#define private public - Claus Brod on stuff (11 Oct 2012)

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---+++ [[DefinePrivatePublic20121011ResolvConf][<tt>resolv.conf</tt> vs. Claus - 1:0]] (11 Oct 2012)

<summary>
After upgrading to Ubuntu 12.04, I started seeing pretty funny DNS behavior. For example, I could connect to
a wireless network successfully, but still could not connect to external IP addresses because of DNS resolution
problems. 
</summary>

After a lot of fiddling, I realized that the problem is probably related to [[http://manpages.ubuntu.com/manpages/lucid/man8/resolvconf.8.html][resolvconf]] and its main configuration
file, =/etc/resolv.conf=. On my system, this file sometimes disappears, and sometimes it loses its previous entries.

So far, I have learned that Ubuntu 12.04 indeed introduced a new approach of handling DNS resolution and in particular
the =resolv.conf= file. If my understanding is correct, whenever the system finds a DHCP server, it is supposed to
re-create the =/etc/resolv.conf= file using DNS information it receives via DHCP.

The discussion at http://askubuntu.com/questions/130452/how-do-i-add-a-dns-server-via-resolv-conf hints at similar
problems. But I guess I do not know enough about Ubuntu's networking internals to really understand what is going on,
unfortunately :-(

The following voodoo script sometimes helps me to resurrect =/etc/resolv.conf= with sufficient DNS information
in it. But it drives me mad that I don't have the slightest clue what I am doing there. If you read this and feel
an urge to slap your forehead, feel free to consider me a raving idiot, but do drop me a line to help me educate myself
on this issue. Thanks.

<pre>
#! /bin/bash
pushd /etc
if [[ -r resolv.conf ]]; then
  if [[ ! -L resolv.conf ]]; then
    mv resolv.conf /run/resolvconf
    ln -s /run/resolvconf/resolv.conf
  fi
fi
popd
resolvconf --enable-updates
</pre>

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