Sunday, July 13, 2014

Testing IPv6-only on Ubuntu

A nice try, just for fun: how is the Internet behaving with IPv6-only on a Ubuntu system?

Before we start: I think IPv4 will be in use for at least 10 years, together with IPv6. So IPv6-only is just a test.

Pre-condition: your IPv6 must be working. Check with

ping6 -c4

Two steps to remove IPv4:

sudo gedit /etc/resolv.conf
and put this before the existing nameserver entry:

nameserver 2001:4860:4860::8888
nameserver 2001:4860:4860::8844

Then remove your IPv4 address, in my case from wlan0:

sudo ip addr del dev wlan0

You now only have IPv6. (Don't worry: after a network reload, you have your IPv4 back)

Check that IPv4 is not working anymore:

$ ping
connect: Network is unreachable

Check that IPv6 is still working:

ping6 -c4

With your webbrowser, visit (which should all work):

Not working (shame on them!):

You can visit an IPv4-only site like via . Note that this only work for plain HTTP, not for HTTPS.

If you run

sudo apt-get update && sudo apt-get upgrade

you will get messages like:

Could not resolve ''
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?


Back to dual stack IPv4 and IPv6? Just reload your network.

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