Copyright © 2007, 2009 Thomas M. Eastep
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Table of Contents
Shorewall version 4.0 represented a substantial shift in direction for Shorewall. Up until then
Shorewall had been written entirely in Bourne Shell.
Shorewall had run the iptables utility to add each Netfilter rule.
Shorewall version 4.0 offered you a choice. You could continue to use the existing shell-based implementation or you could use a new implementation of the Shorewall compiler written in the Perl programming language. The new compiler:
had a small disk footprint
was very fast.
generateed a firewall script that uses iptables-restore; so the script was very fast.
generated better and more consistent error messages.
did a much more thorough job of checking the configuration to avoid run-time errors.
supported creating either Ipv4 or Ipv6 firewalls (Shorewall 4.2.4 and later).
Shorewall 4.4 (currently in Beta testing) discontinues the availability of the legacy shell-based compiler. All users must migrate to the perl-based compiler before or during an upgrade to Shorewall version 4.4. We highly recommend that current users of the shell-based compiler migrate before upgrading to 4.4 so that both compilers are available during the migration.
Shorewall 4.4 contains four packages:
Shorewall - Everything needed to create an IPv4 firewall.
Shorewall-lite- Can run scripts generated by Shorewall on another system.
Shorewall6 - The utilities for creating and operating an Ipv6 firewall. Requires Shorewall.
Shorewall6-lite - Ipv6 equivalent of Shorewall Lite. Can run scripts generated by Shoreall on another system.
Perl (I use Perl 5.8.10 but other 5.8 versions should work fine).
If you want to be able to use DNS names in your Shorewall6 configuration files, then Perl 5.10 is required together with the Perl Socket6 module.
Perl Cwd Module
Perl File::Basename Module
Perl File::Temp Module
Perl Getopt::Long Module
Perl Carp Module
Perl FindBin Module
Perl Scalar::Util Module
Please note that there are additional requirements if you plan to install and use Shorewall6.
The Shorewall Perl-based compiler is not 100% compatible with the Shorewall shell-based version. See this document for details.