.\" $OpenBSD: pfctl.8,v 1.34 2001/10/11 00:53:21 dhartmei Exp $ .\" .\" Copyright (c) 2001 Kjell Wooding. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. The name of the author may not be used to endorse or promote products .\" derived from this software without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd June 24, 2001 .Dt PFCTL 8 .Os .Sh NAME .Nm pfctl .Nd control the packet filter and NAT subsystems .Sh SYNOPSIS .Nm pfctl .Op Fl dehnqv .Op Fl F Ar modifier .Op Fl l Ar interface .Op Fl N Ar file .Op Fl O Ar level .Op Fl R Ar file .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 system using the ioctl interface described in .Xr pf 4 . .Pp Packet filtering lets you restrict packets entering or leaving your host; packets can be specified in a variety of ways including by protocol, by port number, and by address. Network Address Translation lets you map a series of internal host IP numbers to a single external address. The NAT code also has provisions for redirecting a range of connections to a different host and/or port number. Taken together this provides a powerful basic firewall mechanism. .Pp The .Nm command is normally invoked automatically at system initialization time to start and load the packet filter, but can also be used when the filter or translation rules change. .Pp .Nm requires the .Xr pf 4 pseudo-device driver. Forwarding packets, by using NAT, also requires specifying .Li net.inet.ip.forwarding=1 in the file .Pa /etc/sysctl.conf . .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 and counters). .It Fl F Ar all Flush all of the above. .El .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 n Do not actually load rules. .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 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 packet 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 redundant. 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 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 = 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 increase the TTL. It is permissible to set the TTL for a particular state to zero if you do not want packets matching a particular state to prolong the life of the state. 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. If you see lots of blocked packets coming back from web servers (notably Solaris), increase this value and possibly tcp.closing. .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 .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 .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 .Sh AUTHORS Daniel Hartmeier wrote the program and the underlying mechanism. .Sh HISTORY The .Nm program and the .Xr pf 4 filter mechanism first appeared in .Ox 3.0 . .Sh BUGS Probably.