Anatomy of Shorewall 4.0 Tom Eastep 2007 Thomas M. Eastep Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts. A copy of the license is included in the section entitled GNU Free Documentation License.
Products Shorewall 4.0 consists of four packages. Shorewall-common. This package must be installed on at least one system in your network. That system must also have Shorewall-shell and/or Shorewall-perl installed. Shorewall-shell. This package includes the legacy Shorewall configuration compiler written in Bourne Shell. This compiler is very portable but suffers from performance problems and has become hard to maintain. Shorewall-perl. An alternative to Shorewall-shell written in the Perl language. This compiler is highly portable to those Unix-like platforms that support Perl (including Cygwin) and is the compiler of choice for new Shorewall installations. Shorewall-lite. Shorewall allows for central administration of multiple firewalls through use of Shorewall lite. The full Shorewall product (along with Shorewall-shell and/or Shorewall-perl) are installed on a central administrative system where compiled Shorewall scripts are generated. These scripts are copied to the firewall systems where they run under the control of Shorewall-lite.
Shorewall-common The Shorewall-common package includes a large number of files which are installed in /sbin, /usr/share/shorewall, /etc/shorewall, /etc/init.d and /var/lilb/shorewall/. These are described in the sub-sections that follow.
/sbin The /sbin/shorewall shell program is use to interact with Shorewall. See shorewall(8).
/usr/share/shorewall The bulk of Shorewall is installed here. action.template - template file for creating actions. action.* - standard Shorewall actions. actions.std - file listing the standard actions. configfiles - A directory containing configuration files to copy to create a Shorewall-lite export directory. configpath - A file containing distribution-specific path assignments. firewall - A shell program that handles the add and delete commands (see shorewall(8)). It also handles the stop and clear commands when there is no current compiled firewall script on the system. functions - A symbolic link to lib.base that provides for compatibility with older versions of Shorewall. init - A symbolic link to the init script (usually /etc/init.d/shorewall). lib.* - Shell function libraries used by the other shell programs. macro.* - The standard Shorewall macros. modules - File that drives the loading of Netfilter kernel modules. May be overridden by /etc/shorewall/modules. version - A file containing the currently install version of Shorewall. wait4ifup - A shell program that extension scripts can use to delay until a network interface is available.
/etc/shorewall This is where the modifiable configuration files are installed.
/etc/init.d or /etc/rc.d (depends on distribution) An init script is installed here. Depending on the distribution, it is named shorewall or rc.firewall.
/var/lib/shorewall Shorewall doesn't install any files in this directory but rather uses the directory for storing state information. This directory may be relocated using shorewall-vardir(5). chains - If DYNAMIC_ZONES=Yes in shorewall.conf(5), this file contains information used by the add and delete commands (see shorewall(8)). .iptables-restore-input - The file passed as input to the iptables-restore program to initialize the firewall during the last start or restart command (see shorewall(8)). .modules - The contents of the modules file used during the last start or restart command (see shorewall(8) for command information). .modulesdir - The MODULESDIR setting (shorewall.conf(5)) at the last start or restart. nat - This unfortunately-named file records the IP addresses added by ADD_SNAT_ALIASES=Yes and ADD_IP_ALIASES=Yes in shorewall.conf(5). proxyarp - Records the arp entries added by entries in shorewall-proxyarp(5). .refresh - The shell program that performed the last successful refresh command. .restart - The shell program that performed the last successful restart command. restore - The default shell program used to execute restore commands. .restore - The shell program that performed the last successful refresh, restart or start command. save - File created by the save command and used to restore the dynamic blacklist during start/restart. .start - The shell program that performed the last successful start command. state - Records the current firewall state. zones - Records the current zone contents.
Shorewall-shell The Shorewall-shell product installs all of its files in /usr/share/shorewall-shell. compiler - The configuration compiler shell program. lib.* - Shell function libraries used by the compiler. On embedded systems, only a sub-set of the available libraries may be installed as a space-saving measure. prog.* - Shell program fragments used as input to the compiler. version - A file containing the currently install version of Shorewall-shell.
Shorewall-perl The Shorewall-perl product installs all of its files in /usr/share/shorewall-perl. buildports.pl - A Perl program that builds the Shorewall/Ports.pm module during installation. compiler.pl - The configuration compiler perl program. prog.* - Shell program fragments used as input to the compiler. Shorewall - Directory containing the Shorewall Perl modules used by the compiler. version - A file containing the currently install version of Shorewall-shell.
Shorewall-lite The Shorewall-lite product includes files installed in /sbin, /usr/share/shorewall-lite, /etc/shorewall-lite, /etc/init.d and /var/lilb/shorewall/. These are described in the sub-sections that follow.
/sbin The /sbin/shorewall-lite shell program is use to interact with Shorewall lite. See shorewall-lite(8).
/etc/init.d or /etc/rc.d (depends on distribution) An init script is installed here. Depending on the distribution, it is named shorewall-lite or rc.firewall.
/etc/shorewall-lite This is where the modifiable configuration files are installed.
/usr/share/shorewall-lite The bulk of Shorewall-lite is installed here. configpath - A file containing distribution-specific path assignments. functions - A symbolic link to lib.base that provides for compatibility with older versions of Shorewall. lib.* - Shell function libraries used by the other shell programs. These are copies of the corresponding libraries in the Shorewall product. modules - File that drives the loading of Netfilter kernel modules. May be overridden by /etc/shorewall-lite/modules. shorecap - A shell program used for generating capabilities files. See the Shorewall-lite documentation. version - A file containing the currently install version of Shorewall. wait4ifup - A shell program that extension scripts can use to delay until a network interface is available.
/var/lib/shorewall-lite Shorewall-lite doesn't install any files in this directory but rather uses the directory for storing state information. This directory may be relocated using shorewall-lite-vardir(5). firewall - Compiled shell script installed by running the load or reload command on the administrative system (see shorewall(8)). firewall.conf - Digest of the shorewall.conf file used to compile the firewall script on the administrative system. .iptables-restore-input - The file passed as input to the iptables-restore program to initialize the firewall during the last start or restart command (see shorewall-lite(8)). .modules - The contents of the modules file used during the last start or restart command (see shorewall-lite(8) for command information). .modulesdir - The MODULESDIR setting (shorewall.conf(5)) at the last start or restart. nat - This unfortunately-named file records the IP addresses added by ADD_SNAT_ALIASES=Yes and ADD_IP_ALIASES=Yes in shorewall.conf(5). proxyarp - Records the arp entries added by entries in shorewall-proxyarp(5). .refresh - The shell program that performed the last successful refresh command. .restart - The shell program that performed the last successful restart command. restore - The default shell program used to execute restore commands. .restore - The shell program that performed the last successful refresh, restart or start command. save - File created by the save command and used to restore the dynamic blacklist during start/restart. .start - The shell program that performed the last successful start command. state - Records the current firewall state. zones - Records the current zone contents.