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 From:  "Chris Bagnall" <chris at minotaur dot it>
 To:  <m0n0wall at lists dot m0n0 dot ch>
 Subject:  ADSL subnet routing where gateway is outside the subnet
 Date:  Thu, 1 Jun 2006 15:34:26 +0100
Greetings all,

I've come across an unusual address range provided by an ISP today and I
wonder if someone might be able to shed some light on the best way to
configure it.

Normally, when I've set up ADSL in the UK with a routed subnet the gateway
tends to be inside that subnet, for example:
In this case, the ISP might assign the ADSL modem .1, then I'd put m0n0 on
.2 (with a gateway of .1), then any PCs that need static IPs get them using
1:1 NAT. I've set up plenty of m0n0s like this and never had a problem.

The ISP I've been dealing with today has given the following ranges:
Fixed WAN IP:
Routed IP Subnet:

The ADSL modem gets via DHCP, all well and good. For m0n0
configuration, is it simply a matter of picking an IP from the .192 subnet
and using the .128 address as the gateway?

Would one need to change any settings on the ADSL modem to ensure it
forwards the subnet correctly? Should the ADSL modem (which is essentially a
router as well) have an address inside the subnet on its LAN side?

Any hints gratefully appreciated.


C.M. Bagnall, Director, Minotaur I.T. Limited
This email is made from 100% recycled electrons