DNAT sends packed by wrong interface

Manuel Mollar Villanueva <mm@xxxxxxxxxx> · Sat, 20 Nov 2004 00:30:24 +0100

Hi,
I have encountered a problem when using DNAT:

Scenario:

iptables v1.2.7a
Linux 2.4.20

Computer A:

  eth0 ip 150.128.49.236/21

  eth1 ip 10.1.1.1/24

  iptables -t nat -A PREROUTING -d 150.128.49.236 -p tcp --dport 8080 
-j DNAT --to-destination 10.1.1.2:80

Computer B:
 eth0 connected to eth1 of computer A, ip 10.1.1.2

Client C:
 ip 213.171.249.250
 When accessing port 8080 of A is redirected to port 80 on B,  OK

Client D:

 ip 150.128.49.219, in the SAME NETWORK of A (eth0)

 When connecting to A, port 8080, the configured DNAT redirects the 
packets to 10.1.1.2:80 , BUT PACKETS ARE SENT to interface ETH0, not to 
interface eth1 as expected, so , do not arrive to B.

 The same problem occurs for any client in the network of A

Some idea?

Thanks