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.


Hi there! I recently wrote an ebook on web application security, currently sold on leanpub, the Amazon Kindle store and gumroad.

It contains 160+ pages of content dedicated to securing web applications and improving your security awareness when building web apps, with chapters ranging from explaining how to secure HTTP cookies with the right flags to understanding why it is important to consider joining a bug bounty program.

Feel free to skim through some of the free chapters published on this blog and, if the content seems interesting enough to you, grab a copy on leanpub, the Amazon Kindle store, gumroad or simply checkout right down below!

Buy the Web Application Security ebook for $9.99

In the mood for some more reading?

...or check the archives.