[GLLUG] IP Aliases and routing

Subba Rao sailorn@attglobal.net
Sat, 2 Nov 2002 10:48:5 -0500


We have a Linux PC which has only one NIC with several IP Aliased
addresses.  The aliased addresses are on different subnets.  Th Linux PC
is pretty much behaving like a router.  I can ping all the address from the
actual gateway that is connected to the Linux PC.  All the typical servers
(FTP, Telnet, SMTP, HTTP, Syslog etc.) are running on this Linux PC.

One of the aliased addresses (S.S.S.S) is serving as the syslog server for the gateway.
When I watch the traffic using tcpdump,  the syslog packet makes it to the Linux PC but returned
back (or dropped) because it cannot route it to S.S.S.S.

I have 2 questions for this setup.

1. How do I route the packets on the Linux PC to it's alias address S.S.S.S?

2. Do the Linux servers (FTP,Telnet,SMTP,Syslog.....etc) bind to the actual interface address?
    Or they attached to the IP Aliases as well?

Thank you in advance for any help.

Subba Rao