pfctl(8)

NAME

pfctl - control the packet filter (PF) and network address

translation
(NAT) device

SYNOPSIS

pfctl  [-AdeghmNnOoqRrvz]  [-a  anchor] [-D macro=value] [-F
modifier]
      [-f file] [-i interface] [-k  host]  [-p  device]  [-s
modifier] [-t
      table -T command [address ...]] [-x level]

DESCRIPTION

The pfctl utility communicates with the packet filter device

using the
ioctl interface described in pf(4). It allows ruleset and

parameter configuration and retrieval of status information from the

packet filter.

Packet filtering restricts the types of packets that pass

through network
interfaces entering or leaving the host based on filter

rules as
described in 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 differ

ent hosts
and/or ports. A combination of both translations, bidirec

tional NAT, is
also supported. Translation rules are described in

pf.conf(5).

When the variable pf is set to YES in rc.conf.local(5), the

rule file
specified with the variable pf_rules is loaded automatically

by the rc(8)
scripts and the packet filter is enabled.

The packet filter does not itself forward packets between

interfaces.
Forwarding can be enabled by setting the sysctl(8) variables
net.inet.ip.forwarding and/or net.inet6.ip6.forwarding to 1.

Set them
permanently in sysctl.conf(5).

The pfctl utility provides several commands. The options

are as follows:

-A Load only the queue rules present in the rule file.

Other rules

and options are ignored.

-a anchor

Apply flags -f, -F, and -s only to the rules in the

specified
anchor. In addition to the main ruleset, pfctl can

load and
manipulate additional rulesets by name, called an

chors. The main
ruleset is the default anchor.

Anchors are referenced by name and may be nested,

with the various components of the anchor path separated by `/'

characters,
similar to how file system hierarchies are laid out.

The last
component of the anchor path is where ruleset opera

tions are performed.

Evaluation of anchor rules from the main ruleset is

described in
pf.conf(5).

For example, the following will show all filter

rules (see the -s
flag below) inside the anchor authpf/smith(1234),

which would
have been created for user smith by authpf(8), PID

1234:

# pfctl -a "authpf/smith(1234)" -s rules

Private tables can also be put inside anchors, ei

ther by having
table statements in the pf.conf(5) file that is

loaded in the
anchor, or by using regular table commands, as in:

# pfctl -a foo/bar -t mytable -T add 1.2.3.4

5.6.7.8

When a rule referring to a table is loaded in an an

chor, the rule
will use the private table if one is defined, and

then fall back
to the table defined in the main ruleset, if there

is one. This
is similar to C rules for variable scope. It is

possible to create distinct tables with the same name in the global

ruleset and
in an anchor, but this is often bad design and a

warning will be
issued in that case.

-D macro=value

Define macro to be set to value on the command line.

Overrides
the definition of macro in the ruleset.

-d Disable the packet filter.

-e Enable the packet filter.

-F modifier

Flush the filter parameters specified by modifier

(may be abbreviated):

-F nat Flush the NAT rules.
-F queue Flush the queue rules.
-F rules Flush the filter rules.
-F state Flush the state table (NAT and fil

ter).
-F Sources Flush the source tracking table. -F info Flush the filter information (statis

tics that are

not bound to rules).

-F Tables Flush the tables.
-F osfp Flush the passive operating system

fingerprints.
-F all Flush all of the above.

-f file

Load the rules contained in file. This file may

contain macros,
tables, options, and normalization, queueing, trans

lation, and
filtering rules. With the exception of macros and

tables, the
statements must appear in that order.

-g Include output helpful for debugging.

-h Help.

-i interface

Restrict the operation to the given interface.

-k host

Kill all of the state entries originating from the

specified
host. A second -k host option may be specified,

which will kill
all the state entries from the first host to the

second host.
For example, to kill all of the state entries origi

nating from
host:

# pfctl -k host

To kill all of the state entries from host1 to

host2:

# pfctl -k host1 -k host2

-m Merge in explicitly given options without resetting

those which

are omitted. Allows single options to be modified

without disturbing the others:

# echo "set loginterface fxp0" | pfctl -mf

-N Load only the NAT rules present in the rule file.

Other rules

and options are ignored.

-n Do not actually load rules, just parse them.

-O Load only the options present in the rule file.

Other rules and

options are ignored.

-o Enable the ruleset optimizer. The ruleset optimizer

attempts to

improve rulesets by removing rule duplication and

making better
use of rule ordering. Specifically, it does four

things:

1. remove duplicate rules
2. remove rules that are a subset of another rule
3. combine multiple rules into a table when advan

tageous
4. re-order the rules to improve evaluation per

formance

A second -o may be specified to use the currently

loaded ruleset
as a feedback profile to tailor the optimization of

the quick
rules to the actual network behavior.

It is important to note that the ruleset optimizer

will modify
the ruleset to improve performance. A side effect

of the ruleset
modification is that per-rule accounting statistics

will have
different meanings than before. If per-rule ac

counting is important for billing purposes or whatnot, either the

ruleset optimizer should not be used or a label field should be

added to all
of the accounting rules to act as optimization bar

riers.

-p device
Use the device file device instead of the default

/dev/pf.

-q Only print errors and warnings.

-R Load only the filter rules present in the rule file.

Other rules
and options are ignored.

-r Perform reverse DNS lookups on states when display

ing them.

-s modifier
Show the filter parameters specified by modifier

(may be abbreviated):

-s nat Show the currently loaded NAT rules.
-s queue Show the currently loaded queue

rules. When usedtogether with -v, per-queue statis

tics are also
shown. When used together with -v

-v, pfctl will
loop and show updated queue statis

tics every five
seconds, including measured bandwidth

and packets
per second.

-s 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'' optimiza

tion 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).

-s Anchors Show the currently loaded anchors di

rectly
attached to the main ruleset. If -a

anchor is
specified as well, the anchors loaded

directly
below the given anchor are shown in

stead. If -v
is specified, all anchors attached

under the target anchor will be displayed recur

sively.

-s state Show the contents of the state table. -s Sources Show the contents of the source

tracking table.
-s info Show filter information (statistics

and counters).
When used together with -v, source

tracking
statistics are also shown.

-s labels Show per-rule statistics (label,

evaluations,
packets, bytes) of filter rules with

labels, useful for accounting.

-s timeouts Show the current global timeouts. -s memory Show the current pool memory hard

limits.
-s Tables Show the list of tables.
-s osfp Show the list of operating system

fingerprints.
-s Interfaces Show the list of interfaces and in

terface drivers
available to PF. When used together

with a double
-v, interface statistics are also

shown. -i can
be used to select an interface or a

group of
interfaces.

-s all Show all of the above, except for the

lists ofinterfaces and operating system fin

gerprints.

-T command [address ...]
Specify the command (may be abbreviated) to apply to

the table.
Commands include:

-T kill Kill a table.
-T flush Flush all addresses of a table.
-T add Add one or more addresses in a table.

Automati
cally create a nonexisting table.

-T delete Delete one or more addresses from a

table.
-T replace Replace the addresses of the table.

Automatically
create a nonexisting table.

-T show Show the content (addresses) of a

table.
-T test Test if the given addresses match a

table.
-T zero Clear all the statistics of a table.
-T load Load only the table definitions from

pf.conf(5).
This is used in conjunction with the

-f flag, as
in:

# pfctl -Tl -f pf.conf

For the add, delete, replace, and test commands, the

list of
addresses can be specified either directly on the

command line
and/or in an unformatted text file, using the -f

flag. Comments
starting with a `#' are allowed in the text file.

With these
commands, the -v flag can also be used once or

twice, in which
case pfctl will print the detailed result of the op

eration for
each individual address, prefixed by one of the fol

lowing letters:

A The address/network has been added.
C The address/network has been changed (negated).
D The address/network has been deleted.
M The address matches (test operation only).
X The address/network is duplicated and therefore

ignored.
Y The address/network cannot be added/deleted due

to conflict
ing `!' attributes.

Z The address/network has been cleared (statis

tics).

Each table maintains a set of counters that can be

retrieved
using the -v flag of pfctl. For example, the fol

lowing commands
define a wide open firewall which will keep track of

packets
going to or coming from the OpenBSD FTP server. The

following
commands configure the firewall and send 10 pings to

the FTP
server:

# printf "table <test> { ftp.openbsd.org }

pass out to <test> keep state0 | pfctl -f# ping -qc10 ftp.openbsd.org

We can now use the table 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
``Cleared'' line.

# 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 ]

Similarly, it is possible to view global information

about the
tables by using the -v modifier twice and the -s

Tables

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:

# 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

]

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
``XPass'' counters are incremented instead of the

``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(8) command is run

ning.

When used with a single -v, pfctl will only display

the first
line containing the table flags and name. The flags

are defined
as follows:

c For constant tables, which cannot be altered

outside
pf.conf(5).

p For persistent tables, which don't get automat

ically killed
when no rules refer to them.

a For tables which are part of the active table

set. Tables
without this flag do not really exist, cannot

contain
addresses, and are only listed if the -g flag

is given.

i For tables which are part of the inactive ta

bleset. This
flag can only be witnessed briefly during the

loading of
pf.conf(5).

r For tables which are referenced (used) by

rules.
h This flag is set when a table in the main rule

set is hiddenby one or more tables of the same name from an

chors attached
below it.

-t table
Specify the name of the table.

-v Produce more verbose output. A second use of -v

will produce
even more verbose output including ruleset warnings.

See the
previous section for its effect on table commands.

-x level
Set the debug level (may be abbreviated) to one of

the following:

-x none Don't generate debug messages.
-x urgent Generate debug messages only for seri

ous errors.
-x misc Generate debug messages for various

errors.
-x loud Generate debug messages for common

conditions.

-z Clear per-rule statistics.

FILES

/etc/pf.conf Packet filter rules file.
/etc/pf.os Passive operating system fingerprint database.

SEE ALSO

pf(4), pf.conf(5), pf.os(5), rc.conf(5), sysctl.conf(5), au

thpf(8),
ftp-proxy(8), rc(8), sysctl(8)

HISTORY

The pfctl program and the pf(4) filter mechanism first ap

peared in
OpenBSD 3.0.

BSD November 20, 2002

BSD