Comments | zaitcev: Adventures in tech support

zaitcev

Adventures in tech support

Dec 23, 2021 14:17

OVH was pestering me about migrating my VPS from its previous range to the new (and more expensive) one. I finally agreed to that. Migrated the VM to the new host, it launches with no networking. Not entirely unexpected, but it gets better.

The root cause is the DHCP server at OVH returning a lease with netmask /32. In that situation, it's not ( Read more... )

Comments 3

robbat2 December 25 2021, 09:03:22 UTC

If the DHCP is returning a gateway outside the netmask, have you checked for that being available as pointtopoint, as you'd then be able to use it as the default route fine?

zaitcev December 25 2021, 16:44:36 UTC

Is it possible to set p2p for Ethernet? I thought it only worked for PPP or other interface that has the POINTTOPOINT flag.

robbat2 December 27 2021, 01:15:33 UTC

Quick test w/ VMs shows it working. The key bit if you need to debug it: check w/ arpping if the other host is responding at Layer 2.

host1:
$ ip addr add 10.4.0.4/32 peer 10.4.0.2 dev eth2

host2:
$ ip addr add 10.2.0.2/32 peer 10.4.0.4 dev eth2
$ ping -c 1 10.4.0.4
PING 10.4.0.4 (10.4.0.4) 56(84) bytes of data.
64 bytes from 10.4.0.4: icmp_seq=1 ttl=64 time=1.71 ms

It wouldn't surprise me if DHCP clients don't handle this setup.