[plug] Configuring IP Aliaes

[Bernard Blackham]

Mark,

Can I just check what I think you're getting at here. You have one
ethernet LAN on which there are:
  - machines on the 10.0.0.0 network which aren't sposed to see the
    internet
  - a router that receives packets destined for the 203.47.28.xx/xx
    network (are there other 203.47.28.xx machines on the network?)
  - a machine on 10.0.0.154 that you want to have a 203.47.28.148
    address, accessible by both internal clients on one IP and the
    internet on the external IP

Is this correct?

> The internal LAN subnet is 10.0.0.0/255.255.255.0.  I want internal 
> clients to be able to see the machine via 10.0.0.154.  With the alias 
> IP, 203.47.28.148, I want external clients on the internet to see the 
> machine.  

Does your router already route all traffic on 203.47.28.148 to that
network/machine? You can have two subnets on the same physical
network but its not generally regarded as secure.

> Once I've configured the virtual address using eth0:1, what route do I 
> need to add to allow packets destined for the internet to be routed 
> through our router which is 203.47.28.150.  I've been adding the 
> default gateway using the command below.
> 
> route add default gw 203.47.28.150

If the eth0 device has ip 10.0.0.154/255.255.255.0 then there
*should* automatically be entered a route equivalent to:
  route add -net 10.0.0.0 netmask 255.255.255.0 dev eth0
 
This with the default gateway above, should be all you need in the
way of routing. What does your routing table look like at the
moment? 

> However, due to my lack of experience in this, I think the internal 
> packets are also trying to be routed via the router.