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can I setup a dual home machine as a router

asked 2014-08-26 10:30:34 -0600

erenouf gravatar image

I would like to setup a linux software router as part of the environment so a user of that tenant could tcpdump traffic moving between subnets. Currently I'm using Icehouse with Neutron networking using vlans, and what I'm seeing is that hosts can always ping their peers in the collision domain, and if I ping to an address in the next network I can see the echo requests go out, but I never see they never make it to the destination host. So, for example with the following hosts with these connections:

A - B - C

Such that A and C are in different networks, and B is a dual homed host with addresses in both networks. A can ping the "local" interface of B. If A tries to ping C I can tcpdump on the C-side interface of B and see the request packets go out, but I never see them arrive at C.

Similarly if I ping the C-side interface of B from A and tcpdump on the A-side interface I see the echo request and echo reply, but never get the replies back at A.

I'm hoping I just overlooked something simple in the setup to allow me to use B as a router this way (and yes, it has addresses on both sides that are reachable by local hosts, and it has ip_forward enabled, and no firewall rules).

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answered 2014-08-26 14:49:11 -0600

dbaxps gravatar image

updated 2014-08-26 14:49:39 -0600

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Thanks for the tip, but the linux configuration isn't the problem in this case. I've used the same configurations with bare-metal and the linux router works fine, but in openstack the packets are never received at the final destination even though they leave the router correctly.

erenouf gravatar imageerenouf ( 2014-08-27 10:03:56 -0600 )edit

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Asked: 2014-08-26 10:30:34 -0600

Seen: 100 times

Last updated: Aug 26 '14