Re: [gentoo-user] resolv.conf is different after every reboot (Got an idea!)

[Grand Duet]

2014-07-27 14:30 GMT+03:00 Grand Duet <grand.duet@×××××.com>:
> 2014-07-27 13:39 GMT+03:00 Walter Dnes <waltdnes@××××××××.org>:
>> On Sun, Jul 27, 2014 at 12:21:23PM +0300, Grand Duet wrote
>>> This is a continuation of the thread:
>>> "Something went wrong with DNS, plz help!"
>>>
>>> Now, the issue became clearer, so I decided to start
>>> a new thread with more descriptive Subject.
>>>
>>> In short: the contents of the file /etc/resolv.conf
>>> is unpredictably different from one reboot to another.
>>> It is either
>>>   # Generated by net-scripts for interface lo
>>>   domain mynetwork
>>> or
>>>   # Generated by net-scripts for interface "eth0"
>>>   nameserver My.First.DNS-Server.IP
>>>   nameserver My.Second.DNS-Server.IP
>>>   nameserver 8.8.8.8
>>>
>>> I tried to chmod this file to be unwrittable even for root
>>> but after a reboot it have been overwritten anyway.
>>>
>> A similar problem was noted at...
>> https://forums.gentoo.org/viewtopic-t-816332-start-0.html
>
> Like in the thread above, I also have a line
>     dns_domain_lo="mynetwork"
> in my /etc/conf.d/net file. It says nothing to me
> and I do not remember how it got there.
>
> But somewhere on Gentoo forum I have found the following
> explanation: "If you only specify dns_domain_lo="foo" and
> restart the lo interface it will put "domain foo" in /etc/resolv.conf
> and remove everything else."
>
> So, I guess I should try to remove that line from my /etc/conf.d/net file.
>
> But why the system worked fine for about a year *with* this line then?

Well, after finishing my main job, I finally got an idea
why everything went wrong after the last system update.

During my last system update, portage instructed me to add
    dev-lang/tk-8.5.15 threads
line to my /etc/portage/package.use file.

Here is the portage message about it:

The following USE changes are necessary to proceed:
 (see "package.use" in the portage(5) man page for more details)
# required by dev-lang/ruby-1.9.3_p484[tk]
# required by dev-ruby/rake-0.9.6[ruby_targets_ruby19]
# required by dev-lang/ruby-2.0.0_p353
# required by dev-ruby/racc-1.4.9[ruby_targets_ruby20]
# required by dev-ruby/rdoc-4.0.1-r1[ruby_targets_ruby19]
=dev-lang/tk-8.5.15 threads

And in my /etc/portage/package.use file this line has already
been commented. So, I just uncommented it. But I do remember
that it was commented for a reason, though do not remember
exactly why.

May be uncommenting that line allowed bringing up
lo and eth0 interfaces *in parallel*. If it is the case,
then I have an easy explanation why the contents
of /etc/resolv.conf file after boot is unpredictable.

If eth0 starts after lo, then I have the right /etc/resolv.conf
file, however if lo starts after eth0, then the DNS IPs in
resolv.conf file are overwritten with dummy instruction
for lo interface.

What do you think?

>>   Can you post the contents of your /etc/conf.d/net
>
> hostname="myhostname"
> dns_domain_lo="mynetwork"
>
> config_eth0="My.Local.IP netmask My.Net.Mask broadcast
> Broadcast.IPof.My.LocalNetwork"
> routes_eth0="default via Local.IPof.My.Gateway"
>
> dns_servers_eth0="My.First.DNS.IP My.Second.DNS.IP 8.8.8.8"
>
> mtu_eth0="1500" # if needed
>
> # The network scripts are now part of net-misc/netifrc
> # In order to avoid sys-apps/openrc-0.12.4 from removing this file,
> this comment was
> # added; you can safely remove this comment.  Please see
> # /usr/share/doc/netifrc*/README* for more information.
>
>> and also the output of the "rc-update show" command?
>
> # rc-update show
>              alsasound | boot
>                bootmisc | boot
>                       dbus |      default
>                      devfs |                       sysinit
>                    dmesg |                       sysinit
>                        fsck | boot
>               hostname | boot
>                  hwclock | boot
>                 keymaps | boot
>                  killprocs |              shutdown
> kmod-static-nodes |                       sysinit
>                        local |      default
>             localmount | boot
>                loopback | boot
>                 metalog |      default
>                modules | boot
>               mount-ro |              shutdown
>                      mtab | boot
>                net.eth0 |      default
>                     net.lo | boot
>              netmount |      default
>                  privoxy |      default
>                    procfs | boot
>                        root | boot
>              savecache |              shutdown
>                       swap | boot
>                swapfiles | boot
>                      sysctl | boot
>                       sysfs |                       sysinit
>       termencoding | boot
>          tmpfiles.dev |                       sysinit
>       tmpfiles.setup | boot
>                       udev |                       sysinit
>           udev-mount |                       sysinit
>               urandom | boot
>
> Everywhere above eth0 has been put instead of its udev "predictable" name.
>
> Do you think that I need
>     carrier_timeout_eth0=20
> somewhere in /etc/conf.d/net ?
>
> Thank you.
>
>> That should help narrow down the potential sources of your problem.