Using Bluetooth PAN leaves broken resolv.conf

[Mikko Rauhala]

Having paired an Android phone, the network manager menu in Unity displays the "GT-I9300 Network" appropriately and I can tether over the phone's mobile broadband just fine.

However, the PAN's nameserver setting is put directly into /etc/resolv.conf (instead of doing the dnsmasq thing) _and_ is left there, like so, even after disconnecting and connecting to a different (WiFi) network:

# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 192.168.44.1
nameserver 127.0.1.1

(The 127.0.1.1 part isn't there before connecting to WiFi, it is added at that point, but the now-defunct BT PAN nameserver address persists.)

This greatly interferes with DNS queries.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: network-manager 0.9.8.8-0ubuntu7
ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
CRDA: Error: [Errno 2] No such file or directory: 'iw'
CurrentDesktop: Unity
Date: Wed Nov 5 19:23:27 2014
IpRoute:
 default via 192.168.0.1 dev wlan0 proto static
 192.168.0.0/24 dev wlan0 proto kernel scope link src 192.168.0.17 metric 9
NetworkManager.state:
 [main]
 NetworkingEnabled=true
 WirelessEnabled=true
 WWANEnabled=true
 WimaxEnabled=true
SourcePackage: network-manager
UpgradeStatus: No upgrade log present (probably fresh install)
WifiSyslog:

nmcli-dev:
 DEVICE TYPE STATE DBUS-PATH
 4C:BC:A5:EC:12:83 bluetooth disconnected /org/freedesktop/NetworkManager/Devices/4
 wlan0 802-11-wireless connected /org/freedesktop/NetworkManager/Devices/1
 eth0 802-3-ethernet unavailable /org/freedesktop/NetworkManager/Devices/0
nmcli-nm:
 RUNNING VERSION STATE NET-ENABLED WIFI-HARDWARE WIFI WWAN-HARDWARE WWAN
 running 0.9.8.8 connected enabled enabled enabled enabled enabled

[Mikko Rauhala (mjr-iki)]

After having to had to remove the extra line manually a couple of times, this morning when I disconnected, I found that it wasn't there. So it doesn't appear to happen all the time.

I'm not sure if the line was there to begin with while using the connection, or did the DNS setup go through dnsmasq as it's supposed to this time. I'll check during my subsequent use.

[Mikko Rauhala (mjr-iki)]

Okay, so now I verified that the nameserver was added to resolv.conf. Then I rechecked before disconnecting and noted that the extra resolv.conf entry had disappeared (without changes to network configuration in the meanwhile). nm-tool reported the correct nameserver address still, and it seemed to work through the local proxy (one presumes). So the generated resolv.conf entry seems both unnecessary and possibly transient, though as said, it has persisted beyond disconnecting the Bluetooth PAN at least two times.

Everything working even without the entry indicates that it probably shouldn't be generated at all.