Robert Stone wrote:
> I'm running:-
> Linux roblaptop 4.5.0-2-amd64 #1 SMP Debian 4.5.3-2 (2016-05-08) x86_64 GNU/Linux
That looks like either Testing or Unstable.
> I was running out of room on /dev/sda1 and to make some more space I used
> synaptic to find out the obsolete packages.
> I ended up purging 31 packages and removing 23.
Okay.
> Since that day, each time I boot my laptop, resolv.conf is not created with
> the nameservers and their IP addresses, and consequently I can't connect to
> the outside world via a cable modem.
>
> After booting, running ifdown -a followed by ifup eth0 creates a connection
> and a useable resolv.conf file.
Very strange. What are the contents of this file:
/etc/network/interfaces
Specifically do you have sections for eth0 there? And if so then do
you have sections for "allow-hotplug eth0" or "auto eth0"?
> I have a list of the packages that were deleted. I have been through every
> conceivable package that mentions DHCP or ISC or BIND, etc. by running
> searches via synaptic and ended up replacing some packages.
> For example, libsodium13 is marked as obsolete and I installed libsodium18
> which is the current version.
In your list of packages that were purged or removed was one of them
"network-manager"?
Since you are using a laptop and are also using synaptic I assume you
are an introductory level user and therefore wouldn't have swapped out
from using NetworkManager to using WICD or other manual methods in
/etc/network/interfaces. But in addition to your removing *something*
might have happened such as the installation of something else.
> As well as the resolv.conf issue, I'm unable to run applications locally
> that need to resolve to localhost (127.0.0.1).
Odds are that your 'ifdown -a' command is disabling it. The -a option
downs all interfaces marked auto. Normally the loopback device
127.0.0.1 is marked auto like this in /etc/network/interfaces.
auto lo
iface lo inet loopback
Therefore 'ifdown -a' should down it. You can bring it back up with
'ifup lo' but normally you never want to down it.
> So I'm asking on this forum if anybody has any ideas of where else to look,
> or if anybody has suffered the same issue?
There are a zillion different ways to configure things. Which
usually means needing to play twenty questions in order to determine
what you are doing uniquely on your system. To start that off please
answer these questions:
cat /etc/network/interfaces
dpkg -l | grep -e network-manager -e wicd -e resolvconf
zgrep -e network-manager -e wicd /var/log/dpkg.log*
I suspect you were originally running network-manager but removing
something caused dependencies to install something. The logs should
show what you had before. Restoration requires putting some things
back.
Since you are running either Testing or Unstable and also running out
of disk space I will ask how often you run synaptic's equivalent to
'apt-get clean'? (I never run synaptic so don't know the commands
there. But there should be something equivalent.)
That removes downloaded packages. Otherwise they will build up there
and be a common source of disk space problems.
du -sh /var/cache/apt/archives/
Bob