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Date:      Wed, 2 Jun 1999 20:32:00 +1000 (EST)
From:      Rowan Crowe <rowan@sensation.net.au>
To:        freebsd-isp@freebsd.org
Subject:   monitoring at the packet level
Message-ID:  <Pine.BSF.4.01.9906022024580.2604-100000@velvet.sensation.net.au>

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Hi all,

I am currently working on a monitoring system which does more than simple
byte counting, it instead monitors connections. Output can be sorted by
most popular source host, most popular destination host, most popular
source port, most popular destination port.

As it's just a test of concept right now, it's basically tcpdump piped to
a program that converts the ASCII output into binary form for its own
internal use. (As a bonus this makes it a little portable, assuming the
target platform has a similar tcpdump)

The problem with tcpdump (and I presume BPF in general) is that it applies
only to specific interfaces - if I have 15 ppp* interfaces this means I'll
need to have 15 BPFs open! I'm concerned about the load on the machine and
the general "non scaleability" of this method.

Obviously a better way would be to snoop on packets as they pass through
the lowest level kernel processing. Perhaps an ipfw tee socket might help
here? I have zero programming experience with tee sockets and very little
with sockets in general - as C is not my normal language of choice I tend
to program from first principles without getting too caught up in system
specific calls. :)

Anyway, I'm posting here in the hope that someone has done something like
this before. TIA...

Cheers.


--
Rowan Crowe                              http://www.rowan.sensation.net.au/
Sensation Internet Services                    http://www.sensation.net.au/
Melbourne, Australia                                 Phone: +61-3-9388-9260



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