Install

 mkdir -p /usr/lib/nagios/plugins/
 wget https://raw.githubusercontent.com/arheops/asterisk_nrpe_checks/master/check_astchannels.py \
    -O /usr/lib/nagios/plugins/check_astchannels.py
 chmod a+x /usr/lib/nagios/plugins/check_astchannels.py
 /usr/lib/nagios/plugins/check_astchannels.py -C install

For vicidial only, for your OS check nrpe config file location

 echo 'command[check_asterisk_channels]=/usr/lib/nagios/plugins/check_astchannels.py -c 1000 -w 100 -C channels' \
   >>/etc/nrpe.cfg
 systemctl restart nrpe

Test at nagios server:

 /usr/lib64/nagios/plugins/check_centreon_nrpe3 -H <IP_HERE> -c check_asterisk_channels