[Bug 1717995] Re: extra domains not removed from resolv.conf when VPN disconnects

Sat Sep 30 10:42:21 UTC 2017

I'm experiencing this same issue.

A workaround that works for me is to remove my vpn domain from
/etc/resolv.conf. The last line of this file looks as follows after a
successful VPN connection:

search Home myvpndomain

where the last term is the domain of my vpn (vpn.bla.com). The workaround is to remove it and leave:
search Home
then restart the network-manager service and the VPN reconnects. 

Otherwise I have to restart the computer to be able to connect to the
VPN after a successful connection. I mean: after a computer restart, VPN
always connects, but if I disconnect I cannot reconnect to the VPN
unless I restart the computer or do the workaround.

I have a big confusion on how /etc/resolv.conf is managed nowadays in
Ubuntu. I have at least three different system processes generating a
resolv.conf.

systemd-resolved:
/run/systemd/resolve/resolv.conf 

network-manager:
/run/NetworkManager/resolv.conf

and resolvconf:
/run/resolvconf/resolv.conf

My actual /etc/resolv.conf is a symbolic link to this last one. At some
point I tried to have only network-manager manage /etc/resolv.conf.
Everything works fine, but when I connect to VPN it can't resolve any
DNS outside of the private network.

The resolv.conf generated by systemd-resolved has the same problem as
the one generated by resolvconf, when the VPN reconnects the VPN domain
is not removed from the "search" line.

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https://bugs.launchpad.net/bugs/1717995

Title:
  extra domains not removed from resolv.conf when VPN disconnects

Status in systemd package in Ubuntu:
  In Progress

Bug description:
  I use a VPN (network manager "vpnc" config) to connect to my work
  network.  The gateway is "webvpn.purestorage.com".  When I connect, I
  get "purestorage.com" added to the "search" line in my
  /etc/resolv.conf (and /run/resolvconf/interface/systemd-resolved) -
  which makes perfect sense, the VPN passes this info to me and then I
  can connect to systems within the work network without having to use a
  FQDN.

  The bug (which is a regression from older versions of Ubuntu) is that
  when I lose my connection to the VPN (either because I disconnect
  explicitly, or because the network goes down or I suspend my laptop),
  the "purestorage.com" domain is not removed from those "search" lines.
  And for some reason this prevents me from resolving
  webvpn.purestorage.com (which prevents me from reconnecting to the
  VPN).

  In particular, if I connect and disconnect my VPN, I get:

   $ systemd-resolve webvpn.purestorage.com
  webvpn.purestorage.com: resolve call failed: No appropriate name servers or networks for name found

  If I then edit /etc/resolv.conf by hand to remove all the
  purestorage.com entries from the search line - in other words, change

   $ cat /etc/resolv.conf 
  # 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
  # 127.0.0.53 is the systemd-resolved stub resolver.
  # run "systemd-resolve --status" to see details about the actual nameservers.

  nameserver 127.0.0.53
  search home.digitalvampire.org purestorage.com dev.purestorage.com

  to

   $ cat /etc/resolv.conf 
  # 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
  # 127.0.0.53 is the systemd-resolved stub resolver.
  # run "systemd-resolve --status" to see details about the actual nameservers.

  nameserver 127.0.0.53
  search home.digitalvampire.org

  and change nothing else, then:

   $ systemd-resolve webvpn.purestorage.com
  webvpn.purestorage.com: 192.30.189.1
                          (vpn.purestorage.com)

  -- Information acquired via protocol DNS in 25.9ms.
  -- Data is authenticated: no

  I'm not sure if the bug is in systemd, network manager, or some other package, but I'm happy to try any debugging that is helpful to resolve this (no pun intended).

  ProblemType: Bug
  DistroRelease: Ubuntu 17.10
  Package: systemd 234-2ubuntu10
  ProcVersionSignature: Ubuntu 4.12.0-13.14-generic 4.12.10
  Uname: Linux 4.12.0-13-generic x86_64
  ApportVersion: 2.20.7-0ubuntu1
  Architecture: amd64
  CurrentDesktop: GNOME
  Date: Mon Sep 18 11:20:17 2017
  InstallationDate: Installed on 2016-09-01 (381 days ago)
  InstallationMedia: Ubuntu 16.10 "Yakkety Yak" - Alpha amd64 (20160901)
  MachineType: LENOVO 20FRS2FK00
  ProcEnviron:
   TERM=screen
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.12.0-13-generic root=UUID=30d5ada5-835d-4cf7-96cf-3329c0316107 ro quiet splash vt.handoff=7
  SourcePackage: systemd
  UpgradeStatus: Upgraded to artful on 2017-07-26 (53 days ago)
  dmi.bios.date: 07/13/2017
  dmi.bios.vendor: LENOVO
  dmi.bios.version: N1FET53W (1.27 )
  dmi.board.asset.tag: Not Available
  dmi.board.name: 20FRS2FK00
  dmi.board.vendor: LENOVO
  dmi.board.version: SDK0J40697 WIN
  dmi.chassis.asset.tag: No Asset Information
  dmi.chassis.type: 31
  dmi.chassis.vendor: LENOVO
  dmi.chassis.version: None
  dmi.modalias: dmi:bvnLENOVO:bvrN1FET53W(1.27):bd07/13/2017:svnLENOVO:pn20FRS2FK00:pvrThinkPadX1Yoga1st:rvnLENOVO:rn20FRS2FK00:rvrSDK0J40697WIN:cvnLENOVO:ct31:cvrNone:
  dmi.product.family: ThinkPad X1 Yoga 1st
  dmi.product.name: 20FRS2FK00
  dmi.product.version: ThinkPad X1 Yoga 1st
  dmi.sys.vendor: LENOVO

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