FIREHOL(1) - Linux man page online | User commands

An easy to use but powerful iptables stateful firewall.

Built 04 Nov 2017
firehol(1) 3.1.5 firehol(1)


firehol - an easy to use but powerful iptables stateful firewall


firehol sudo -E firehol panic [ IP ] firehol command [ -- conf-arg... ] firehol CONFIGFILE [start|debug|try] [-- conf-arg... ]


Running firehol invokes iptables(8) to manipulate your firewall. Run without any arguments, firehol will present some help on usage. When given CONFIGFILE, firehol will use the named file instead of /etc/firehol/fire‐ hol.conf as its configuration. If no command is given, firehol assumes try. It is possible to pass arguments for use by the configuration file separating any conf-arg values from the rest of the arguments with --. The arguments are accessible in the con‐ figuration using standard bash(1) syntax e.g. $1, $2, etc. PANIC To block all communication, invoke firehol with the panic command. FireHOL removes all rules from the running firewall and then DROPs all traffic on all ipt‐ ables(8) tables (mangle, nat, filter) and pre-defined chains (PREROUTING, INPUT, FORWARD, OUTPUT, POSTROUTING). DROPing is not done by changing the default policy to DROP, but by adding one rule per ta‐ ble/chain to drop all traffic. This allows systems which do not reset all the chains to ACCEPT when starting to function correctly. When activating panic mode, FireHOL checks for the existence of the SSH_CLIENT shell envi‐ ronment variable, which is set by ssh(1). If it finds this, then panic mode will allow the established SSH connection specified in this variable to operate. Note In order for FireHOL to see the environment variable you must ensure that it is preserved. For sudo(8) use the -E and for su(1) omit the - (minus sign). If SSH_CLIENT is not set, the IP after the panic argument allows you to give an IP address for which all established connections between the IP address and the host in panic will be allowed to continue.


start; restart Activates the firewall using /etc/firehol/firehol.conf. Use of the term restart is allowed for compatibility with common init implementa‐ tions. try Activates the firewall, waiting for the user to type the word commit. If this word is not typed within 30 seconds, the previous firewall is restored. stop Stops a running iptables(8) firewall by clearing all of the tables and chains and setting the default policies to ACCEPT. This will allow all traffic to pass unchecked. condrestart Restarts the FireHOL firewall only if it is already active. This is the generally expected behaviour (but opposite to FireHOL prior to 2.0.0-pre4). status Shows the running firewall, using /sbin/iptables -nxvL | less. save Start the firewall and then save it using iptables-save(8) to the location given by FIREHOL_AUTOSAVE. See firehol-defaults.conf(5) for more information. The required kernel modules are saved to an executable shell script /var/spool/firehol/, which can be called during boot if a fire‐ wall is to be restored. Note External changes may cause a firewall restored after a reboot to not work as intended where starting the firewall with FireHOL will work. This is because as part of starting a firewall, FireHOL checks some change‐ able values. For instance the current kernel configuration is checked (for client port ranges), and RPC servers are queried (to allow correct function‐ ing of the NFS service). debug Parses the configuration file but instead of activating it, FireHOL shows the gen‐ erated iptables(8) statements. explain Enters an interactive mode where FireHOL accepts normal configuration commands and presents the generated iptables(8) commands for each of them, together with some reasoning for its purpose. Additionally, FireHOL automatically generates a configuration script based on the successful commands given. Some extra commands are available in explain mode. help Present some help show Present the generated configuration quit Exit interactive mode and quit helpme; wizard Tries to guess the FireHOL configuration needed for the current machine. FireHOL will not stop or alter the running firewall. The configuration file is given in the standard output of firehol, thus firehol helpme > /tmp/firehol.conf will produce the output in /tmp/firehol.conf. The generated FireHOL configuration must be edited before use on your systems. You are required to take a number of decisions; the comments in the generated file will instruct you in the choices you must make.




· firehol.conf(5) - FireHOL configuration · firehol-defaults.conf(5) - control variables · FireHOL Website ( · FireHOL Online PDF Manual ( · FireHOL Online Documentation (


FireHOL Team; Original man page by Marc Brockschmidt.
FireHOL Reference Built 04 Nov 2017 firehol(1)
This manual Reference Other manuals
firehol(1) referred by firehol-action(5) | firehol-actions(5) | firehol-blacklist(5) | firehol-client(5) | firehol-conf(5) | firehol-connmark(5) | firehol-cthelper(5) | firehol-defaults-conf(5) | firehol-dscp(5) | firehol-group(5) | firehol-interface(5) | firehol-ipset(5) | firehol-iptables(5) | firehol-iptrap(5) | firehol-mac(5) | firehol-mark(5) | firehol-masquerade(5) | firehol-modifiers(5) | firehol-nat(5) | firehol-params(5)
refer to bash(1) | firehol-conf(5) | firehol-defaults-conf(5) | iptables(8) | iptables-save(8) | ssh(1) | su(1) | sudo(8)
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