Re: Router configuration problems

Subject: Re: Router configuration problems
From: Peter M. Bagnall (
Date: Wed Dec 20 2000 - 17:35:52 MST

>I've just had ADSL installed by BT. It terminates on a router so there's no
>PPP involved - just DHCP (to get the address from the router). If I use an
>iBook to get an address assigned I can ping the router from my linux box
>using that address.
>The problem is:
>- how do I get the linux box to request an IP address from the ADSL router
>(via eth0, eth1 is my home network) - I can't seem to get DHCP to work - a
>tcpdump on eth0 suggests its trying bootp

Ok, I've got almost exactly the same setup that you want. So
hopefully I should be able to help! Do you have X running on the
linux box? If so run a utility called netcfg. It's an X config tool.
There's a tab for interfaces. Switch to that and tell eth0 to use
DHCP or BOOTP as appropriate. Activate the interface. That should be
all you need to do there if I remember right. You might want to do a
ifconfig after to check that eth0 is up and has an IP address.

>- how do I set up the routing table once I have a connection. I want to use
>the linux box as a server on but route external traffic to
>ADSL on 192.168.254.x

Note that 192.168.x. is a series of unrouted networks. A router may
not route traffic out from or into one of these networks. My home
network is on 192.168.0. as I suspect is true for many people on this
list. If those networks were routed half the planet would have the
same IP address and all hell would break lose! Instead what you need
to do is use IP masquerading, or IP MASQ. I'd have to look up the
details of how I set this up, But if your kernel has IP MASQ compiled
in it's relatively easy. I did all this in RedHat box, which does
have IP MASQ in by default. I'm not sure that YellowDog does so it's
likely you'll need to compile a kernel (not something I've done
successfully yet!).

A search on Google should get you there. If you need more I'll dig
around for you. (I'm in MacOS at the moment)

I hope that's helpful


Peter M. Bagnall -

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