Re: tcp/ip filtering

Coolio (omnilord@igc.net)
Fri, 17 May 1996 09:37:48 -0400 (EDT)


On Thu, 16 May 1996, Albert Cahalan wrote:

> From: Coolio <omnilord@igc.net>
> > On the subject of implementing a server based tcp/ip packet filtering
> > system...

> AOL got into trouble when women discovered they could not discuss
> breast cancer anymore. Prodigy had trouble with vietnamese users,
> because they often write "sex" as part of an ASCII transliteration.

Luckily there wont be any students afflicted with breast cancer or lots
of vietnamese users at my high school... Mainly I hope to duplicate the
abilities of Surf Watch..

> User complaint: "I can't FTP the Linux kernel!"

hehe... well, if there happen to be some words (separated by non
characters) that are on the ban list, and they pass through the filter,
they will be blocked... I have seen some binaries with actual words in
them occasionally, but very rarely... and on the slim chance the word is
also on the ban list, then it would be a freak coincidence and the ban
could possibly be lifted to download the file...

> N f s Y w n a 1 A p a l
> o u h o i e 5 I a t e
> c i u l e M r a
> k t l d B s s
> i . e t
> n r .

Exactly, its easy to fool the censor, but for the most part the
information that is being retrieved will be in normal format, and will be
caught by the censor... I have not heard of people actively writing their
web pages like that just to get past filters, however it might become
more prevalent in the future... Until then, a simple filter would be enough..

> Think you can block this?

:) no but like I said, a simple little filter like what SurfWatch has
would be enough to block most things and satisfy nervous teachers to a
certain degree..