[libvirt-users] Problems with VM networking on Ubuntu Quantal

Dale Amon amon at vnl.com
Wed Jan 2 11:10:36 UTC 2013


I have shifted some VM's to a new server running Quantal
and have had a world of trouble. The first one was caused
by issues with an apparently compiled in path in their
apparmor version which forced VM pools to be in /srv or
similar rather than where I wanted them. For now this was
not a big issue, and thankfully the server where it would
be a big time problem (there are individual drives per
major customer or user) is Debian.

But... I still have issues. The networking has changed
considerably and although I can get my VM running, I cannot
reach it.

The new quantal machines give you something like this:

br0       Link encap:Ethernet  HWaddr ****
          inet addr:10.0.0.xx  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: *****/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1

p6p1      Link encap:Ethernet  HWaddr ****
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

virbr0    Link encap:Ethernet  HWaddr ****
          inet addr:192.168.122.1  Bcast:192.168.122.255  Mask:255.255.255.0
          UP BROADCAST MULTICAST  MTU:1500  Metric:1

vnet0     Link encap:Ethernet  HWaddr fe:54:00:84:3c:4f  
          inet6 addr: fe80::fc54:ff:fe84:3c4f/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

The VM machine has a static ip on the same network, ie 10.0.0.x. It
worked fine on the old server but is not reachable (and cannot
connect outward).

Forwarding is turned on:
	cat /proc/sys/net/ipv4/ip_forward 
	1

The VM has

eth0      Link encap:Ethernet  HWaddr ****
          inet addr:10.0.0.xx  Bcast:10.0.0.255  Mask:255.255.255.0
          inet6 addr: *****/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1

An attempt to ping from the VM to anything outside gives a "Destination 
host unreachable" message.

It has been a long time since I set the old machine up, so I
may well have forgotten some step. 





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