PFCTL(8) | System Manager's Manual | PFCTL(8) |
pfctl
— control
the packet filter (PF) device
pfctl |
[-deghNnPqrvz ]
[-a anchor]
[-D macro=value]
[-F modifier]
[-f file]
[-i interface]
[-K key]
[-k key]
[-L statefile]
[-o level]
[-p device]
[-S statefile]
[-s modifier [-R id]]
[-t table -T command [address ...]]
[-V rdomain]
[-x level] |
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.
The packet filter is enabled by default. Should
pfctl
be unable to load a ruleset, an error occurs
and the original ruleset remains in place. If this happens at system
startup, the ruleset defined by the RULES variable in
rc(8) remains in place.
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).
At least one option must be specified. The options are as follows:
-a
anchor-f
, -F
,
-s
, and -T
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:
# pfctl -a '*' -sr
To flush all rulesets and tables recursively, specify only ‘*’ as the anchor name:
# pfctl -a '*' -Fa
-D
macro=value-d
-e
-F
modifier-F
rules
-F
states
-F
Sources
-F
info
-F
Tables
-F
osfp
-F
Reset
-F
all
If -a
is specified as well and
anchor is terminated with a ‘*’
character, rules
, Tables
and all
flush the given anchor recursively.
-f
file-g
-h
-i
interface-K
key-K
option may be specified, which will kill all
the source tracking entries from the first host/network to the
second.-k
key-k
option may be specified, which will kill all
the state entries from the first host/network to the second.
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, state key,
or state ID. In this mode the first -k
argument
is used to specify the type; a second -k
gives
the actual target.
To kill states by rule label, use the
label
modifier. To kill all states created from
rules carrying the label “foobar”:
# pfctl -k label -k
foobar
To kill one specific state by its state key (as shown by pfctl
-s state), use the key
modifier. To kill a state
originating from 10.0.0.101:32123 to 10.0.0.1:80, protocol TCP, use:
# pfctl -k key -k 'tcp
10.0.0.1:80 <- 10.0.0.101:32123'
To kill one specific state by its unique state ID (as shown by
pfctl -s state -vv), use the id
modifier. 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
-L
statefile-N
-n
-o
level-o
none
-o
basic
-o
profile
-P
-p
device-q
-r
-N
and -r
are mutually
exclusive.-S
statefile-s
modifier-s
queue
-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
-R
id is specified as well, only the rule with the
specified numeric ID is shown. 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
-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
-R
id is specified as well, only states created by
the rule with the specified numeric ID are shown.-s
Sources
-s
info
-v
, source tracking statistics, the
firewall's 32-bit hostid number and the main ruleset's MD5 checksum
for use with pfsync(4)
are also shown.-s
labels
-R
id is specified as
well, only the statistics for the rule with the specified numeric ID
are shown.-s
timeouts
-s
memory
-s
Tables
-s
osfp
-s
Interfaces
-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
Counters shown with -s
info
are:
-T
command [address ...]-T
kill
-T
flush
-T
add
-T
delete
-T
expire
number-T
replace
-T
show
-T
test
-T
zero
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:
test
operation
only).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, matched or blocked by rules referencing
the table. Note that the match counters are incremented for every match
rule in which they are referenced, meaning that a single packet may be
counted multiple times. The time at which the current accounting started
is also shown with the “Cleared” line.
# pfctl -t test -vTshow 198.51.100.81 Cleared: Fri Jun 28 11:17:37 2013 In/Block: [ Packets: 0 Bytes: 0 ] In/Match [ Packets: 54 Bytes: 10028 ] In/Pass: [ Packets: 5 Bytes: 1949 ] Out/Block: [ Packets: 0 Bytes: 0 ] Out/Match [ Packets: 65 Bytes: 12684 ] Out/Pass: [ Packets: 6 Bytes: 389 ]
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: Fri Jun 28 11:17:37 2013 References: [ Anchors: 0 Rules: 4 ] Evaluations: [ NoMatch: 35 Match: 8 ] In/Block: [ Packets: 0 Bytes: 0 ] In/Match: [ Packets: 54 Bytes: 10028 ] In/Pass: [ Packets: 5 Bytes: 1949 ] In/XPass: [ Packets: 0 Bytes: 0 ] Out/Block: [ Packets: 0 Bytes: 0 ] Out/Match: [ Packets: 65 Bytes: 12684 ] Out/Pass: [ Packets: 6 Bytes: 389 ] Out/XPass: [ Packets: 0 Bytes: 0 ]
Only packets creating state are matched in the Evaluations line, but all packets passing as a 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:
-g
flag
is given.-t
table-V
rdomain-s
states
.-v
-v
will produce even more verbose output including ruleset warnings. See the
previous section for its effect on table commands.-x
levelemerg
, alert
,
crit
, err
,
warning
, notice
,
info
, and debug
. These
keywords correspond to the similar (LOG_) values specified to the
syslog(3) library routine,
and may be abbreviated on the command line.-z
pf(4), pf.conf(5), pf.os(5), sysctl.conf(5), authpf(8), ftp-proxy(8), rc(8), rc.conf(8), sysctl(8)
The pfctl
program and the
pf(4) filter mechanism first
appeared in OpenBSD 3.0.
July 20, 2020 | OpenBSD-6.8 |