---------------------------------------------------------------------------- Shorewall-perl 3.9.1 ---------------------------------------------------------------------------- This companion product to Shorewall 3.4.2 and later includes a complete rewrite of the compiler in Perl. Shorewall-perl depends on Shorewall (3.4.2 or later). So if you want to use the new compiler, you must install both Shorewall and Shorewall-perl. Even if you install Shorewall-perl, you have a choice of which compiler you use. The choice is specified in the shorewall.conf file so you can select the compiler to use on a system-by-system basis when running Shorewall Lite on remote systems. I decided to make Shorewall-perl a separate product for several reasons: a) Embedded applications are unlikely to adopt Shorewall-perl; even Mini-Perl has a substantial disk and Ram footprint. b) Because of the gross incompatibilities between the new compiler and the old (see below), migration to the new compiler must be voluntary. c) By allowing Shorewall-perl to co-exist with the current Shorewall stable release (3.4), I'm hoping that the new compiler will get more testing and validation than it would if I were to package it with a new development version of Shorewall itself. d) Along the same vein, I think that users will be more likely to experiment with the new compiler if they can easily fall back to the old one if things get sticky. ---------------------------------------------------------------------------- T H E G O O D N E W S: ---------------------------------------------------------------------------- a) The compiler has a small disk footprint. b) The compiler is very fast. c) The compiler generates a firewall script that uses iptables-restore; so the script is very fast. d) Use of the perl compiler is optional! The old slow clunky Bourne-shell compiler is still available. ---------------------------------------------------------------------------- T H E B A D N E W S: ---------------------------------------------------------------------------- There are a number of incompatibilities between the Perl-based compiler and the Bourne-shell one. Some of these will probably go away by first official release but most will not. a) The Perl-based compiler requires the following capabilities in your kernel and iptables. - addrtype match (may be relaxed later) - multiport match (will not be relaxed) These capabilities are in current distributions. b) Now that Netfilter has features to deal reasonably with port lists, I see no reason to duplicate those features in Shorewall. The Bourne-shell compiler goes to great pain (in some cases) to break very long port lists ( > 15 where port ranges in lists count as two ports) into individual rules. In the new compiler, I'm avoiding the ugliness required to do that. The new compiler just generates an error if your list is too long. It will also produce an error if you insert a port range into a port list and you don't have extended multiport support. c) BRIDGING=Yes is not supported. The kernel code necessary to support this option was removed in Linux kernel 2.6.20. d) The BROADCAST column in the interfaces file is essentially unused; if you enter anything in this column but '-' or 'detect', you will receive a warning. This will be relaxed if and when the addrtype match requirement is relaxed. e) Because the compiler is now written in Perl, your compile-time extension scripts from earlier versions will no longer work. For now, if you want to use extension scripts, you will need to read the Perl code to see how the compiler operates internally. I will produce documentation before the first official release. Compile-time extension scripts are executed using the Perl 'do FILE' mechanism. f) The 'refresh' command is now synonymous with 'restart'. g) Some run-time extension scripts are no longer supported because they make no sense (iptables-restore instantiates the new configuration atomically). continue initdone continue refresh refreshed h) The /etc/shorewall/tos file now has zone-independent SOURCE and DEST columns as do all other files except the rules and policy files. The SOURCE column may be one of the following: [all:]
[,...] [all:][:
[,...]] $FW[:
[,...]] The DEST column may be one of the following: [all:]
[,...] [all:][:
[,...]] This is a permanent change. The old zone-based rules have never worked right and this is a good time to replace them. I've tried to make the new syntax cover the most common cases without requiring change to existing files. In particular, it will handle the tos file released with Shorewall 1.4 and earlier. i) Currently, support for ipsets is untested. That will change with future pre-releases but one thing is certain -- Shorewall is now out of the ipset load/reload business. With scripts generated by the Perl-based Compiler, the Netfilter ruleset is never cleared. That means that there is no opportunity for Shorewall to load/reload your ipsets since that cannot be done while there are any current rules using ipsets. So: i) Your ipsets must be loaded before Shorewall starts. You are free to try to do that with the following code in /etc/shorewall/start: if [ "$COMMAND" = start ]; then ipset -U :all: :all: ipset -F ipset -X ipset -R < /my/ipset/contents fi The file '/my/ipset/contents' (not its real name of course) will normally be produced using the ipset -S command. The above will work most of the time but will fail in a 'shorewall stop' - 'shorewall start' sequence if you use ipsets in your routestopped file (see below). ii) Your ipsets may not be reloaded until Shorewall is stopped or cleared. iii) If you specify ipsets in your routestopped file then Shorewall must be cleared in order to reload your ipsets. As a consequence, scripts generated by the Perl-based compiler will ignore /etc/shorewall/ipsets and will issue a warning if you set SAVE_IPSETS=Yes in shorewall.conf. j) Because the configuration files (with the exception of /etc/shorewall/params) are now processed by the Perl-based compiler rather than by the shell, only the basic forms of Shell expansion ($variable and ${variable}) are supported. The more exotic forms such as ${variable:=default} are not supported. Both variables defined in /etc/shorewall/params and environmental variables (exported by the shell) can be used in configuration files. h) USE_ACTIONS=No is not supported. That option is intended to minimize Shorewall's footprint in embedded applications. As a consequence, Default Macros are not supported. i) DELAYBLACKLISTLOAD=Yes is not supported. The entire ruleset is atomically loaded with one execution of iptables-restore. j) MAPOLDACTIONS=Yes is not supported. People should have converted to using macros by now. k) The pre Shorewall-3.0 format of the zones file is not supported; neither is the /etc/shorewall/ipsec file. ---------------------------------------------------------------------------- P R E R E Q U I S I T E S ---------------------------------------------------------------------------- In addition to Shorewall-3.4.2 or later, you need: - Perl (I use Perl 5.8.8 but other versions should work fine) - Perl Cwd Module - Perl File::Basename Module - Perl File::Temp Module ---------------------------------------------------------------------------- I N S T A L L A T I O N ---------------------------------------------------------------------------- Either $ tar -jxf shorewall-perl-3.9.1.tar.bz2 $ cd shorewall-perl-3.9.1 $ ./install.sh or $ rpm -ivh shoreawll-pl-3.9.1-1.noarch.rpm ---------------------------------------------------------------------------- U S I N G T H E N E W C O M P I L E R ---------------------------------------------------------------------------- By default, the old Bourne-shell based compiler will be used. To use the new compiler, add this to shorewall.conf: SHOREWALL_COMPILER=perl If you add this setting to /etc/shorewall/shorewall.conf then by default, the new compiler will be used on the system. If you add it to shorewall.conf in a separate directory (such as a Shorewall-lite export directory) then the new compiler will only be used when you compile from that directory. Regardless of the setting of SHOREWALL_COMPILER, there is one change in Shorewall operation that is triggered simply by installing shorewall-perl. Your params file will be processed with the shell's '-a' option which causes any variables that you set or create in that file to be automatically exported. Since the params file is processed before shorewall.conf, using -a insures that the settings of your params variables are available to the new compiler should it's use be specified in shorewall.conf.