IP Forwarding

[kumaresh_ind]

Hello All,

Is it possible to forward packets from a virtual interface to a real
interface. I have a machine with one interface card and i have created an
alias in that card. This card is connected to the internet. Now i have
connected a PC in the same subnet and apply NAT rules to map the requests
coming to the alias address of the interface (lan0:1) to lan0. Now the PC is
set with the lan0:1 as the gateway. The packets are going from the PC to the
TEST machine, but i do not get any response.

Please can anyone have answers?

Regards
Kumar

[Crist J. Clark]

Doing NAT on a single interface may or may not work well or even at
all. It is not a supported configuration.

As for why this is not working for you, you didn't supply nearly
enough detail about your configuration for anyone to help. About all I
can guess is that you are using Solaris on the router. You see the
packets come from the PC to the router, do you see anything come back
out of the router? Do you see anything in your IPF logs?
--
Crist J. Clark | cjc...@alum.mit.edu
| cjc...@jhu.edu
http://people.freebsd.org/~cjc/ | c...@freebsd.org

[kumaresh_ind]

Thanks Crist.

Actually this is my set up. I am using IPFiter in HP-UX.

-------- ----------------------
| P.C | --->| lan0:1 lan0 | ----> Internet
-------- ---------------------
192.16.1.2 192.16.1.20 15.146.10.20
FIREWALL M/C

Here the two IPs are for the same interface card. But for different aliases.

Now, the gateway for the P.C is the lan0:1 (virtual interface) of the
Firewall machine. The Firewall machine is configured so that the packets
from the P.C through lan0:1 is mapped to lan0. This is the NAT rule.

map lan0 192.16.1.0/24 -> 15.146.10.20/32 portmap tcp/udp 15000:40000

Now the request is leaving through the lan0 properly but the reply is not
reaching the P.C through the lan0:1 back. Am i doing anything wrong here?

Thanks
Kumaresh.