Asymmetric routing with FreeBSD on Amazon EC2 within VPC

Adrian Chadd adrian at
Wed May 20 03:56:35 UTC 2015


So the "freebsd clean" solution would be to create two listen sockets,
one per IP address, and and have each IP address / routing table in a
separate FIB, or separate vnet.

I don't know if anyone has set that up though. It would be nice to
teach some web servers and proxy serversabout FreeBSD FIBs.


On 19 May 2015 at 12:22, Patrick Gibson <gibblertron at> wrote:
> I'm wondering if anyone has managed to figure out a way to have an
> Amazon EC2 instance behind a VPC work with multiple public IP
> addresses? The issue is with asymmetric routing. It's been resolved in
> the Linux world
> (,
> but I can't seem to get it working under FreeBSD. Using the setfib
> command, I'm able to manually go out through either interface, but for
> incoming packets to a webserver that listens to both interfaces, no
> dice. :(
> Patrick
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