[Gllug] ADSL, NAT, IPMasqerade

Paul Brazier pbrazier at cosmos-uk.co.uk
Thu Apr 18 16:11:27 UTC 2002

> The static addresses I have are in the range 217.xxx.xxx.xxx 
> and I use 192.168.xxx.xxx for my local network.
> Now after much googling I think I need to fit 2 ethernet 
> cards into the firewall box, one with a 217 address and one 
> with a 198 address.
> Then I need to use IPMasqerading to translate between the 2.
> I have used IPMasq before but that was with a modem (i.e. 
> dynamically assigned address) and all my PC's had 192 
> addresses - now I'm confused.
> Am I going in the right direction or am I or barking up the 
> wrong tree (or perhaps just barking).

Sounds OK, it should be just the same in theory as with a modem except
instead of the ppp0 (modem)interface you have a second eth (ethernet)
interface, eth1 on the firewall box.
When you had the modem it would have been the modem itself that had the
external "real" IP address.
I have a box that acts as a kind of firewall - one interface is ppp0 a
USB modem with a real fixed IP address and the other is eth0 an ethernet
card with a 192.168... IP address. And the other box accesses the
internet via this using IP masquerading.
Then I think if you want several IP addresses coming in to your eth1
external interface you can have virtual interfaces eth1, eth1:0, eth1:1,


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