Copyright © 2001-2008 Thomas M. Eastep
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".
2008-11-20
Glossary
What is Shorewall?
Current Shorewall Releases
Getting Started with Shorewall
Looking for Information?
License
Important Notice to users of Shorewall Multi-ISP Feature -- UPDATED 7 November 2007
Important Notice to users of BRIDGING=Yes
Netfilter - the packet filter facility built into the 2.4 and later Linux kernels.
ipchains - the packet filter facility built into the 2.2 Linux kernels. Also the name of the utility program used to configure and control that facility. Netfilter can be used in ipchains compatibility mode.
iptables - the utility program used to configure and control Netfilter. The term 'iptables' is often used to refer to the combination of iptables+Netfilter (with Netfilter not in ipchains compatibility mode).
The Shoreline Firewall, more commonly
known
as "Shorewall", is a high-level tool for configuring Netfilter. You
describe
your firewall/gateway requirements using entries in a set of
configuration
files. Shorewall reads those configuration files and with the help of
the
iptables utility, Shorewall configures Netfilter to match your
requirements.
Shorewall can be used on a dedicated firewall system, a multi-function
gateway/router/server or on a standalone GNU/Linux system. Shorewall
does not
use Netfilter's ipchains compatibility mode; as a consequence,
Shorewall can
take advantage of Netfilter's connection state tracking capabilities to
create a stateful firewall.
Shorewall is not a daemon. Once Shorewall has configured
Netfilter,
it's job is complete and there is no Shorewall code left running in the
system. The /sbin/shorewall
program can be used at any time to monitor the Netfilter firewall.
Shorewall is not the easiest to use of the available iptables configuration tools but I believe that it is the most flexible and powerful. So if you are looking for a simple point-and-click set-and-forget Linux firewall solution that requires a minimum of networking knowledge, I would encourage you to check out the following alternatives:
On the other hand, if you are looking for a Linux firewall solution that can handle complex and fast changing network environments then Shorewall is a logical choice.
To see some of the many things that you
can
do with Shorewall, see the Shorewall
Features page.
The current
Stable Release version is 4.2.2
Read more about the Release here.
Get them from the download sites
New to Shorewall? Download the current Stable version (see above) then select the QuickStart Guide that most closely matches your environment and follow the step by step instructions.
The Documentation Index is a good place to start as is the Site Search in the frame above.
This program is free software; you can redistribute it and/or modify it under the terms of Version 2 of the GNU General Public License as published by the Free Software Foundation.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more detail.
You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, with no Front-Cover, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".
A bug in Shorewall versions 3.2.0-3.2.10, 3.4.0-3.4.6 and Shorewall-shell 4.0.0-4.0.2 prevents proper handling of PREROUTING marks when HIGH_ROUTE_MARKS=No and the track option is specified. Patches are available to correct this problem:
Shorewall version 3.2.0-3.2.10, 3.4.0-3.4.3: http://www1.shorewall.net/pub/shorewall/3.2/shorewall-3.2.10/errata/patches/Shorewall/patch-3.2.10-2.diff
Shorewall version 3.4.4-3.4.6: http://www1.shorewall.net/pub/shorewall/3.4/shorewall-3.4.66/errata/patches/Shorewall/patch-3.4.6-1.diff
Shorewall-shell version 4.0.0-4.0.2: http://www1.shorewall.net/pub/shorewall/4.0/shorewall-4.0.2/errata/patches/Shorewall-shell/patch-shell-4.0.2-2.diff
Note that a patch may succeed with an offset when applied to a release other than the one for which it was specifically prepared. For example, when the patch for 3.2.0-3.2.10, 3.4.0-3.4.3 (which was prepared for release 3.2.10) is applied to release 3.4.3, the following is the result:
root@wookie:~# cd /usr/share/shorewall root@wookie/usr/share/shorewall#: patch < ~/shorewall/tags/3.2.10/Shorewall.updated/patch-3.2.10-2.diff
patching file compiler
Hunk #1 succeeded at 958 (offset -1669 lines).
root@wookie:/usr/share/shorewall#
A second bug in Shorewall versions 3.2.0-3.2.11, 3.4.0-3.4.7 and 4.0.0-4.0.5 can cause improper handing of PREROUTING and OUTPUT marks when HIGH_ROUTE_MARKS=Yes. Patches are also available to correct this problem:
Shorewall version 3.2.3-3.2.11: http://www1.shorewall.net/pub/shorewall/3.2/shorewall-3.2.11/errata/patches/Shorewall/patch-3.2.11-1.diff
Shorewall version 3.4.0-3.4.7: http://www1.shorewall.net/pub/shorewall/3.4/shorewall-3.4.7/errata/patches/Shorewall/patch-3.4.7-1.diff
Shorewall version 4.0.0-4.0.5: http://www1.shorewall.net/pub/shorewall/4.0/shorewall-4.0.5/errata/patches/Shorewall-shell/patch-shell-4.0.5-1.diff and http://www1.shorewall.net/pub/shorewall/4.0/shorewall-4.0.5/errata/patches/Shorewall-perl/patch-perl-4.0.5-4.diff.
In Linux Kernel version 2.6.20, the Netfilter team changed Physdev Match so that it is no longer capable of supporting BRIDGING=Yes. The solutions available to users are to either:
The first approach allows you to switch back and forth between kernels older and newer than 2.6.20. The second approach is a better long-term solution.
LEAF is an open source project which provides a Firewall/router on a floppy, CD or CF. Several LEAF distributions including Bering and Bering-uClibc use Shorewall as their Netfilter configuration tool.
OpenWRT is a project which provides open source firmware for Linksys WRT54G wireless routers. Two different Shorewall packages are available for OpenWRT.
Shorewall
is free but if you try it and
find it useful, please consider making a donation to the Alzheimer's Association
or to
the Starlight
Children's
Foundation.
Thank You