp.finwait (and possibly tcp.closing) can prevent blocking of
such packets.
.It Fl t Ar tcp.closed
The state after one endpoint sends a RST.
.El
.Pp
ICMP and UDP are handled in a similar fashion to TCP but with a much more
limited set of states:
.Bl -tag -width "t udp.multiple " -compact
.It Fl t Ar udp.first
The state after the first packet.
.It Fl t Ar udp.single
The state if the source host sends more than one packet but the destination
host has never sent one back.
.It Fl t Ar udp.multiple
The state if both hosts have sent packets.
.It Fl t Ar icmp.first
The state after the first packet.
.It Fl t Ar icmp.error
The state after an icmp error came back in response to an icmp packet.
.El
.Pp
Other protocols are handled similarly to UDP:
.Bl -tag -width "t other.multiple " -compact
.It Fl t Ar other.first
.It Fl t Ar other.single
.It Fl t Ar other.multiple
.El
.Bd -literal
Example:
      Timeout established connections after an hour of inactivity
    # pfctl -t tcp.established=3600

      Display the current established idle timeout
    # pfctl -t tcp.established
.Ed
.It Fl v
Produce more verbose output.
.It Fl x Ar level
Set the debug level to one of the following.
Level names may be abbreviated:
.Bl -tag -width "x urgent " -compact
.It Fl x Ar none
Don't generate debug messages.
.It Fl x Ar urgent
Generate debug messages only for serious errors.
.It Fl x Ar misc
Generate debug messages for various errors.
.El
.It Fl z
Clear per-rule statistics.
.El
.Sh FILES
.Bl -tag -width "/etc/nat.conf" -compact
.It Pa /etc/pf.conf
Packet filter rules file.
.It Pa /etc/nat.conf
Rules for Network Address Translation.
.El
.Sh SEE ALSO
.Xr pf 4 ,
.Xr nat.conf 5 ,
.Xr pf.conf 5 ,
.Xr ftp-proxy 8 ,
.Xr rc 8 ,
.Xr rc.conf 8 ,
.Xr sysctl 8 ,
.Xr sysctl.conf 8
.Sh HISTORY
The
.Nm
program and the
.Xr pf 4
filter mechanism first appeared in
.Ox 3.0 .