[nSLUG] Multiple IPs with Eastlink

mcurrie mcurrie at buzz.cs.dal.ca
Mon Feb 18 13:08:19 AST 2002

Eastlink has told me that they cannot map multiple IP addresses to one hwaddr.
 I need to firewall 4 IP addresses from Eastlink and do not want to set up 4 
firewalls.  I can't put more than one physical ethernet card on a subnet.  
I've tried that, it doesn't work properly.  With MTT i used IP aliasing (eth0, 
eth0:0, eth0:1, etc.) and it works beautifully.  I can't do this with Eastlink 
because the hwaddr remains the same for each alias.
I have been playing with dummy interfaces in hopes of resolving my problem.  I 
have created a dummy interface on my local network and it works fine.  I can 
ping it and it can ping the local network.  I can assign it the MAC address of 
a known ethernet card that is not in use (it isn't even in a computer).  When 
I create a dummy interface on the Eastlink side, specifying a registered 
hwaddr/IP pair, the dummy interface doesn't respond.  It can ping itself and 
nothing else.  I added the dummy interface to the routing table and updated 
arp via arp -s xxx.xxx.xxx.xxx FF:FF:FF:FF:FF:FF.
Both the IP of the dummy interface and the IP of the real external interface 
are on the same subnet (this may be the problem but I don't know).  Does 
anyone have any ideas as to how I can either configure the dummy interface to 
work OR a different solution to my multiple IP problem with Eastlink?

More information about the nSLUG mailing list