Check_MK is now providing native support for monitoring IPv6 and even dual-stack hosts.
This has been implemented in a clean and straight forward way. For each host you can choose which address family shal be used for communication with this host. By default Check_MK is still using only IPv4, but now you can change it to IPv6 for monitoring IPv6 only hosts. In WATO this is done by configuring the host attribute IP Address Family.
You can even configure one host to be monitored via IPv4 and IPv6 at the same time. In this situation you need to decide which of the both address families is the primary one. The primary address family is the one which is used for regular monitoring tasks (communication with the agent or SNMP). The secondary address family is only being pinged by default. For the secondary address family a dedicated PING service named (PING v4 or PING v6) is added to the dual-stack hosts. By default the primary address family is IPv4 for all dual-stack hosts. In WATO this can be changed by configuring the rule set Primary IP address family of dual-stack hosts.
In some cases you want to perform active checks to check the avilability of a service, e.g. HTTP, using both IPv4 and IPv6. For this case you can add two active checks to the dual-stack host, one having IPv6 enabled and one without having it enabled for using IPv4. But each active check needs to support IPv6 on its own. For the moment the only check working vith IPv6 is check_http.
This is the default and recommended way for monitoring dual-stack hosts. You use one address family for monitoring the whole system and the other one is just being pinged.
Note: If you use the Check_MK Enterprise Edition together with the Micro Core, the Smart PING mechanism is not used for IPv6 hosts at the moment. This mechanism has a slightly slower performance, but if you don't have too many IPv6 hosts, this should be OK for the beginning.
If you use the xinetd for serving the Check_MK agent output, you need to configure xinetd to create an IPv6 socket. By default it only creates an IPv4 socket. If you use the Agent Bakery, the baked agents configure xinetd to use the primary IP address family of the hosts.
The basic implementation for IPv6 monitoring has been done. But there are several components in the Check_MK environment left which need to be extended to be fully compatible with IPv6. Some of them are: