shorewall_code/Shorewall-perl/releasenotes.txt

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Shorewall-perl 3.9.1
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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.
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T H E G O O D N E W S:
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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.
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T H E B A D N E W S:
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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:]<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 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.
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P R E R E Q U I S I T E S
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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
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I N S T A L L A T I O N
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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
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U S I N G T H E N E W C O M P I L E R
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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.