/etc/init/network-interface.conf makes it impossible to have persistent PPP connection

[Christian Hudon]

I have a server with a static PPP connection to the Internet. (It's a PPPoE connection to an ISP, actually.) I want said PPP connection to come up on boot and then *always stay up* (unless I take it down temporarily myself for sysadmin work, obviously). This used to be possible with hardy, but now doesn't work at all with lucid unless I hack /etc/init/network-interface.conf. Otherwise when say the other side closes the connection, it doesn't get restarted.

I have my PPP connection configured with "persist" and "maxfail 0". I also have a script / upstart conf file to restart the pppd program if it terminates unexpectedly, but I don't think that impacts this bug report. Here's the root of the problem, to the best of my understanding. When the PPP connection is stopped, the kernel destroys the ppp0 interface. Upstart sees this and the network-interface.conf then calls "ifdown ppp0", and so whatever the pppd daemon was going to do beforehand (restart the connection, for instance), now it's being stopped. I commented out the "ifup" and "ifdown" lines in network-interface.conf, and now my PPP connection restarts properly when it's interrupted.

I believe the solution would involve only doing ifup/ifdown calls in network-interface.conf for network interfaces that are actual hardware being plugged in on an actual physical bus in the computer. At least I know that udev also has a set of "ifup" and "ifdown" calls deep in its bowels, but these don't cause problem for my PPP connection, so udev must be doing something different there...

[Stéphane Graber (stgraber)]

ifdown should only be called if the interface is marked as "auto" in /etc/network/interfaces, in your case, it really shouldn't be.

Can you attach your /etc/network/interfaces, your upstart job and any other relevant config?

[FrankAu (terabite-4)]

I have encountered the same issue - with a thread in the forums as ...

   [ubuntu] pppd drops link frequently after LTS Server upgrade from 8.04 Hardy to Lucid 10.04
   http://ubuntuforums.org/showthread.php?t=1918431

... and discovered a related bug report ...

   udev stops pppd persist working
   https://bugs.launchpad.net/ubuntu/+source/ifupdown/+bug/78043

As of this morning the "restart" of pppd still refuses to happen ... now working on understanding how to switch on enough logging to see who has the penchant throwing the toys out of the sandpit!