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NAME

       firehol-action - set up custom filtering actions

SYNOPSIS

       action name [table table_name] type type_params [ next [ type type_params [ next ... ] ] ]

DESCRIPTION

       The  action  helper  creates  custom  actions that can be used everywhere in FireHOL, like
       this:

              action ACT1 chain accept

              interface any world
                  server smtp ACT1

              router myrouter
                  policy ACT1

       The action helper allows linking multiple actions together and having some logic to select
       which action to execute, like this:

              action ACT1 \
                       rule src 192.168.0.0/16 action reject \
                  next rule dst 192.168.0.0/16 action reject \
                  next rule inface eth2 action drop \
                  next rule outface eth2 action drop \
                  next action accept

              interface any world
                  server smtp ACT1

              router myrouter
                  policy ACT1

       There is no limit on the number of actions that can be linked together.

       type  can  be  chain  or  action (chain and action are aliases), rule, iptrap, ipuntrap or
       sockets_suspects_trap.

   Chain type actions
       This is the simpler action.  It creates an iptables(8) chain which can be used to  control
       the action of other firewall rules once the firewall is running.

       For  example, you can setup the custom action ACT1, which by default is ACCEPT, but can be
       dynamically changed to DROP, REJECT or RETURN (and back) without restarting the firewall.

       The name can be any chain name accepted by iptables.  You should try to keep it  within  5
       and 10 characters.

              Note

              The names created with this command are case-sensitive.

       The  action  can  be  any  of  those  supported by FireHOL (see firehol-actions(5)).  Only
       ACCEPT, REJECT, DROP, RETURN have any meaning in this instance.

       Once the firewall is running you can dynamically modify the behaviour of  the  chain  from
       the Linux command-line, as detailed below:

              action ACT1 chain accept

              interface any world
                  server smtp ACT1
                  client smtp ACT1

       To insert a DROP action at the start of the chain to override the default action (ACCEPT):

              iptables -t filter -I ACT1 -j DROP

       To delete the DROP action from the start of the chain to return to the default action:

              iptables -t filter -D ACT1 -j DROP

              Note

              If  you  delete  all  of  the rules in the chain, the default will be to RETURN, in
              which case the behaviour will be as if any rules with the action were  not  present
              in the configuration file.

   Rule type actions
       rule type actions define a few conditions that will lead to an action.

       All optional rule parameters FireHOL supports can be used here (see firehol-params(5)).

              action ACT1 \
                  rule inface eth0 action accept
                  next rule outface eth0 action accept
                  next action reject

              interface any world
                  server smtp ACT1

       In the above example the smtp server can only be accessed from eth0.

       It  is  important  to  remember  that  actions  will  be applied for all the traffic, both
       requests and replies.  The type of traffic can be filtered with the  state  optional  rule
       parameter, like this:

              action ACT1 \
                  rule inface eth0 state NEW action reject
                  next action accept

              interface any world
                  server smtp ACT1
                  client smtp ACT1

       In  the  above example, the smtp server will not accept NEW connections from eth0, but the
       smtp client will be able to connect to servers on eth0 (and everywhere else).

   iptrap type actions
       iptrap (see [firehol-iptrap(5)][]) is a helper than copies (traps) an IP to an ipset  (see
       [firehol-ipset(5)][]).  It does not perform any action on the traffic.

       Using the iptrap action, the iptrap helper can be linked to filtering actions, like this:

               # a simple version of TRAP_AND_REJECT
               # this uses just 2 ipsets, one for counting packets (policytrap)
               # and one to store the banned IPs (trap).
               # it also needs a ipset called whitelist, for excluded source IPs.
               # it will ban IPs when they have 50+ reject packets
               action4 TRAP_AND_REJECT \
                  rule iptrap src policytrap 30 inface "${wan}" \
                      src not "${UNROUTABLE_IPS} ipset:whitelist" \
                      state NEW log "POLICY TRAP" \
                  next iptrap trap src 86400 \
                      state NEW log "POLICY TRAP - BANNED" \
                      ipset policytrap src no-counters packets-above 50 \
                  next action reject

               # a complete TRAP_AND_REJECT
               # this uses 3 ipset, one for keeping track of the rejected sockets
               # per source IP (called 'sockets'), one for counting the sockets
               # per source IP (called 'suspects') and one to store the banned IPs
               # (called 'trap').
               # it also needs a ipset called whitelist, for excluded source IPs.
               # it will ban IPs when they have 3 or more rejected sockets
               action4 TRAP_AND_REJECT \
                  iptrap sockets src,dst,dst 3600 method hash:ip,port,ip counters \
                      state NEW log "TRAP AND REJECT - NEW SOCKET" \
                      inface "${wan}" \
                      src not "${UNROUTABLE_IPS} ipset:whitelist" \
                  next iptrap suspects src 3600 counters \
                      state NEW log "TRAP AND REJECT - NEW SUSPECT" \
                      ipset sockets src,dst,dst no-counters packets 1 \
                  next iptrap trap src 86400 \
                      state NEW log "TRAP AND REJECT - BANNED" \
                      ipset suspects src no-counters packets-above 2 \
                  next action REJECT

               interface any world
                  policy TRAP_AND_REJECT
                  protection bad-packets
                  ...

               router wan2lan inface "${wan}" outface "${lan}"
                  policy TRAP_AND_REJECT
                  protection bad-packets
                  ...

       Since  we  used  the  action  TRAP_AND_REJECT  as an interface policy, it will get all the
       traffic not accepted, rejected, or dropped by the server and client statements.

       For all these packets, the action TRAP_AND_REJECT will first check that they are coming in
       from  wan0,  that  their  src IP is not in UNROUTABLE_IPS list and in the whitelist ipset,
       that they are NEW connections, and if all these conditions are met, it will log  with  the
       tag POLICY TRAP and add the src IP of the packets in the policytrap ipset for 30 seconds.

       All traffic not matched by the above, will be just rejected.

   sockets_suspects_trap type actions
       The  type  sockets_suspects_trap  will  automatically  a  custom  trap using the following
       template:

              action4 *name* sockets_suspects_trap *SUSPECTS_TIMEOUT* *TRAP_TIMEOUT* *VALID_CONNECTIONS* [*optional params*] next ...

       This will:

       1. Create the  ipset  ${name}_sockets  where  the  matched  sockets  will  be  stored  for
          SUSPECTS_TIMEOUT seconds.

       2. Create  the  ipset ${name}_suspects where the source IPs of the matched sockets will be
          stored for SUSPECTS_TIMEOUT seconds.

       3. Create the ipset ${name}_trap where the trapped IPs will  be  stored  for  TRAP_TIMEOUT
          seconds.  IPs will be added to this ipset only if more than VALID_CONNECTIONS have been
          matched by this IP.

       optional params are FireHOL optional rule parameters (firehol-params(5)) that can be  used
       to limit the match for the first ipset (sockets).

       So, to design the same TRAP_AND_REJECT as above, this statement is needed:

              action4 TRAP_AND_REJECT \
                  sockets_suspects_trap 3600 86400 2 \
                      inface "${wan}" \
                      src not "${UNROUTABLE_IPS} ipset:whitelist" \
                  next action REJECT

       The    ipsets   that   will   be   created   will   be   named:   TRAP_AND_REJECT_sockets,
       TRAP_AND_REJECT_suspects and TRAP_AND_REJECT_trap.

              Note Always terminate sockets_suspects_trap with a next action DROP or next  action
              REJECT, or the traffic will continue to flow.

SEE ALSO

firehol(1) - FireHOL program

       • firehol.conf(5) - FireHOL configuration

       • firehol-actions(5) - optional rule parameters

       • iptables(8)  (http://ipset.netfilter.org/iptables.man.html)  -  administration  tool for
         IPv4 firewalls

       • ip6tables(8) (http://ipset.netfilter.org/ip6tables.man.html) - administration  tool  for
         IPv6 firewalls

       • FireHOL Website (http://firehol.org/)

       • FireHOL Online PDF Manual (http://firehol.org/firehol-manual.pdf)

       • FireHOL Online Documentation (http://firehol.org/documentation/)

AUTHORS

       FireHOL Team.