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This article was written for version 6.2 of Monitor, it could work on both lower and higher version if nothing else is stated.
This how-to will describe how to configure a poller that is located behind a NAT firewall where port forwarding is not possible. This is called running a passive poller. Running multiple poller nodes behind the very same NAT is not supported ? two nodes must not be seen at the same IP address, in the master's point of view.
In this example we have a master server called master01 and a poller called nat_poller that is behind a firewall.
- The master server must be accessible on port 22 and 15551 from the poller.
- Basic understanding of op5 Monitor with master-peer configuration
Important information in case of peered masters
If you have more than one master in your environment, the steps below that relates to "master01" also need to be performed on the peered master. You also need to "mon node add" the peered master.
On master01, edit the /etc/hosts file using your favorite text editor, and map the hostname nat_poller to the outgoing NAT IP address of nat_poller (i.e. the IP address which the poller will connect from in the master's point of view). Example:
On master01, set up the poller node nat_poller by executing the command below.
On master01, edit the /opt/monitor/op5/merlin/merlin.conf configuration file, and insert takeover = no and connect = no into the nat_poller configuration block. Example:
On nat_poller, set up the master node master01 by executing the command below.
On nat_poller, edit the /opt/monitor/op5/merlin/merlin.conf configuration file, and insert into the master01 configuration block: a sub-block called object_config, containing fetch_name and fetch settings. Example:
The value of the fetch_name setting should be set to the name of the poller.
On nat_poller, disable any default nagios object configuration files by executing the command below.
On nat_poller, verify and set up SSH connectivity by executing the command below.
On master01, restart the op5 Monitor system services by executing the command below.
On nat_poller, fetch the new configuration from master01 by executing the command below.