* TCP and UDP (Generic)

check_udp_port

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Description:

Simple shell script that uses nmap utility to check if a remote host is listening on a UDP port and what that service is

Current Version

1.1

Last Release Date

2014-06-09

Compatible With

  • Nagios 3.x
  • Nagios 4.x
  • Nagios XI

Owner

Aaron Eidt

License

GPL

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Project Files
FileDescription
check_udp_port

The script

Project Notes
Simple shell script that uses nmap utility to check if a remote host is listening on a UDP port and what that service is. Usage: check_udp_port: -H remote_host -p port -s service_name -H Name or IP of remote host -p UDP port number to check -s Name of the service that should be listening on the port Critical: if service is 'unknown' or state is not open Warning: if service name expected does not match service name listening on the port OK: if the port is open and service name expected matches service name listening. NOTE for NagiosXI command definition: nmap requires root perms to scan the port. Add the following to /etc/sudoers: NAGIOSXI ALL = NOPASSWD:/usr/local/nagios/libexec/check_udp_port * And the command definition should be: sudo $USER1$/check_udp_port -H $HOSTNAME$ -p $ARG1$ -s $ARG2$ UPDATES: ----------------------------- v1.1: made change to egrep statement to include 0-9_- in service names
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fix f_result
by rkutsch, May 31, 2021
#result=`sudo /usr/bin/nmap -sU -p $port -P0 $host`
result=`sudo /usr/bin/nmap -sU -p $port -P0 $host| grep ^${port}/.*`
f_result=`echo $result Nmap done`
p_result=`echo $f_result | awk '{print $1" "$2" "$3}'`
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Stopped working
by Doubravka, August 31, 2019
Good plugin, been using for a while.
Today I upgraded Debian from 9.9 to 10 and this plugin stopped working.
The problem is probably in grep change
line 50:
f_result=`echo $result | egrep -o "${port}/udp [a-zA-Z0-9_-| ]+Nmap done"`

plugin output:
grep: Invalid range end
CRITICAL:

Does anyone know how to fix this issue?
I am no expert at regex

Thanks
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Permissions and return state
by leire, May 31, 2019
Hello,
I have to give permissions to execute all the users the nmap command
chmod u+s /usr/bin/nmap

And I change exit value at the end, to UNKNOWN state because is confused CRITICAL state.

echo "UNKNOWN: $p_result ------"
exit ${STATE_UNKNOWN}
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tip for openvpn
by andy232, August 31, 2016
I changed the following line to avoid problems with services containing "open" in the name, e.g.: openvpn

if [ `echo $f_result | egrep -c 'udp open'` -gt 0 ]; then
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Eliminate MAC-statement
by crefeld, April 30, 2015
Thanks for this helpful tool.
For some nmap-versions (e.g. nmap 5.21 on opensuse 11.4) you will have to remove an extra line with the MAC-address after the port line to get a valid result string:

PORT STATE SERVICE
177/udp open xdmcp
MAC Address: 00:30:48:11:22:33 (Supermicro Computer)

Nmap done: 1 IP address (1 host up) scanned in 0.09 seconds



As not being familiar with extended regular expressions I extended the nmap statement:

result=`/usr/bin/nmap -sU -p $port -P0 $host |grep -v MAC`

This works but feel free to find the respective expression for f_result.
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Nice, but one bug
by willamowius, December 31, 2014
I had to escape the dash in the egrep pattern (using GNU egrep 2.14), but after that it worked great!

f_result=`echo $result | egrep -o "${port}/udp [a-zA-Z0-9_-| ]+Nmap done"`
1 of 1 found this review helpful.
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