shorewall_code/New/releasenotes.txt

Shorewall-perl 3.9.0

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.

The good news:

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.

The bad news:

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 some 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:]<address>[,...]
       [all:]<interface>[:<address>[,...]]
       $FW[:<address>[,...]]

   The DEST column may be one of the following:
       [all:]<address>[,...]
       [all:]<interface>[:<address>[,...]]

   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.

h) Line continuation (lines ending in '\' are concatinated with the next
   line) continues to be supported. Unlike the shell-based compiler,
   however, the Perl-based compiler does not continue lines that end
   in '#' comments. This avoids the confusing behavior where
   the last line of a comment ends with '\', causing the
   next (non-comment) line to be ignored.

   Example (/etc/shorewall/tunnels):

   # VPN from Atlanta \
   openvpn-server     net	206.124.146.177    
   
   With the Shell-based compiler, the openvpn-server line is ignored
   because it is combined with the preceding line; with the Perl-based
   compiler, it is processed normally.


Installation
------------

Either 

   $ tar -jxf shorewall-perl-3.9.0.tar.bz2
   $ cd shorewall-perl-3.9.0
   $ ./install.sh

or

   $ rpm -ivh shoreawll-pl-3.9.0-1.noarch.rpm

Using the New compiler
----------------------

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.