# Shorewall Requirements

### Tom Eastep

Copyright © 2001-2006 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”.

2006-06-07

### Caution

This article applies to Shorewall 3.0 and later. If you are running a version of Shorewall earlier than Shorewall 3.0.0 then please see the documentation for that release.

## Shorewall Requires:

- A Linux kernel that supports netfilter (No, it won't work on BSD or Solaris). I've tested with 2.4.2 - 2.6.16. Check here for kernel configuration information.

- iptables 1.2 or later (but I recommend at least version 1.3.3)

- Iproute (“ip” and "tc" utilities). The iproute package is included with most distributions but may not be installed by default. The official download site is http://developer.osdl.org/dev/iproute2/download/.

- A Bourne shell or derivative such as bash or ash. This shell must have correct support for variable expansion formats ${variable%pattern}, ${variable%%pattern}, ${variable#pattern} and ${variable##pattern}.

- Your shell must produce a sensible result when a number n (128 <= n <= 255) is left shifted by 24 bits. You can check this at a shell prompt by:

  - echo $((128 << 24))

  - The result must be either 2147483648 or -2147483648.

- The firewall monitoring display is greatly improved if you have awk (gawk) installed.