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133 lines
4.3 KiB
Plaintext
133 lines
4.3 KiB
Plaintext
Shorewall-pl 3.9.0
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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-pl 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-pl.
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Even if you install Shorewall-pl, 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-pl a separate product for several reasons:
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a) Embedded applications are unlikely to adopt Shorewall-pl; 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-pl 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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The good news:
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a) The compiler is small.
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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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The bad news:
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There are a number of incompatibilities between the Perl-based compiler
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and the Bourne-shell one.
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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
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- conntrack match
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- extended multiport match
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These capabilities are in current distributions.
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b) 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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c) The BROADCAST column in the interfaces file is essentailly unused;
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if you enter anything in this column but '-' or 'detect', you will
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receive a warning.
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d) Because the compiler is now written in Perl, your compile-time
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extension scripts from earlier versions will no longer work.
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e) The 'refresh' command is now synonamous with 'restart'.
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f) 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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g) Currently, support for ipsets is untested. That will change with
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future releases but one thing is certain -- Shorewall is now out of the
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ipset load/reload business. If the Netfilter ruleset is never cleared,
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then there is no opportunity for Shorewall to load/reload your
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ipsets.
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So:
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i) Your ipsets must be loaded before Shorewall starts.
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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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Installation
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------------
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1) Unpack the tarball.
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$ tar -jxf shorewall-pl-3.9.0-1.tar.bz2
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$ pwd
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/home/teastep/shorewall/
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$ ls
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shorewall-pl-3.9.0/
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$
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2) As root, create a symbolic link to the directory containing the unpacked
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files.
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$ ln -sf /home/teastep/shorewall/ /usr/share/shorewall-pl
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Using the New compiler
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----------------------
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By default, the old Bourne-shell based compiler will be used.
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There is one change in Shorewall operation that is triggered when
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/usr/share/shorewall-pl exists and is either a directory or a symbolic
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link that points to a directory: Your params file will be processed
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with the shell's '-a' option set which will automatically export any
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variables that you set or create.
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To actually use the new compiler, add this to shorewall.conf:
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SHOREWALL_PL=Yes
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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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