Nagios check UDP plugin is a useful tool to check whether UDP ports are open, Read to find out how to use this plugin. 

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How to use Nagios check UDP plugin

check_udp is a plugin that tests UDP connections with a specific host. In other words, it checks whether UDP ports are open.

According to our Support Team, the check UDP plugin is a simple shell script. It relies on nmap utility to test if a remote host is listening on a UDP port. Furthermore, Nagios check UDP plugin also returns the name of the service that should be listening on that port.

check_udp_port: -H remote_host -p port -s service_name

• -H: IP or Name of the remote host
• -p: UDP port number to check
• -s: Name of the service listening on the port

Additionally, this plugin is compatible with Nagios 3.x, Nagios 4.x, and NagiosXI.

However, there is a slight change in the NagiosXI command definition. Since the nmap utility requires root permission to scan the port, we have to add the following to the /etc/sudoers for Nagios check UDP to work smoothly.

NAGIOSXI ALL = NOPASSWD:/usr/local/nagios/libexec/check_udp_port *

Furthermore, the command definition will be:

sudo $USER1$/check_udp_port -H $HOSTNAME$ -p $ARG1$ -s $ARG2$

While using the plugin, we have to send a string to the system we are checking. The system then responds to the command. After that, the plugin verifies the response.

For instance, if there is a server we sent “Test” and it responds with “AllClear”, the command would like:

./check_udp -H xxx.xxx.xxx.xxx -p 5141 -s Test -e  AllClear

Here are a few of the options available for the check udp plugin:

• -h, –help: Prints in-depth help screen
• -V, –version: Prints version information
• –extra-opts=[section][@file]: Reads options from an ini file
• -4, –use-ipv4: Use IPv4 connection
• -6, –use-ipv6: Use IPv6 connection
• -s, –send=STRING: The string to send to the server
• -q, –quit=STRING: The string to send server to start a clean close of the connection

If you would like help configuring the Nagios check UDP plugin, our Support Techs are at your service

[Need assistance with another query? We are available 24/7.]

Conclusion

In brief, our skilled Support Engineers at Bobcares took us through the Nagios check UDP.