bionic (5) firehol-action4.5.gz

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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.