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On Ubuntu 16.04 I have Network Manager configured to automatically use an OpenVPN connection at system start-up. This works well.

However, when the machine resumes after being suspended, although the VPN reconnects, I am unable to browse (or ping) websites because host names cannot be resolved. For some reason DNS look-ups are failing.

ping: unknown host www.google.com

This only started happening a couple of weeks ago, I'm not sure what has changed.


Output of cat /etc/NetworkManager/NetworkManager.conf:

[main]
plugins=ifupdown,keyfile,ofono
dns=dnsmasq

[ifupdown]
managed=false

Output of 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
nameserver 127.0.1.1

Output of host -v www.apple.com (before suspending):

Trying "www.apple.com"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41111
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 9, ADDITIONAL: 7

;; QUESTION SECTION:
;www.apple.com.         IN  A

;; ANSWER SECTION:
www.apple.com.      1287    IN  CNAME   www.apple.com.edgekey.net.
www.apple.com.edgekey.net. 1516 IN  CNAME   www.apple.com.edgekey.net.globalredir.akadns.net.
www.apple.com.edgekey.net.globalredir.akadns.net. 1516 IN CNAME e6858.dsce9.akamaiedge.net.
e6858.dsce9.akamaiedge.net. 20  IN  A   104.94.190.92

;; AUTHORITY SECTION:
dsce9.akamaiedge.net.   1516    IN  NS  n3dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n1dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n6dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  a0dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n4dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n5dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n0dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n7dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n2dsce9.akamaiedge.net.

;; ADDITIONAL SECTION:
a0dsce9.akamaiedge.net. 1516    IN  AAAA    2600:1480:e800::c0
n0dsce9.akamaiedge.net. 1516    IN  A   88.221.81.194
n1dsce9.akamaiedge.net. 1516    IN  A   23.62.100.157
n2dsce9.akamaiedge.net. 1516    IN  A   95.101.2.121
n3dsce9.akamaiedge.net. 1516    IN  A   95.101.79.79
n4dsce9.akamaiedge.net. 1516    IN  A   23.62.100.159
n5dsce9.akamaiedge.net. 1516    IN  A   23.62.100.164

Received 504 bytes from 127.0.1.1#53 in 66 ms
Trying "e6858.dsce9.akamaiedge.net"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60195
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 9, ADDITIONAL: 9

;; QUESTION SECTION:
;e6858.dsce9.akamaiedge.net.    IN  AAAA

;; ANSWER SECTION:
e6858.dsce9.akamaiedge.net. 20  IN  AAAA    2a02:26f0:60:186::1aca
e6858.dsce9.akamaiedge.net. 20  IN  AAAA    2a02:26f0:60:199::1aca

;; AUTHORITY SECTION:
dsce9.akamaiedge.net.   1516    IN  NS  n0dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n2dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n3dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  a0dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n4dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n1dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n5dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n6dsce9.akamaiedge.net.
dsce9.akamaiedge.net.   1516    IN  NS  n7dsce9.akamaiedge.net.

;; ADDITIONAL SECTION:
a0dsce9.akamaiedge.net. 1516    IN  AAAA    2600:1480:e800::c0
n0dsce9.akamaiedge.net. 1516    IN  A   88.221.81.194
n1dsce9.akamaiedge.net. 1516    IN  A   23.62.100.157
n2dsce9.akamaiedge.net. 1516    IN  A   95.101.2.121
n3dsce9.akamaiedge.net. 1516    IN  A   95.101.79.79
n4dsce9.akamaiedge.net. 1516    IN  A   23.62.100.159
n5dsce9.akamaiedge.net. 1516    IN  A   23.62.100.164
n6dsce9.akamaiedge.net. 1516    IN  A   23.62.100.165
n7dsce9.akamaiedge.net. 1516    IN  A   23.62.100.166

Received 454 bytes from 127.0.1.1#53 in 29 ms
Trying "e6858.dsce9.akamaiedge.net"
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44627
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;e6858.dsce9.akamaiedge.net.    IN  MX

;; AUTHORITY SECTION:
dsce9.akamaiedge.net.   600 IN  SOA n0dsce9.akamaiedge.net. hostmaster.akamai.com. 1489520008 1000 1000 1000 1800

Received 109 bytes from 127.0.1.1#53 in 28 ms

Output of host -v www.apple.com (after suspending):

Trying "www.apple.com"
;; connection timed out; no servers could be reached
  • Edit your question to include the terminal output of cat /etc/NetworkManager/NetworkManager.conf and cat /etc/resolv.conf and host -v www.apple.com. Show me the last command from before AND after suspend. – heynnema Mar 13 '17 at 21:59
  • ps: does DNS continue to work after suspend if you DON'T use OpenVPN? – heynnema Mar 13 '17 at 22:06
  • thanks heynnema, yes, DNS continues to work after suspending when not using OpenVPN – freddybob Mar 14 '17 at 20:01
  • What happens if you restart dnsmasq after a suspend? Does it work then? – heynnema Mar 14 '17 at 20:34
  • I couldn't work out how to restart dnsmasq but I found restarting network-manager would fix the problem sometimes but not every time. So I read through a few bug reports regarding network-manager, DNS and suspend. One commenter suggested downgrading the network-manager package with sudo apt install network-manager=1.2.2-0ubuntu0.16.04.4 and sudo apt-mark hold network-manager so I've tried that as a workaround and so far so good. – freddybob Mar 14 '17 at 22:06
0

On Tuesday (2017-04-18) my system updates included new versions of several DNS-related packages (including dnsutils and dnsmasq-base). Once these were installed the problem went away.

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