[Bug 1926143] [NEW] DNS resolution faulty over openconnect

[Karl Kastner]

Public bug reported:

When connected over VPN, then some domain names are incorrectly
resolved. In particular HTTPS/SSL is not working for many sites. Steps
to reproduce:

1) Connect to a vpn via openconnect

2) Lookup an address:

nslookup www.bing.com
Server:		127.0.0.1
Address:	127.0.0.1#53

Non-authoritative answer:
Name:	www.bing.com
Address: 145.253.3.148
Name:	www.bing.com
Address: 2a01:860:0:210::1:0

Which is wrong. Whois shows that this is actually an address of a
backbone server used by my provider.

Workaround:

3) Deactivate automatic updates to resolv.conf with sudo dpkg-reconfigure resolvconf
4) Add the line: nameserver 8.8.8.8 to /etc/resolvconf/resolv.conf.d/head
5) run sudo resolvconf -u
6) Verify DNS resolution:

nslookup www.bing.com
Server:		8.8.8.8
Address:	8.8.8.8#53

Non-authoritative answer:
www.bing.com	canonical name = a-0001.a-afdentry.net.trafficmanager.net.
a-0001.a-afdentry.net.trafficmanager.net	canonical name = www-bing-com.dual-a-0001.a-msedge.net.
www-bing-com.dual-a-0001.a-msedge.net	canonical name = dual-a-0001.a-msedge.net.
Name:	dual-a-0001.a-msedge.net
Address: 204.79.197.200
Name:	dual-a-0001.a-msedge.net
Address: 13.107.21.200
Name:	dual-a-0001.a-msedge.net
Address: 2620:1ec:c11::200

Which returns the correct ip address.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: resolvconf 1.82
Uname: Linux 5.8.0-050800-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Mon Apr 26 11:21:43 2021
InstallationDate: Installed on 2015-11-05 (1999 days ago)
InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
PackageArchitecture: all
SourcePackage: resolvconf
UpgradeStatus: Upgraded to focal on 2020-09-10 (228 days ago)
modified.conffile..etc.apport.crashdb.conf: [modified]
mtime.conffile..etc.apport.crashdb.conf: 2019-03-07T14:28:39.455024

** Affects: resolvconf (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: amd64 apport-bug focal

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https://bugs.launchpad.net/bugs/1926143

Title:
  DNS resolution faulty over openconnect

Status in resolvconf package in Ubuntu:
  New

Bug description:
  When connected over VPN, then some domain names are incorrectly
  resolved. In particular HTTPS/SSL is not working for many sites. Steps
  to reproduce:

  1) Connect to a vpn via openconnect

  2) Lookup an address:

  nslookup www.bing.com
  Server:		127.0.0.1
  Address:	127.0.0.1#53

  Non-authoritative answer:
  Name:	www.bing.com
  Address: 145.253.3.148
  Name:	www.bing.com
  Address: 2a01:860:0:210::1:0

  Which is wrong. Whois shows that this is actually an address of a
  backbone server used by my provider.

  Workaround:

  3) Deactivate automatic updates to resolv.conf with sudo dpkg-reconfigure resolvconf
  4) Add the line: nameserver 8.8.8.8 to /etc/resolvconf/resolv.conf.d/head
  5) run sudo resolvconf -u
  6) Verify DNS resolution:

  nslookup www.bing.com
  Server:		8.8.8.8
  Address:	8.8.8.8#53

  Non-authoritative answer:
  www.bing.com	canonical name = a-0001.a-afdentry.net.trafficmanager.net.
  a-0001.a-afdentry.net.trafficmanager.net	canonical name = www-bing-com.dual-a-0001.a-msedge.net.
  www-bing-com.dual-a-0001.a-msedge.net	canonical name = dual-a-0001.a-msedge.net.
  Name:	dual-a-0001.a-msedge.net
  Address: 204.79.197.200
  Name:	dual-a-0001.a-msedge.net
  Address: 13.107.21.200
  Name:	dual-a-0001.a-msedge.net
  Address: 2620:1ec:c11::200

  Which returns the correct ip address.

  ProblemType: Bug
  DistroRelease: Ubuntu 20.04
  Package: resolvconf 1.82
  Uname: Linux 5.8.0-050800-generic x86_64
  ApportVersion: 2.20.11-0ubuntu27.16
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: ubuntu:GNOME
  Date: Mon Apr 26 11:21:43 2021
  InstallationDate: Installed on 2015-11-05 (1999 days ago)
  InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
  PackageArchitecture: all
  SourcePackage: resolvconf
  UpgradeStatus: Upgraded to focal on 2020-09-10 (228 days ago)
  modified.conffile..etc.apport.crashdb.conf: [modified]
  mtime.conffile..etc.apport.crashdb.conf: 2019-03-07T14:28:39.455024

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