Tag Archives: IPv6

Moving to IPv6

My blog has yet again moved; this time to Frobbit. It being 2014 and all I figured that it was about time that the blog became reachable over IPv6.

Easy IPv4+IPv6 Nagios monitoring using check_v46

Not feeling ready to give up on IPv4 quite yet? In that case you most likely want your Nagios to probe your services on both their IPv4- as well as their IPv6 addresses.

Looking into how how to handle that duplication in a sane manner I stumbled over the rather convenient check_v46 plugin wrapper. Assuming the actual check being run provides the -4/-6 options check_v46 can automatically, based on a hostname lookup, test using IPv4 and/or IPv6, and then return the worst result. See below for a trivial example, as well a matching example response.

define command{
       command_name    dual_check_http
       command_line    /usr/local/nagios/check_v46 -H '$HOSTNAME$' /usr/lib/nagios/plugins/check_http
CRITICAL: IPv6/halleck.arrakis.se OK, IPv4/halleck.arrakis.se CRITICAL

Do note that there is also the option of manually feeding check_v46 IPv4 and IPv6 addresses. See the plugin –help for the actual details. Also note that the check_v46 wrapper does not appear to work with the Nagios embedded Perl.

Of course, a more perfect solution probably requires Nagios itself to be more IPv4 vs IPv6 aware. For example, in the case that a host (or a datacenter) temporarily becomes unavailable over IPv6, it might then be more helpful if the service checks focused primarily on the IPv4 results, instead of either going full ballistic or completely silent. Yet, as long as good enough is good enough, the check_v46 wrapper is definitely an easy win.


For some reason I decided it was a good idea to register the domain coloncolonone.net. Currently it is only used to serve a static html page, proclaiming the following message.

There’s no place like ::1

Any ideas on other, possible slightly more creative, ways to use the domain name?

Going IPv6

As of now you can visit this web site using IPv6. This thanks to a tunnel provided to me by SixXS. Please report any problems you might experience.

Well, at least you can kind of visit this site using IPv6. You still need an IPv4 connection to look up the domain name. Providing IPv6 DNS response will probably have to wait until I get native IPv6, which according to the post IPv6 for Gandi (coming soon!) might not be that far into the future.

UPDATE: Now using a Gandi (beta) IPv6 address.