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From: "Dennis V. Kreminsky" <Dennis.Kreminsky@itcnet.ru>
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: Re: ipfw use as a traffic analyzer
Date: Tue, 15 Jul 1997 06:51:35 +0000
Organization: Internet Division, ITC, MSTU, Murmansk, Russia
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Ken Bigelow wrote:
>
> Greg wrote:
> >
> > I have been playing with IP Firewall and was wondering if anyone had more
> > info if I used it in the following manner :
> >
> > Basically, i installed ipfw on a webserver (running apache). The server
> > uses ip aliasing for each virtual web. The firewall will be setup
> > to count the packets/bytes per web using commands like this :
> >
> > ipfw add count tcp from any to 204.120.228.197 80
> > ..
Well, if you have a FreeBSD box, there's a firewall built in
the kernel, so it probably runs as fast as at all possible.
(BTW, I've heard there's one for Linux too.)
I don't think this kind of firewall will seriously slow
your system down.
If I got it right, kernel simply looks at each packet that arrives
onto your network interface and then compares it to the firewall
table to decide what to do with it. I tell you this - kernel
must look at every packet it receives no matter if there is a
firewall or not. Every packet still has source and destination IPs
and port numbers that all have to be looked through.
Good luck!
------------------------------------------------------------
Dennis V. Kreminsky hostmaster
Information Technologies Center
voice: (8152) 23-0574 Murmansk State Technical University
fax: (8152) 23-2233 Murmansk, Russia