Multiple interfaces with same ip address

Bruce Cran bruce at
Sat Jul 12 14:40:43 PDT 2003

I've read that having the same ip/netmask assigned to multiple NICs isn't
supported in FreeBSD, due to problems with routing.   I have a setup where I'd
like to have rl0, wi0, tun0 and tun1 having the same ip on a /29 subnet, 
is there some way of achieving this?   
I've heard about interface aliasing, but that doesn't
seem to solve the problem, since it's assigning multiple ips to one interface.
I've got it working at the moment, but am wondering if there's a better way
of configuring the system.

One problem I'm having is I'm running routed across the interfaces, and 
it looks as though it doesn't like the same ip assigned to 
multiple interfaces - I get

IP_ADD_MEMBERSHIP ALLHOSTS: Can't assign requested address
setsockopt(IP_ADD_MEMBERSHIP RIP): Can't assign requested address

these appear benign, since RIP does seem to work, but I got a similar message
when running the zebra routing daemon, which proved fatal.

I'd welcome any hints or advice people might have 
about how I should be configuring the interfaces and routing.

Bruce Cran

More information about the freebsd-questions mailing list