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Date:      Mon, 21 Feb 2000 22:50:11 -0800
From:      Thomas Hargrove <ciagon@quiknet.com>
To:        freebsd-questions@FreeBSD.ORG
Subject:   FreeBSD as a router
Message-ID:  <001801bf7d01$10e2c6c0$0201000a@yourmom.dhs.org>

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    My roommate and I currently have 3 connections to the internet (2 DSL
lines and one cable modem connection).  We also have 3 independent gateways
on each line doing NAT for us (2 are FreeBSD, one is Linux Mandrake 7.0).
The 3 gateways do NAT for about 10 Windows machines on the internal network.
Our problem lies in the fact that when you configure DHCP to give out more
than one default gateway to Windows machines the system relies on the
Windows machine to change when it's primary default gateway goes down.  This
doesn't work well (trust me from experience... we've been using this system
for about a month).  So, what we need is a way to change routes to the
internet (through the gateways) so that when we take down one of the
gateways for maintenance, the Windows machines start routing off a different
gateway (connection to the internet).
    Here's our solution to the problem (that again doesn't fully work):  We
set up a 4th machine (with FreeBSD, naturally) and set it as the default
gateway under DHCP for all the Windows machines.  That way there's only one
machine that we have to change the routes on.  Also, this machine will be
super stable because it will only having a couple processes running and
because we do our development on our main FreeBSD gateway (77 GB
fileserver/gateway).  So, our problem is setting up this 4th machine to
route off different gateways depending on:
    a) which Windows machine initiates the connection (i.e.. we want to
route our neighbors off the Linux box and us off the main FreeBSD machine)
    b) which gateway is up and stable (sometimes the gateway might have just
come back up, but only for a few seconds as we make a quick change and then
reboot, so we need a way to say don't change the route unless this gateway
has been up and stable for an hour or so)
    c) (optional) which gateway currently has the fastest connection to the
internet

    I don't believe this has been tried with a FreeBSD machine before and
probably could be implemented relatively easily with a Cisco router or
something similar, but unfortunately my roommate and I don't have the funds
for something that extravagant (or expensive, for that matter).

Here's the breakdown of IP's and such on our local network:

BSD Fileserver (our DSL)    10.0.1.11
    running DHCP, NAT, DNS, Apache

Linux Mandrake 7.0 (neighbors DSL)    10.0.1.1
    running NAT

BSD secondary gateway (cable modem)    10.0.1.101
    running NAT

BSD Main Gateway     10.0.1.111


    Also, if anyone knows how to run a FreeBSD machine as a backup DCHP or
DNS server, I'd love to know how to do that too.  Thanks for the help!!!



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