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git-svn-id: https://shorewall.svn.sourceforge.net/svnroot/shorewall/trunk@5814 fbd18981-670d-0410-9b5c-8dc0c1a9a2bb
215 lines
9.0 KiB
Plaintext
215 lines
9.0 KiB
Plaintext
----------------------------------------------------------------------------
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Shorewall-perl 3.9.1
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----------------------------------------------------------------------------
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This companion product to Shorewall 3.4.2 and later includes a complete
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rewrite of the compiler in Perl.
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Shorewall-perl depends on Shorewall (3.4.2 or later). So if you want to use the
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new compiler, you must install both Shorewall and Shorewall-perl.
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Even if you install Shorewall-perl, you have a choice of which compiler you use.
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The choice is specified in the shorewall.conf file so you can select the
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compiler to use on a system-by-system basis when running Shorewall Lite on
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remote systems.
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I decided to make Shorewall-perl a separate product for several reasons:
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a) Embedded applications are unlikely to adopt Shorewall-perl; even Mini-Perl
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has a substantial disk and Ram footprint.
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b) Because of the gross incompatibilities between the new compiler and the
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old (see below), migration to the new compiler must be voluntary.
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c) By allowing Shorewall-perl to co-exist with the current Shorewall stable
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release (3.4), I'm hoping that the new compiler will get more testing and
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validation than it would if I were to package it with a new development
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version of Shorewall itself.
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d) Along the same vein, I think that users will be more likely to experiment
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with the new compiler if they can easily fall back to the old one if things
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get sticky.
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----------------------------------------------------------------------------
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T H E G O O D N E W S:
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----------------------------------------------------------------------------
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a) The compiler has a small disk footprint.
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b) The compiler is very fast.
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c) The compiler generates a firewall script that uses iptables-restore;
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so the script is very fast.
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d) Use of the perl compiler is optional! The old slow clunky
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Bourne-shell compiler is still available.
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----------------------------------------------------------------------------
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T H E B A D N E W S:
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----------------------------------------------------------------------------
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There are a number of incompatibilities between the Perl-based compiler
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and the Bourne-shell one. Some of these will probably go away by first
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official release but most will not.
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a) The Perl-based compiler requires the following capabilities in your
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kernel and iptables.
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- addrtype match (may be relaxed later)
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- multiport match (will not be relaxed)
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These capabilities are in current distributions.
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b) Now that Netfilter has features to deal reasonably with port lists,
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I see no reason to duplicate those features in Shorewall. The
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Bourne-shell compiler goes to great pain (in some cases) to
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break very long port lists ( > 15 where port ranges in lists count
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as two ports) into individual rules. In the new compiler, I'm
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avoiding the ugliness required to do that. The new compiler just
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generates an error if your list is too long. It will also produce
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an error if you insert a port range into a port list and you don't
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have extended multiport support.
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c) BRIDGING=Yes is not supported. The kernel code necessary to
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support this option was removed in Linux kernel 2.6.20.
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d) The BROADCAST column in the interfaces file is essentially unused;
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if you enter anything in this column but '-' or 'detect', you will
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receive a warning. This will be relaxed if and when the addrtype
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match requirement is relaxed.
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e) Because the compiler is now written in Perl, your compile-time
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extension scripts from earlier versions will no longer work. For
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now, if you want to use extension scripts, you will need to read the
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Perl code to see how the compiler operates internally. I will
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produce documentation before the first official release.
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Compile-time extension scripts are executed using the Perl
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'do FILE' mechanism.
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f) The 'refresh' command is now synonymous with 'restart'.
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g) Some run-time extension scripts are no longer supported because they
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make no sense (iptables-restore instantiates the new configuration
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atomically).
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continue
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initdone
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continue
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refresh
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refreshed
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h) The /etc/shorewall/tos file now has zone-independent SOURCE and DEST
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columns as do all other files except the rules and policy files.
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The SOURCE column may be one of the following:
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[all:]<address>[,...]
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[all:]<interface>[:<address>[,...]]
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$FW[:<address>[,...]]
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The DEST column may be one of the following:
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[all:]<address>[,...]
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[all:]<interface>[:<address>[,...]]
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This is a permanent change. The old zone-based rules have never
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worked right and this is a good time to replace them. I've tried to
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make the new syntax cover the most common cases without requiring
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change to existing files. In particular, it will handle the tos file
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released with Shorewall 1.4 and earlier.
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i) Currently, support for ipsets is untested. That will change with
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future pre-releases but one thing is certain -- Shorewall is now out
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of the ipset load/reload business. With scripts generated by the
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Perl-based Compiler, the Netfilter ruleset is never cleared. That
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means that there is no opportunity for Shorewall to load/reload your
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ipsets since that cannot be done while there are any current rules
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using ipsets.
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So:
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i) Your ipsets must be loaded before Shorewall starts. You
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are free to try to do that with the following code in
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/etc/shorewall/start:
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if [ "$COMMAND" = start ]; then
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ipset -U :all: :all:
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ipset -F
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ipset -X
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ipset -R < /my/ipset/contents
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fi
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The file '/my/ipset/contents' (not its real name of
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course) will normally be produced using the ipset -S
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command.
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The above will work most of the time but will fail in a
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'shorewall stop' - 'shorewall start' sequence if you
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use ipsets in your routestopped file (see below).
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ii) Your ipsets may not be reloaded until Shorewall is stopped or
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cleared.
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iii) If you specify ipsets in your routestopped file then
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Shorewall must be cleared in order to reload your ipsets.
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As a consequence, scripts generated by the Perl-based compiler will
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ignore /etc/shorewall/ipsets and will issue a warning if you set
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SAVE_IPSETS=Yes in shorewall.conf.
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j) Because the configuration files (with the exception of
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/etc/shorewall/params) are now processed by the Perl-based compiler
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rather than by the shell, only the basic forms of Shell expansion
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($variable and ${variable}) are supported. The more exotic forms
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such as ${variable:=default} are not supported. Both variables
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defined in /etc/shorewall/params and environmental variables
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(exported by the shell) can be used in configuration files.
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h) USE_ACTIONS=No is not supported. That option is intended to minimize
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Shorewall's footprint in embedded applications. As a consequence,
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Default Macros are not supported.
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i) DELAYBLACKLISTLOAD=Yes is not supported. The entire ruleset is
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atomically loaded with one execution of iptables-restore.
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j) MAPOLDACTIONS=Yes is not supported. People should have converted to
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using macros by now.
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k) The pre Shorewall-3.0 format of the zones file is not supported;
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neither is the /etc/shorewall/ipsec file.
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----------------------------------------------------------------------------
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P R E R E Q U I S I T E S
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----------------------------------------------------------------------------
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In addition to Shorewall-3.4.2 or later, you need:
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- Perl (I use Perl 5.8.8 but other versions should work fine)
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- Perl Cwd Module
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- Perl File::Basename Module
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- Perl File::Temp Module
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----------------------------------------------------------------------------
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I N S T A L L A T I O N
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----------------------------------------------------------------------------
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Either
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$ tar -jxf shorewall-perl-3.9.1.tar.bz2
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$ cd shorewall-perl-3.9.1
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$ ./install.sh
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or
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$ rpm -ivh shoreawll-pl-3.9.1-1.noarch.rpm
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----------------------------------------------------------------------------
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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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----------------------------------------------------------------------------
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By default, the old Bourne-shell based compiler will be used.
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To use the new compiler, add this to shorewall.conf:
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SHOREWALL_COMPILER=perl
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If you add this setting to /etc/shorewall/shorewall.conf then by
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default, the new compiler will be used on the system. If you add it to
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shorewall.conf in a separate directory (such as a Shorewall-lite export
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directory) then the new compiler will only be used when you compile
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from that directory.
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Regardless of the setting of SHOREWALL_COMPILER, there is one change in
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Shorewall operation that is triggered simply by installing
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shorewall-perl. Your params file will be processed with the shell's
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'-a' option which causes any variables that you set or create in that
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file to be automatically exported. Since the params file is processed
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before shorewall.conf, using -a insures that the settings of your
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params variables are available to the new compiler should it's use be
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specified in shorewall.conf.
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