Yes, your linux box will work fine, and you can dump the traffic going
through with ethereal or other software.

Assuming you have private IPs, and one or a few public IP's, you would set
the linux system to not only forward packets, but also masquearde them.  If
you wanted to have services available to the internet, you can use the
portforwarding module (part of the experimental kernel code.  Turn on the
code maturity options: prompt for incomplete code, or something, in the
first option in your kernel compilation: make menuconfig.  Or just put in
config_experimental=y in the kernel config file

With that said, and your system up and running, how do you analyze traffic?
dumping the network traffic on a well utilized t-1 won't tell you much.
You'll be swamped with data.  I'd suggest looking at some of these
utilities.  I'm sure there are many out there.   I personally have not used
any of these, but perhaps I will have some interest in messing with them:

http://linux.davecentral.com/netmon.html

IPTraf looks interesting.

You can, just with netstat, see who's connected to what at any time.  Use
netstat -M to see masqueraded connections.  IPTraf will do something
similar, but will show you packets/sec, bytes/sec.  It will also show based
on services: web traffic/smtp/streaming video/chat, etc.

Cory

-----Original Message-----
From: Garl R. Grigsby [mailto:[EMAIL PROTECTED]]
Sent: Friday, January 19, 2001 3:55 PM
To: eug-lug
Subject: [EUG-LUG:386] Networking woes.


    I need some advise. I know that there is a lot of networking
experience floating around this group, so I am hoping somebody can help
me.
    My office currently has a T1 link to our main office. over the last
couple of months the usage of this link has steadily increased to the
point where we are running out of bandwidth, which is causing problems
for several apps that need a full time connection to our main office.
The problem is that nobody will admit to being the bandwidth hog. I have
looked at using apps such as Ethereal and Sniffer Lan but all of our
network is all run off of switches which, as I understand it, makes
these devices almost useless.
    My idea is to build a dual nic'd linux box and connect it between
our top level switch and our wan router. With this setup I should be
able to see all of the network traffic that is traveling across the wan
link, right?
    Now for my questions. Will this setup work? What will I have to
setup to forward the traffic from one nic to the other, and still have
ethereal see the traffic. Also how much of a machine will I need for
this? Currently I am looking at using a Pentium Pro 200 with 128 MB of
ram. Does anybody know of a package that would generate a html page of
the T1 usage? Has anybody done this before?

Thanks all,
Garl

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Garl R. Grigsby
Senior Customer Applications Engineering - Analysis Team
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