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I am not a big Ubuntu guru, running 12.04 LTS version. I need to connect via vpnc from university to the work network. Logging in works fine, however I cannot reach any machine behind the VPN. Also, my internet still works w/o me setting up the work proxy. Any help is highly appreciated!

This is my /etc/resolv.conf before connecting:

# 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 127.0.0.1
search [university-domain]

And this is the same file after connection has been set up:

# 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 127.0.0.1
search [university-domain] [work-domain]

From looking at other resov.conf contents on my colleagues' machines, the nameserver is not updated to the one within the work network. This is how my colleagues' resolv.conf looks:

# Generated by NetworkManager
domain [work-domain]
search [work-domain]
nameserver 147.243.4.86
nameserver 147.243.4.70
nameserver 147.243.1.52
# NOTE: the libc resolver may not support more than 3 nameservers.
# The nameservers listed below may not be recognized.
nameserver 147.243.1.53
nameserver 147.243.128.216
nameserver 147.243.128.217

My colleague runs an older Ubuntu version (11.04 I guess).

Please let me know!

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I think you missed a key line... NetworkManager created your colleague's resolv.conf... –  Thomas W. Jul 6 '12 at 18:10
    
Sorry, I don't get it @LordofTime... what are do you mean? –  konstantin Jul 7 '12 at 10:23
    
well, with your colleagues machines, they're using networkmanager, the automated network manager that is part of the Ubuntu GUI, to set up everything. Is there a particular reason you are setting your resolv.conf stuff manually? –  Thomas W. Jul 7 '12 at 14:02
    
@LordofTime I'm not. I use the same frontend for configuring and connecting to VPN as my colleagues. My understanding is that Ubuntu 12.04 uses resolvconf instead of NetworkManager (see here: stgraber.org/2012/02/24/dns-in-ubuntu-12-04). May be that is the malfunctioning bit. –  konstantin Jul 8 '12 at 20:25

1 Answer 1

Your /etc/resolv.conf looks correct both before and after you connect, assuming that you have a local forwarding nameserver running which listens at 127.0.0.1. In Ubuntu 12.04 Desktop such a nameserver is running by default. To see the nameserver process, run

ps -elf|grep dnsmasq

The reason your colleague's /etc/resolv.conf looks different is that your colleague is not running a local forwarding nameserver. Also, your colleague does not have the resolvconf package installed and so your colleague's NetworkManager process is writing directly to /etc/resolv.conf instead of using resolvconf for that purpose.

On your machine, addresses for work LAN nameservers should not appear in /etc/resolv.conf. That should continue to show only "nameserver 127.0.0.1" (or "nameserver 127.0.1.1" in Ubuntu 12.10.) The work LAN nameserver addresses should be sent by NetworkManager to the local forwarding resolver to use as forwarding addresses. To see what addresses have been sent, do

nmcli -f IP4 dev list | grep DNS

In Ubuntu 12.04 the addresses can also be seen in /run/nm-dns-dnsmasq.conf but in Ubuntu 12.10 the addresses are sent from NM to dnsmasq over D-Bus and so can't be inspected that way.

In the original question it is not even clear that the problem is DNS-specific. Does the questioner have any network connectivity at all with the work LAN? Can the questioner ping IP addresses on the work LAN?

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