related to the firewall discussion + security ...
dugan at passwall.com
Wed Feb 14 22:36:19 PST 2001
Thanks to Devin and Frank for a fun discussion. I bet most people
understood and were able to follow the presentation.
In the unlikely event there were a few people that did not follow it, you
might want to read further...
If you are very new to computers/networking had some problems with the
conceptual understanding of what a firewall policy and packet filter might
do, I put up a page on the net about 2 years ago (maybe 3 or 4) that gave
a simple review of packet filtering.
It is not Linux specific, and offers a symbolic example using my own
modification to the carrier pigeon analogy, which is often used for
describing TCP, to describe how an attack against packet fragmentation in
a stream (insertion) or general TCP attack might be overted with a
filter/firewall/router policy. (Yes, it is rather simple and is not a
perfect map for symbolism, bt is still somewhat entertaining.)
It should be an easy read, but I am a nerd, so YMMV:
I also have a main section that breaks down TCP, and UDP packets to
explain what kind of information is sent in their header. I also describe
many of the various ICMP types and codes as well as what they have been
used for and what RFC discusses them. The sections on TCP. UDP, and ICMP
are less verbose.
I have not touched the other topics on this for about a year or so, but it
might be helpful just the same:
Also a list of security related links for linux (mostly):
More information about the talk