Hi folks,
I have a computer with two interfaces: a fixed connection (eth1) and a modem (ppp0). My goal is to receive UDP packets from both connections concurrently (using the recv() function).
The problem is, that the received packets reach the application only when the default gateway is set to that interface's address. For example, if I set the default gw to be in the eth1 subnet, only packets from eth1 reach the application. Other packets are received in the interface (checked using tcpdump), but they seem to be blocked somewhere.
The policy defined in iptables is "ACCEPT" for all incoming packets, with no rules at all.
I would like to know how to overcome this problem, and anyway how is the default gateway related to incoming UDP?

Thanks,
Avishay

The reverse path filter is enabled. For IPv4 the it can be disabled until reboot by:
echo 0 > /proc/sys/net/ipv4/conf/all/rp_filter

Thanks a lot - it seem to solve the problem. I had to do it for each interface separately (/proc/sys/.../<interface name>/rp_filter), though.

Mark the thread as "[SOLVED]" if it's solved.

0 members found this post helpful.