[Bug 994227] Re: resolvconf breaks name resolution

[Thomas Hood]

> When I'm done with my wimax network, I just unplug the modem from the
usb port without manual invocation of any command.

The dhclient process for your wimax interface adds nameserver addresses
to the system (via resolvconf) that are accessible over the wimax
interface.  When the wimax interface is disabled, those nameserver
addresses should be removed.  If dhclient doesn't do this automatically
you may have to help it by stopping the process gracefully.  See
dhclient(8), especially the part about the -r and -x options.

What's mysterious about the behavior your originally reported is (IIUC)
that the dhclient process for wlan0 adds nameserver addresses and then
removes them a few seconds later.  Have you figured out why this
happens?

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https://bugs.launchpad.net/bugs/994227

Title:
  resolvconf breaks name resolution

Status in “resolvconf” package in Ubuntu:
  Incomplete

Bug description:
  While resolvconf daemon is running, I cannot use the network, because
  my resolv.conf file is filled with invalid nameservers soon after
  connection:

  ========================== bash session: ==========================
  # service resolvconf status
  resolvconf start/running
  # file /etc/resolv.conf
  /etc/resolv.conf: symbolic link to `../run/resolvconf/resolv.conf'
  # export LC_ALL=C;\
    date;\
    dhclient wlan0;\
    cat /etc/resolv.conf;\
    date;\
    inotifywait /etc/resolv.conf;\
    date;\
    cat /etc/resolv.conf
  Fri May  4 00:50:48 MSK 2012
  Rather than invoking init scripts through /etc/init.d, use the service(8)
  utility, e.g. service smbd reload

  Since the script you are attempting to invoke has been converted to an
  Upstart job, you may also use the reload(8) utility, e.g. reload smbd
  RTNETLINK answers: File exists
  # 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 192.168.129.129
  nameserver 8.8.8.8
  nameserver 94.25.128.74
  Fri May  4 00:50:50 MSK 2012
  Setting up watches.
  Watches established.
  /etc/resolv.conf OPEN
  Fri May  4 00:52:44 MSK 2012
  # 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 94.25.128.74
  nameserver 94.25.208.74

  =============================================================================

  To clarify servers:
  192.168.129.129 is my ISP DNS
  8.8.8.8 backup server configured in my router
  94.25.128.74… first wimax0 DNS, invalid in my current wlan0 network

  # cat /run/resolvconf/interface/wimax0.dhclient 
  nameserver 94.25.128.74
  nameserver 94.25.208.74
  # ifconfig wimax0
  wimax0: error fetching interface information: Device not found
  # ifdown wimax0
  ifdown: interface wimax0 not configured

  The delay until resolv.conf gets corrupted is not constant at all, sometimes it's as small as 3 seconds. one time is was 13 seconds.
  If I reconnect and shut down resolvconf, I get a working network without any problems. This behavior seems to be a regression after apt-get upgrade from ubuntu 11.10 and seems to be a blocker to an ordinary user, since the network is effectively unusable.

  ProblemType: Bug
  DistroRelease: Ubuntu 12.10
  Package: resolvconf 1.63ubuntu12
  ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
  Uname: Linux 3.2.0-23-generic x86_64
  ApportVersion: 2.0.1-0ubuntu7
  Architecture: amd64
  Date: Thu May  3 23:57:11 2012
  PackageArchitecture: all
  ProcEnviron:
   LANGUAGE=
   TERM=xterm
   PATH=(custom, user)
   LANG=ru_RU.UTF-8
   SHELL=/bin/bash
  SourcePackage: resolvconf
  UpgradeStatus: No upgrade log present (probably fresh install)

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