FIREHOL-ACTIONS - reference manual online
Actions for rules.
Built 06 May 2015
firehol-actions(5) 2.0.3 firehol-actions(5)
NAME firehol-actions - actions for rules SYNOPSIS accept accept with limit requests/period burst [overflow action] accept with recent name seconds hits accept with knock name reject [with message] drop | deny return tarpit DESCRIPTION These actions are the actions to be taken on traffic that has been matched by a particular rule. FireHOL will also pass through any actions that iptables(8) accepts, however these definitions provide lowercase versions which accept arguments where appropriate and which could otherwise not be passed through. Note The iptables(8) LOG action is best used through the optional rule parameter log since the latter can be combined with one of these actions (FireHOL will generate multiple firewall rules to make this happen). For more information see log and loglimit. The following actions are defined: accept accept allows the traffic matching the rules to reach its destination. For example, to allow SMTP requests and their replies to flow: server smtp accept accept with limit requests/period burst [overflow action] accept with limit allows the traffic, with new connections limited to requests/period with a maximum burst. Run iptables -m limit --help for more information. The default overflow action is to REJECT the excess connections (DROP would produce timeouts on otherwise valid service clients). Examples: server smtp accept with limit 10/sec 100 server smtp accept with limit 10/sec 100 overflow drop accept with recent name seconds hits accept with recent allows the traffic matching the rules to reach its destination, limited per remote IP to hits per seconds. Run iptables -m recent --help for more information. The name parameter is used to allow multiple rules to share the same table of recent IPs. For example, to allow only 2 connections every 60 seconds per remote IP, to the smtp server: server smtp accept with recent mail 60 2 Note When a new connection is not allowed, the traffic will continue to be matched by the rest of the firewall. In other words, if the traffic is not allowed due to the limitations set here, it is not dropped, it is just not matched by this rule. accept with knock name accept with knock allows easy integration with knockd (http://www.zeroflux.org/knock/), a server that allows you to control access to services by sending certain packets to "knock" on the door, before the door is opened for service. The name is used to build a special chain knock_<name> which contains rules to allow established connections to work. If knockd has not allowed new connections any traffic entering this chain will just return back and continue to match against the other rules until the end of the firewall. For example, to allow HTTPS requests based on a knock write: server https accept with knock hidden then configure knockd to enable the HTTPS service with: iptables -A knock_hidden -s %IP% -j ACCEPT and disable it with: iptables -D knock_hidden -s %IP% -j ACCEPT You can use the same knock name in more than one FireHOL rule to enable/disable all the services based on a single knockd configuration entry. Note There is no need to match anything other than the IP in knockd. FireHOL already matches everything else needed for its rules to work. reject reject discards the traffic matching the rules and sends a rejecting message back to the sender. reject with message When used with with the specific message to return can be specified. Run iptables -j REJECT --help for a list of the --reject-with values which can be used for message. See REJECT WITH MESSAGES for some examples. The default (no message specified) is to send tcp-reset when dealing with TCP connections and icmp-port-unreachable for all other protocols. For example: UNMATCHED_INPUT_POLICY="reject with host-prohib" policy reject with host-unreach server ident reject with tcp-reset drop; deny drop discards the traffic matching the rules. It does so silently and the sender will need to timeout to conclude it cannot reach the service. deny is a synonym for drop. For example, either of these would silently discard SMTP traffic: server smtp drop server smtp deny return return will return the flow of processing to the parent of the current command. Currently, the only time return can be used meaningfully used is as a policy for an interface definition. Unmatched traffic will continue being processed with the possibility of being matched by a later definition. For example: policy return tarpit tarpit captures and holds incoming TCP connections open. Connections are accepted and immediately switched to the persist state (0 byte window), in which the remote side stops sending data and asks to continue every 60-240 seconds. Attempts to close the connection are ignored, forcing the remote side to time out the connection after 12-24 minutes. Example: server smtp tarpit Note As the kernel conntrack modules are always loaded by FireHOL, some per-connection resources will be consumed. See this bug report (http://bugs.sanewall.org/sanewall/issues/10) for details. The following actions also exist but should not be used under normal circumstances: mirror mirror returns the traffic it receives by switching the source and destination fields. REJECT will be used for traffic generated by the local host. Warning The MIRROR target was removed from the Linux kernel due to its security implications. MIRROR is dangerous; use it with care and only if you understand what you are doing. redirect; redirect to-port port redirect is used internally by FireHOL helper commands. Only FireHOL developers should need to use this action directly. REJECT WITH MESSAGES The following RFCs contain information relevant to these messages: · RFC 1812 (http://www.ietf.org/rfc/rfc1812.txt) · RFC 1122 (http://www.ietf.org/rfc/rfc1122.txt) · RFC 792 (http://www.ietf.org/rfc/rfc0792.txt) icmp-net-unreachable; net-unreach ICMP network unreachable Generated by a router if a forwarding path (route) to the destination network is not available. From RFC 1812, section 188.8.131.52. See RFC 1812 and RFC 792. Note Use with care. The sender and the routers between you and the sender may conclude that the whole network your host resides in is unreachable, and prevent other traffic from reaching you. icmp-host-unreachable; host-unreach ICMP host unreachable Generated by a router if a forwarding path (route) to the destination host on a directly connected network is not available (does not respond to ARP). From RFC 1812, section 184.108.40.206. See RFC 1812 and RFC 792. Note Use with care. The sender and the routers between you and the sender may conclude that your host is entirely unreachable, and prevent other traffic from reaching you. icmp-proto-unreachable; proto-unreach ICMP protocol unreachable Generated if the transport protocol designated in a datagram is not supported in the transport layer of the final destination. From RFC 1812, section 220.127.116.11. See RFC 1812 and RFC 792. icmp-port-unreachable; port-unreach ICMP port unreachable Generated if the designated transport protocol (e.g. TCP, UDP, etc.) is unable to demultiplex the datagram in the transport layer of the final destination but has no protocol mechanism to inform the sender. From RFC 1812, section 18.104.22.168. See RFC 1812 and RFC 792. Generated by hosts to indicate that the required port is not active. icmp-net-prohibited; net-prohib ICMP communication with destination network administratively prohibited This code was intended for use by end-to-end encryption devices used by U.S. military agencies. Routers SHOULD use the newly defined Code 13 (Communication Administratively Prohibited) if they administratively filter packets. From RFC 1812, section 22.214.171.124. See RFC 1812 and RFC 1122. Note This message may not be widely understood. icmp-host-prohibited; host-prohib ICMP communication with destination host administratively prohibited This code was intended for use by end-to-end encryption devices used by U.S. military agencies. Routers SHOULD use the newly defined Code 13 (Communication Administratively Prohibited) if they administratively filter packets. From RFC 1812, section 126.96.36.199. See RFC 1812 and RFC 1122. Note This message may not be widely understood. tcp-reset TCP RST The port unreachable message of the TCP stack. See RFC 1122. Note tcp-reset is useful when you want to prevent timeouts on rejected TCP services where the client incorrectly ignores ICMP port unreachable messages. SEE ALSO · firehol(1) - FireHOL program · firehol.conf(5) - FireHOL configuration · firehol-interface(5) - interface definition · firehol-router(5) - router definition · firehol-params(5) - optional rule parameters · FireHOL Website (http://firehol.org/) · FireHOL Online PDF Manual (http://firehol.org/firehol-manual.pdf) · FireHOL Online HTML Manual (http://firehol.org/manual)FireHOL Reference Built 06 May 2015 firehol-actions(5)
|This manual||Reference||Other manuals|
|firehol-actions(5)||referred by||firehol-action(5) | firehol-client(5) | firehol-conf(5) | firehol-policy(5) | firehol-server(5) | firehol-variables(5)|
|refer to||firehol(1) | firehol-interface(5) | firehol-params(5) | firehol-router(5) | iptables(8)|