NAME¶
pfctl —
control the packet filter (PF)
device
SYNOPSIS¶
pfctl |
[-AdeghmNnOPqRrvz]
[-a anchor]
[-D macro= value]
[-F modifier]
[-f file]
[-i interface]
[-K host | network]
[-k host
| network | label | id]
[-o level]
[-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 different hosts and/or ports. A combination of both
translations, bidirectional NAT, is also supported. Translation rules are
described in
pf.conf(5).
When the variable
pf is set to
YES
in
rc.conf.local(8), 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 anchors. 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 operations 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, either 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 anchor, 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.
By default, recursive inline printing of anchors applies only to unnamed
anchors specified inline in the ruleset. If the anchor name is terminated
with a ‘*’ character, the -s flag will
recursively print all anchors in a brace delimited block. For example the
following will print the “authpf” ruleset recursively:
# pfctl -a 'authpf/*' -sr
To print the main ruleset recursively, specify only ‘*’ as the
anchor name:
- -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
states
- Flush the state table (NAT and filter).
- -F
Sources
- Flush the source tracking table.
- -F
info
- Flush the filter information (statistics 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, translation, 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 | network
- Kill all of the source tracking entries originating from
the specified host or network.
A second -K host or
-K network option may be
specified, which will kill all the source tracking entries from the first
host/network to the second.
- -k
host | network |
label | id
- Kill all of the state entries matching the specified
host, network,
label, or id.
For example, to kill all of the state entries originating from
“host”:
# pfctl -k host
A second -k host or
-k network option may be
specified, which will kill all the state entries from the first
host/network to the second. To kill all of the state entries from
“host1” to “host2”:
# pfctl -k host1 -k host2
To kill all states originating from 192.168.1.0/24 to 172.16.0.0/16:
# pfctl -k 192.168.1.0/24 -k
172.16.0.0/16
A network prefix length of 0 can be used as a wildcard. To kill all states
with the target “host2”:
# pfctl -k 0.0.0.0/0 -k host2
It is also possible to kill states by rule label or state ID. In this mode
the first -k argument is used to specify the type of the
second argument. The following command would kill all states that have
been created from rules carrying the label “foobar”:
# pfctl -k label -k foobar
To kill one specific state by its unique state ID (as shown by pfctl -s
state -vv), use the id modifier and as a second
argument the state ID and optional creator ID. To kill a state with ID
4823e84500000003 use:
# pfctl -k id -k
4823e84500000003
To kill a state with ID 4823e84500000018 created from a backup firewall with
hostid 00000002 use:
# pfctl -k id -k
4823e84500000018/2
- -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
level
- Control the ruleset optimizer, overriding any rule file
settings.
- -o
none
- Disable the ruleset optimizer.
- -o
basic
- Enable basic ruleset optimizations. This is the default
behaviour.
- -o
profile
- Enable basic ruleset optimizations with profiling.
For further information on the ruleset optimizer, see
pf.conf(5).
- -P
- Do not perform service name lookup for port specific rules,
instead display the ports numerically.
- -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 displaying
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 used
together with -v, per-queue statistics are also
shown. When used together with -v
-v, pfctl will loop and show
updated queue statistics 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” 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).
- -s
Anchors
- Show the currently loaded anchors directly attached to
the main ruleset. If -a anchor
is specified as well, the anchors loaded directly below the given
anchor are shown instead. If
-v is specified, all anchors attached under the
target anchor will be displayed recursively.
- -s
states
- 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
total, bytes total, packets in, bytes in, packets out, bytes out,
state creations) 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 interface drivers
available to PF. When used together with -v, it
additionally lists which interfaces have skip rules activated. When
used together with -vv, 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 of
interfaces and operating system fingerprints.
- -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. Automatically
create a nonexisting table.
- -T
delete
- Delete one or more addresses from a table.
- -T
expire number
- Delete addresses which had their statistics cleared
more than number seconds ago. For entries which
have never had their statistics cleared, number
refers to the time they were added to the 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:
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
operation for each individual address, prefixed by one of the following
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
conflicting ‘!’ attributes.
- Z
- The address/network has been cleared (statistics).
Each table can maintain a set of counters that can be retrieved using the
-v flag of pfctl. For example, the
following 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> counters { ftp.openbsd.org }\n \
pass out to <test>\n" | 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 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:
# pfctl -vvsTables
--a-r-C 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 running.
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 automatically
killed when no rules refer to them.
- a
- For tables which are part of the
active tableset. 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 tableset. 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 ruleset is
hidden by one or more tables of the same name from anchors attached
below it.
- C
- This flag is set when per-address counters are enabled
on the table.
- -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 serious 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),
services(5),
sysctl.conf(5),
authpf(8),
ftp-proxy(8),
rc(8),
sysctl(8)
HISTORY¶
The
pfctl program and the
pf(4) filter
mechanism first appeared in
OpenBSD 3.0.