pfctl.8

.\" $OpenBSD: pfctl.8,v 1.99 2003/08/22 21:50:34 david Exp $
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.\" Copyright (c) 2001 Kjell Wooding.  All rights reserved.
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.Dd November 20, 2002
.Dt PFCTL 8
.Os
.Sh NAME
.Nm pfctl
.Nd "control the packet filter (PF) and network address translation (NAT) device"
.Sh SYNOPSIS
.Nm pfctl
.Bk -words
.Op Fl AdeghnNqrROvz
.Op Fl a Ar anchor Ns Op Ar :ruleset
.Op Fl D Ar macro=value
.Op Fl f Ar file
.Op Fl F Ar modifier
.Op Fl k Ar host
.Op Fl s Ar modifier
.Op Fl t Ar table
.Op Fl T Ar command Op Ar address ...
.Op Fl x Ar level
.Ek
.Sh DESCRIPTION
The
.Nm
utility communicates with the packet filter device using the
ioctl interface described in
.Xr pf 4 .
It allows ruleset 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 pf.conf 5 .
.Pp
When the variable pf is set to YES in
.Xr rc.conf 8 ,
the rule file specified with the variable pf_rules
is 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 by setting the
.Xr sysctl 8
variables
.Em net.inet.ip.forwarding
and/or
.Em net.inet6.ip6.forwarding ,
to 1.
Set them permanently in
.Xr sysctl.conf 5 .
.Pp
The
.Nm
utility provides several commands.
The options are as follows:
.Bl -tag -width Ds
.It Fl a Ar anchor Ns Op Ar :ruleset
Apply flags
.Fl f ,
.Fl F
and
.Fl s
only to the rules in the specified
.Ar anchor
and optional named ruleset
.Ar ruleset .
In addition to the main ruleset,
.Nm
can load and manipulate additional rulesets by name.
Named rulesets are attached at
.Ar anchor
points, which are also referenced by name.
Evaluation of
.Ar anchor
rules from the main ruleset is described in
.Xr pf.conf 5 .
For example, to show all filter rules inside anchor
.Li foo :
.Bd -literal -offset indent
# pfctl -a foo -s rules
.Ed
.It Fl A
Load only the queue rules present in the rule file.
Other rules and options are ignored.
.It Fl d
Disable the packet filter.
.It Fl D Ar macro=value
Define
.Ar macro
to be set to
.Ar value
on the command line.
Overrides the definition of
.Ar macro
in the ruleset.
.It Fl e
Enable the packet filter.
.It Fl f Ar file
Load the rules contained in
.Ar file .
This
.Ar file
may contain macros, tables, options, and normalization, queueing,
translation, and filtering rules.
With the exception of macros and tables, the statements must appear in that
order.
.It Fl F Ar modifier
Flush the filter parameters specified by
.Ar modifier
(may be abbreviated):
.Bl -tag -width xxxxxxxxxxxx -compact
.It Fl F Ar nat
Flush the NAT rules.
.It Fl F Ar queue
Flush the queue 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 Tables
Flush the tables.
.It Fl F Ar osfp
Flush the passive operating system fingerprints.
.It Fl F Ar all
Flush all of the above.
.El
.It Fl g
Include output helpful for debugging.
.It Fl k Ar host
Kill all of the state entries originating from the specified
.Ar host .
A second
.Fl k Ar host
option may be specified, which will kill all the state entries
from the first
.Ar host
to the second
.Ar host .
For example, to kill all of the state entries originating from
.Li host :
.Bd -literal -offset indent
# pfctl -k host
.Ed
.Pp
To kill all of the state entries from
.Li host1
to
.Li host2 :
.Bd -literal -offset indent
# pfctl -k host1 -k host2
.Ed
.It Fl h
Help.
.It Fl n
Do not actually load rules, just parse them.
.It Fl N
Load only the NAT rules present in the rule file.
Other rules and options are ignored.
.It Fl q
Only print errors and warnings.
.It Fl r
Perform reverse DNS lookups on states when displaying them.
.It Fl R
Load only the filter rules present in the rule file.
Other rules and options are ignored.
.It Fl O
Load only the options present in the rule file.
Other rules and options are ignored.
.It Fl s Ar modifier
Show the filter parameters specified by
.Ar modifier
(may be abbreviated):
.Bl -tag -width xxxxxxxxxxxx -compact
.It Fl s Ar nat
Show the currently loaded NAT rules.
.It Fl s Ar queue
Show the currently loaded queue rules.
When used together with
.Fl v ,
per-queue statistics are also shown.
When used together with
.Fl v v ,
.Nm
will loop and show updated queue statistics every five seconds, including
measured bandwidth and packets per second.
.It Fl s Ar rules
Show the currently loaded filter rules.
When used together with
.Fl 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 Anchors
Show the currently loaded anchors.
If
.Fl a Ar anchor
is specified as well, the named rulesets currently loaded in the specified
anchor are shown instead.
.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 (label, evaluations, packets, bytes) of
filter rules with labels, useful for accounting.
.It Fl s Ar timeouts
Show the current global timeouts.
.It Fl s Ar memory
Show the current pool memory hard limits.
.It Fl s Ar Tables
Show the list of tables.
.It Fl s Ar osfp
Show the list of operating system fingerprints.
Can be used in combination with
.Fl o Ar file
to list the fingerprints in a
.Xr pf.os 5
file.
.It Fl s Ar all
Show all of the above.
.El
.It Fl t Ar table
Specify the name of the table.
.It Fl T Ar command Op Ar address ...
Specify the
.Ar command
(may be abbreviated) to apply to the table.
Commands include:
.Bl -tag -width xxxxxxxxxxxx -compact
.It Fl T Ar kill
Kill a table.
.It Fl T Ar flush
Flush all addresses of a table.
.It Fl T Ar add
Add one or more addresses in a table.
Automatically create a nonexisting table.
.It Fl T Ar delete
Delete one or more addresses from a table.
.It Fl T Ar replace
Replace the addresses of the table.
Automatically create a nonexisting table.
.It Fl T Ar show
Show the content (addresses) of a table.
.It Fl T Ar test
Test if the given addresses match a table.
.It Fl T Ar zero
Clear all the statistics of a table.
.It Fl T Ar load
Load only the table definitions from
.Xr pf.conf 5 .
This is used in conjunction with the
.Fl f
flag, as in:
.Bd -literal -offset indent
# pfctl -Tl -f pf.conf
.Ed
.El
.Pp
For the
.Ar add ,
.Ar delete ,
.Ar replace
and
.Ar test
commands, the list of addresses can be specified either directly on the command
line and/or in an unformatted text file, using the
.Fl f
flag.
Comments starting with a "#" are allowed in the text file.
With these commands, the
.Fl v
flag can also be used once or twice, in which case
.Nm pfctl
will print the
detailed result of the operation for each individual address, prefixed by
one of the following letters:
.Pp
.Bl -tag -width XXX -compact
.It A
The address/network has been added.
.It C
The address/network has been changed (negated).
.It D
The address/network has been deleted.
.It M
The address matches (test operation only).
.It X
The address/network is duplicated and therefore ignored.
.It Y
The address/network cannot be added/deleted due to conflicting "!" attribute.
.It Z
The address/network has been cleared (statistics).
.El
.Pp
Each table maintains a set of counters that can be retrieved using the
.Fl v
flag of
.Nm pfctl .
For example, the following commands define a wide open firewall which will keep
track of packets going to or coming from the
.Ox
ftp server.
The following commands configure the firewall and send 10 pings to the ftp
server:
.Bd -literal -offset indent
# printf \&"table <test> { ftp.openbsd.org }\en \e
\  \  pass out to <test> keep state\en" \&| pfctl -f-
# ping -qc10 ftp.openbsd.org
.Ed
.Pp
We can now use the table
.Ar show
command to output, for each address and packet direction, the number of packets
and bytes that are being passed or blocked by rules referencing the table.
The time at which the current accounting started is also shown with the
.Ar Cleared
line.
.Bd -literal -offset indent
# pfctl -t test -vTshow
\ \ \ 129.128.5.191
\ \ \ \ Cleared: \ \ \ \ Thu Feb 13 18:55:18 2003
\ \ \ \ In/Block: \ \ \ [ Packets: 0 \ \ \ \ \ \ \ Bytes: 0 \ \ \ \ \ \ \ ]
\ \ \ \ In/Pass: \ \ \ \ [ Packets: 10 \ \ \ \ \ \ Bytes: 840 \ \ \ \ \ ]
\ \ \ \ Out/Block: \ \ [ Packets: 0 \ \ \ \ \ \ \ Bytes: 0 \ \ \ \ \ \ \ ]
\ \ \ \ Out/Pass: \ \ \ [ Packets: 10 \ \ \ \ \ \ Bytes: 840 \ \ \ \ \ ]
.Ed
.Pp
Similarly, it is possible to view global information about the tables
by using the
.Fl v
modifier twice and the
.Ar show Tables
command.
This will display the number of addresses on each table,
the number of rules which reference the table, and the global
packet statistics for the whole table:
.Bd -literal -offset indent
# pfctl -vvsTables
--a-r-  test
\ \ \ \ Addresses: \ \ 1
\ \ \ \ Cleared: \ \ \ \ Thu Feb 13 18:55:18 2003
\ \ \ \ References: \ [ Anchors: 0 \ \ \ \ \ \ \ Rules: 1 \ \ \ \ \ \ \ ]
\ \ \ \ Evaluations: [ NoMatch: 3496 \ \ \ \ Match: 1 \ \ \ \ \ \ \ ]
\ \ \ \ In/Block: \ \ \ [ Packets: 0 \ \ \ \ \ \ \ Bytes: 0 \ \ \ \ \ \ \ ]
\ \ \ \ In/Pass: \ \ \ \ [ Packets: 10 \ \ \ \ \ \ Bytes: 840 \ \ \ \ \ ]
\ \ \ \ In/XPass: \ \ \ [ Packets: 0 \ \ \ \ \ \ \ Bytes: 0 \ \ \ \ \ \ \ ]
\ \ \ \ Out/Block: \ \ [ Packets: 0 \ \ \ \ \ \ \ Bytes: 0 \ \ \ \ \ \ \ ]
\ \ \ \ Out/Pass: \ \ \ [ Packets: 10 \ \ \ \ \ \ Bytes: 840 \ \ \ \ \ ]
\ \ \ \ Out/XPass: \ \ [ Packets: 0 \ \ \ \ \ \ \ Bytes: 0 \ \ \ \ \ \ \ ]
.Ed
.Pp
As we can see here, only one packet - the initial ping request - matched the
table; but all packets passing as the result of the state are correctly
accounted for.
Reloading the table(s) or ruleset will not affect packet accounting in any way.
The two
.Ar XPass
counters are incremented instead of the
.Ar Pass
counters when a \&"stateful\&" packet is passed but doesn't match the table
anymore.
This will happen in our example if someone flushes the table while the ping
command is running.
.Pp
When used with a single
.Fl v ,
.Nm pfctl
will only display the first line containing the table flags and name.
The flags are defined as follows:
.Pp
.Bl -tag -width XXX -compact
.It c
For constant tables, which cannot be altered outside
.Xr pf.conf 5 .
.It p
For persistent tables, which don't get automatically flushed when no rules
refer to them.
.It a
For tables which are part of the
.Ar active
tableset.
Tables without this flag do not really exist, cannot contain addresses, and are
only listed if the
.Fl g
flag is given.
.It i
For tables which are part of the
.Ar inactive
tableset.
This flag can only be witnessed briefly during the loading of
.Xr pf.conf 5 .
.It r
For tables which are referenced (used) by rules.
.It h
This flag is set when a table in the main ruleset is hidden by one or more
tables of the same name in sub-rulesets (anchors).
.El
.It Fl v
Produce more verbose output.
A second use of
.Fl v
will produce even more verbose output including ruleset warnings.
See previous section for its effect on table commands.
.It Fl x Ar level
Set the debug
.Ar level
(may be abbreviated) to one of the following:
.Bl -tag -width xxxxxxxxxxxx -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.
.It Fl x Ar loud
Generate debug messages for common conditions.
.El
.It Fl z
Clear per-rule statistics.
.El
.Sh FILES
.Bl -tag -width "/etc/pf.conf" -compact
.It Pa /etc/pf.conf
Packet filter rules file.
.El
.Sh SEE ALSO
.Xr pf 4 ,
.Xr pf.conf 5 ,
.Xr pf.os 5
.Xr sysctl.conf 5 ,
.Xr ftp-proxy 8 ,
.Xr rc 8 ,
.Xr rc.conf 8 ,
.Xr sysctl 8
.Sh HISTORY
The
.Nm
program and the
.Xr pf 4
filter mechanism first appeared in
.Ox 3.0 .