Tag Archives: netbsd

Networking with a gateway not on the local subnet on NetBSD at OVH

NetBSD has a FAQ for networking that outlines how to do Networking with a gateway not on the local subnet, unfortunately the recipe that they provide doesn't actually work "in the real world." The route command they provide does not make the network stack send an ARP who-has for the IP address and requires that you statically set the MAC address of the gateway.

I figured out a work-around for this, based on some insight from people on the NetBSD tech-talk mailing list. This allows you to use NetBSD as a guest operating system on providers such as OVH and Hetzner:

# ifconfig fxp0 inet 10.0.0.1 
# route add -net 192.168.0.1/32 -cloning -link fxp0 -iface 
# route add default -ifa 10.0.0.1 192.168.0.1

The trick was to specify use route cloning, and use a net definition instead of a host definition. Now NetBSD will send an ARP who-has request for the gateway IP address.

To supplement the OVH bridge client guide that is available on their Wiki, it would fit into the following template:

# ifconfig fxp0 inet Fail.over.IP netmask 255.255.255.255 broadcast Fail.over.IP 
# route add -net Your.Server.IP.254/32 -cloning -link fxp0 -iface 
# route add default -ifa Fail.over.IP Your.Server.IP.254

This should allow you to use NetBSD as a guest and not get blocked by OVH robots that check for too many ARP requests.