ping: sendto: No buffer space available with DU DNSes

Today I faced I pretty weird issue, having no internet connection since last night.

Chrome is telling me that the DNS lookup fails, and since I know, here in UAE, problems with DU DNSes are pretty frequent, I thought I just needed to use different DNS servers.

Unfortunately, openDNS wasnt solving my issues, and when I tried with the infamous Google Public DNS ( 8.8.8.8 and 8.8.4.4 ) without any good feedback, I thought it could be something out of my jurisdiction :)

Pissed off, I tried to ping the DNS servers manually:

1
2
3
4

ping 8.8.8.8
PING 8.8.8.8 (8.8.8.8): 56 data bytes
ping: sendto: No buffer space available
ping: sendto: No buffer space available

So now things are interesting: the No buffer space available tells me that there is something seriously weird going on today – never seen before.

With a quick search I’m able to fix the problem: seems that I need to shutdown the interface itself.

First, I needed to retrieve the interface used:

1
2
3
4
5
6
7
8
9

sudo route -n get 8.8.8.8

   route to: 8.8.8.8
destination: 8.8.8.8
    gateway: 10.168.10.221
  interface: tun0
      flags: <UP,GATEWAY,HOST,DONE,WASCLONED,IFSCOPE,IFREF>
 recvpipe  sendpipe  ssthresh  rtt,msec    rttvar  hopcount      mtu     expire
       0         0         0         0         0         0      1500         0

then it’s a simple matter of:

1
2

sudo ifconfig tun0 down
sudo ifconfig tun0 up

DNS working as expected and the connection is back.