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

 

NAME

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

SYNOPSIS

      pfctl [-AdeghmNnOqRrvz] [-a anchor] [-D macro= value] [-F modifier]
            [-f file] [-i interface] [-K host | network] [-k host | network]
            [-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 con‐
      figuration 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 con‐
      nect 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(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 anchors.  The main
              ruleset is the default anchor.
 
              Anchors are referenced by name and may be nested, with the vari‐
              ous 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 per‐
              formed.
 
              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 cre‐
              ate 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 recur‐
              sively 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
 
      -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 abbre‐
              viated):
 
              -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 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
              Kill all of the state entries originating from the specified host
              or network.  A second -k host or -k network option may be speci‐
              fied, which will kill all the state entries from the first
              host/network to the second.  For example, to kill all of the
              state entries originating from “host”:
 
                    # pfctl -k host
 
              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
 
      -m      Merge in explicitly given options without resetting those which
              are omitted.  Allows single options to be modified without dis‐
              turbing 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.  The ruleset optimizer attempts to
              improve rulesets by removing rule duplication and making better
              use of rule ordering.
 
              -o none       Disable the ruleset optimizer.
              -o basic      Enable basic ruleset optimizations.
              -o profile    Enable basic ruleset optimizations with profiling.
 
              basic optimization does 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 advantageous
              4.   re-order the rules to improve evaluation performance
 
              If profile is specified, the currently loaded ruleset will be
              examined 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 accounting is impor‐
              tant for billing purposes or whatnot, either the ruleset opti‐
              mizer should not be used or a label field should be added to all
              of the accounting rules to act as optimization barriers.
 
              To retain compatibility with previous behaviour, a single -o
              without any options will enable basic optimizations, and a second
              -o will enable profiling.
 
      -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 abbrevi‐
              ated):
 
              -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 auto‐
                             matically 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 tar‐
                             get anchor will be displayed recursively.
              -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 total, bytes total, packets in, bytes in,
                             packets out, bytes out) 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 inter‐
                             faces.
              -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.  Automati‐
                            cally 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:
 
                                  # 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 operation for
              each individual address, prefixed by one of the following let‐
              ters:
 
              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 (statistics).
 
              Each table maintains 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> { 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 num‐
              ber 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 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.
 
      -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.
      pf(4), pf.conf(5), pf.os(5), rc.conf(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.
 

Sections

Based on BSD UNIX
FreeBSD is an advanced operating system for x86 compatible (including Pentium and Athlon), amd64 compatible (including Opteron, Athlon64, and EM64T), UltraSPARC, IA-64, PC-98 and ARM architectures. It is derived from BSD, the version of UNIX developed at the University of California, Berkeley. It is developed and maintained by a large team of individuals. Additional platforms are in various stages of development.