If you're looking for the HTML::Mason Perl Module, try here.
"If you have not checked out Mason, I highly recommend it. Mason is a Linux based firewall, but none like you've ever used.
In short, you put Mason into learning mode and run the services to the Internet you wish to support. Mason will then take these log entries and turn them into a set of packet filtering rules. Pretty cool eh? No ACK compliment rules to worry about, no "what was that service port again?" decisions to worry about, simply plug it in, let it learn and off you go. :)"
- - Chris Brenton, cbrenton@sover.net
Mason is a tool that interactively builds a firewall using Linux' ipfwadm or ipchains firewalling. You leave mason running on the firewall machine while you are making all the kinds of connections that you want the firewall to support (and want it to block). Mason gives you a list of firewall rules that exactly allow and block those connections.
Mason was specifically designed to make it possible for anyone with the ability to generally find their way around a Linux system to build a reasonably good packet filtering firewall for any and every system under their control. It takes care of all the low level grunt work; all you need to do is follow the instructions and be able to run all the TCP/IP applications that need to be supported.
The real work of the package is done by the mason script. Its job is to convert the log entries that the Linux kernel produces into ipfwadm or ipchains commands that you can use in your own firewall.
In order to make it easy to use, I have included a rudimentary tool called mason-gui-text. It's a very simple shell that handles the setup and creation process for those that want to be led through the process. It would sincerely like to see it replaced with a nicer interface.
My hat is off to Rusty, who has done it again. I've gotten netfilter running on 2.3.x and I'm really impressed. When I insert the ipfwadm module, Mason runs just fine. When I insert ipchains.o, hey, Mason runs just fine. I haven't tried all the features, but this is going to make debugging Mason much easier. And hey, it looks like its going to be in 2.4.x!
In preparation for 0.13.1, the documentation has gotten a lot of work. I've merged a bunch of stuff into a main SGML file which can be viewed in .txt or .html format. I'm glad to say the documentation is finally usable again.
I've included a copy of the disclaimers. Like all GNU programs:
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 details.
Unfortunately, because this program is so deeply involved in the security of the systems on which it is run, I need to add this disclaimer as well:
This program offers an aid to creating firewall rules. It offers
ABSOLUTELY NO intelligence in deciding what should be allowed or
disallowed. It has ABSOLUTELY NO ability to understand your security
policy and implement it. YOU are responsible for reviewing the rules and
massaging them to fit your needs.
While the documentation in mason.txt attempts to provide some
general guidelines on how to use Mason, please remember: the author has
no knowledge of what you want your firewall to do and has not tailored the
documentation or program to specially fit your needs. If there is ever a
discrepancy between your needs and the program output or your needs and
the documentation, the program and/or documentation are _dead_ _wrong_.
Here are the various versions available for download, most recent at the top.
Mason-0.13.0.92 developers release (tar, noarch rpm, src rpm).
If you've had trouble with Mason crashing, please give this release a try. I think I've finally found the right way to tell Mason to exit, and I'm catching the rest of the otherwise harmless return codes. 0.13.0.92 is good enough that I'd suggest it over any previous version.
I've started a regression test suite for Mason. While not terribly useful to most users, it does help with quality control; it's harder for me to introduce errors.
Mason now gives a single warning if it sees non-tcp/udp/icmp protocols when working with ipfwadm.
Mason-0.13.0.90 developers release (tar, noarch rpm, src rpm).
New to this release: A large number of backdoor ports that can be automatically blocked in masonrc, bug fixes for dynamic address support, complete restructuring of the documentation (now in .sgml, viewable in .txt and .html), minor fixes, bugfix for NOOUTGOING icmp subcode support, NOOUTGOING tcp protocols automatically test for the SYN flag, first fragments of iptables support (as of 9/26/99, this is not functional).
Mason-0.13.0 final release (tar, noarch rpm, src rpm).
New to this release: automatically makes masq rules for reserved addresses, icmp subcodes, support for ip tunneling and a number of other protocols, removal of the namecache (no longer needed), mason now stops logging packets quickly while it does the main processing, stop using ipcalc to calculate broadcast, don't touch /etc/hosts or /etc/services, more Debian integration and two man pages (Thanks, Jeff!), support for ipchains-save output format, support for --sport and --dport (Thanks, Rusty!), some documentation updates, the ability to add packet counts to each rule, sorting the most commonly used rules to the top, misc. bug fixes and performance improvements, fixes to the Cisco output format, the ability to generalize the ack rules for tcp connections, cutting 25%-35% of the rules (Use at your own risk for the moment - this needs to be checked), an internal checkpointing ability to help in debugging, Mason can find the smallest subnet that encompasses the ips found on a dynamic interface and no_outgoing_ protocols.
Support for ipchains -Lnxv input format was planned, but scrapped when I realized there was an easier way to get packet counts into Mason.
Known bug: Mason occasionally exits during the course of normal operation. It complains on the way out that it has "crashed", when the exit was intentional. I'm still working with the trap logic to stop it from complaining when it shouldn't.
The Mason package now includes some additional "services" files. If you choose, Mason can automatically pull services from these files if your /etc/services file is missing them. Many thanks to the guys who wrote nmap for the nmap-services file.
Ironically, I do not suggest you use these as they are too complete; Mason may actually have trouble generalizing its rules because everything looks like a server port.
I also added TOS (Type Of Service) flag setting to this version. That, in theory, should help interactive performance on slow links with lots of bulk traffic. I also added the ability to completely block individual IP's or entire subnets.
Here's how to install:
Here are the individual files you can download. These files may be newer than the ones in the packages above; if so, they are here as prerelease version for those who want to be on the bleeding edge.
An important note - rules in newrules are not part of your regular firewall - they are only used during the learning process. This is why you need to merge rules from newrules to baserules once you're sure of them.
Most of the files in the Mason package are Copyright (c) 1998, 1999 by William Stearns wstearns@pobox.com or Jeff Licquia. They are released under the GNU GPL, which is included in the package. If you did not recieve a copy of this license, please contact the author for a copy (see the top of the Mason script for contact information for the author and the Free Software Foundation).
Last edited: 9/26/99
Best viewed with something that can show web pages... <grin>