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I tweaked my system by installing ftp server and a dns server. I think in the process I messed up resolv.conf and the hosts file.

Now I want to restore it but am not able to do so. I am using ubuntu 14.04 x86_64.

Here is a screenshot that might help:

enter image description here

Seth
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pritamprasad
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  • Could you post the instructions you followed and the current content of related config files hosts...? – user.dz Jun 12 '14 at 10:02
  • i added 127.0.1.1 myname to the resolv.conf file.. everything was fine then i rebooted and everything gone. – pritamprasad Jun 12 '14 at 10:06
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    Resolv.conf is generated file, sure you have seen this at top of it # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN. See https://askubuntu.com/questions/130452/how-do-i-add-a-dns-server-via-resolv-conf/130459#130459 – user.dz Jun 12 '14 at 10:12
  • You should include in your question the version of Ubuntu you are using and whether it is a server version or a desktop (GUI) version. – steeldriver Jun 12 '14 at 11:54

2 Answers2

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If you are running a currently-supported desktop version of Ubuntu, then networking should be handled by the NetworkManager service, and your /etc/network/interfaces file should contain only the default loopback interface definition

auto lo
iface lo inet loopback

To fix your /etc/resolv.conf file, you probably need to reconfigure the package from the command line using

sudo dpkg-reconfigure resolvconf

It will present you with a question about preparing /etc/resolv.conf for dynamic updates - answer "Yes". It may also present you with another question about temporarily appending your existing config to the dynamic one - if so you should probably answer "No" to that one. This will re-create the default symbolic link in place of your manually-edited file.

steeldriver
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Edit your /etc/network/interfaces with the correct settings. 

sudo nano /etc/network/interfaces

Then restart your network device:

sudo ifdown eth0 && sudo ifup eth0

The resolv.conf will be recreated with the correct settings.

You can put the following in your hosts file if you want the defaults back:

127.0.0.1 localhost
127.0.1.1 hostname

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts

The second line is only needed if your pc has a name. (Don't forget to substitue the name).

j.raymond
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Pabi
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  • in my case i have wlan1, as i am using network through this, but the command [sudo ifdown wlan1 && sudo ifup wlan1] do not work for me.... it is giving error as [ignoring unknown interface] – pritamprasad Jun 12 '14 at 11:11
  • Can you post the output or a screenshot of the output from sudo ifconfig and sudo ifdown wlan1 – Pabi Jun 12 '14 at 11:16