[Resolvconf-devel] Bug#628524: Bug on purge and reinstall

[Thomas Hood]

> there seems to be a nasty bug when resolvconf
> is installed, purged and installed again.

Here is what happens, assuming no nameserver information
suppliers yet include resolvconf dpkg-event hook scripts.

Debian system boots up.  Some interface configurer configures
a network interface and obtains an external nameserver address.
Dnsmasq starts.

* /etc/resolv.conf lists both external nameserver address
  and loopback address (for dnsmasq)

Install resolvconf

* /run/resolvconf/interface/original.resolvconf lists both addresses
* /etc/resolv.conf lists both addresses
* /var/run/dnsmasq/resolv.conf lists both addresses[*]

Resolvconf update

* /run/resolvconf/interface/original.resolvconf lists both addresses
* /etc/resolv.conf lists only loopback address
* /var/run/dnsmasq/resolv.conf lists both addresses[*]

Purge resolvconf

* /etc/resolv.conf lists only loopback address
* /var/run/dnsmasq/resolv.conf lists both addresses, but
dnsmasq will no longer look at this file if it is restarted.

Install resolvconf

* /run/resolvconf/interface/original.resolvconf lists only loopback address
* /etc/resolv.conf lists only loopback address
* /var/run/dnsmasq/resolv.conf lists only loopback address

End.  The external nameserver address has been lost.

The only solution is to reboot.

[*] This is already wrong.  The loopback address should not be included
in /var/run/dnsmasq/resolv.conf.  However, dnsmasq ignores loopback
addresses so no great harm done.