Shorewall 2.0

Tom Eastep

The information on this site applies only to 2.0.x releases of Shorewall. For older versions:

• The 1.4 site is here.

• The 1.3 site is here.

• The 1.2 site is here.

The current 2.0 Stable Release is 2.0.10 -- Here are the release notes.
The current Developement Release is 2.2.0 Beta 1 -- Here are the release notes.

Copyright © 2001-2004 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”.

2004-10-25

Table of Contents

Introduction to Shorewall

Glossary
What is Shorewall?
Getting Started with Shorewall
Looking for Information?
Running Shorewall on Mandrake® with a two-interface setup?
License

News

Shorewall 2.0.10
Shorewall 2.2.0 Beta 1

Donations

Introduction to Shorewall

Glossary

• 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).

What is Shorewall?

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 and can thus take advantage of Netfilter's connection state tracking capabilities.

Shorewall is not a daemon. Once Shorewall has configured Netfilter, it's job is complete. After that, there is no Shorewall code running although the /sbin/shorewall program can be used at any time to monitor the Netfilter firewall.

Getting Started with Shorewall

New to Shorewall? Start by selecting the QuickStart Guide that most closely matches your environment and follow the step by step instructions.

Looking for Information?

The Documentation Index is a good place to start as is the Quick Search in the frame above.

Running Shorewall on Mandrake® with a two-interface setup?

If so, the documentation on this site will not apply directly to your setup. If you want to use the documentation that you find here, you will want to consider uninstalling what you have and installing a setup that matches the documentation on this site. See the Two-interface QuickStart Guide for details.

Update: I've been informed by Mandrake Development that this problem has been corrected in Mandrake 10.0 Final (the problem still exists in the 10.0 Community release).

License

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., 675 Mass Ave, Cambridge, MA 02139, 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".

News

1. The GATEWAY column was previously ignored in 'pptpserver' entries in /etc/shorewall/tunnels.
2. When log rule numbers are included in the LOGFORMAT, duplicate rule numbers could previously be generated.
3. The /etc/shorewall/tcrules file now includes a note to the effect that rule evaluation continues after a match.
4. The error message produced if Shorewall couldn't obtain the routes through an interface named in the SUBNET column of /etc/shorewall/masq was less than helpful since it didn't include the interface name.
   

1. The "shorewall status" command has been enhanced to include the values of key /proc settings:
   
   Example from a two-interface firewall:
   
   /proc
   
      /proc/sys/net/ipv4/ip_forward = 1
      /proc/sys/net/ipv4/conf/all/proxy_arp = 0
      /proc/sys/net/ipv4/conf/all/arp_filter = 0
      /proc/sys/net/ipv4/conf/all/rp_filter = 0
      /proc/sys/net/ipv4/conf/default/proxy_arp = 0
      /proc/sys/net/ipv4/conf/default/arp_filter = 0
      /proc/sys/net/ipv4/conf/default/rp_filter = 0
      /proc/sys/net/ipv4/conf/eth0/proxy_arp = 0
      /proc/sys/net/ipv4/conf/eth0/arp_filter = 0
      /proc/sys/net/ipv4/conf/eth0/rp_filter = 0
      /proc/sys/net/ipv4/conf/eth1/proxy_arp = 0
      /proc/sys/net/ipv4/conf/eth1/arp_filter = 0
      /proc/sys/net/ipv4/conf/eth1/rp_filter = 0
      /proc/sys/net/ipv4/conf/lo/proxy_arp = 0
      /proc/sys/net/ipv4/conf/lo/arp_filter = 0
      /proc/sys/net/ipv4/conf/lo/rp_filter = 0
   

The features available in this release and the migration considerations are covered in the release notes. Highlights include:

1. The behavior produced by specifying a log level in an action invocation is now much more rational. Previously, all packets sent to the action were logged; now each rule within the invoked action behaves as if logging had been specified on it.
2. Support for the 2.6 Kernel's native IPSEC implementation is now available.
3. Support for ipp2p is included.
4. Support for the iptables CONNMARK facility is now included in Shorewall.
5. A new LOGALLNEW option facilitates problem analysis.
6. Users with a large static blacklist can now defer loading the blacklist until after the rest of the ruleset has been enabled. Doing so can decrease substantially the amount of time that connections are disabled during shorewall [re]start.
7. Support for the iptables 'iprange match' feature has been enabled. Users whose kernel and iptables contain this feature can use ip address ranges in most places in their Shorewall configuration where a CIDR netowrk can be used.
8. Accepting of source routing and martian logging may now be enabled/disabled on each interface.
9. Shorewall now supports the CLASSIFY iptable target.

More News

Leaf

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.

Donations

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.

Thanks