Nagios Support Forum

Nagios XI running 5.8.2
CentOS Linux release 7.5.1804 (Core)
CHECK_NRPE plug 4.0.3

After upgrading our Nagios XI server to 5.8.2 our check_nrpe stopped working.

We receive: CHECK_NRPE: Error - Could not connect to 192.168.8.62. Check system logs on xxx.xxx.xxx.xxx

/var/log/messages shows:
Mar 17 16:57:05 nagiosxii check_nrpe: Error: (nerrs = 0)(!log_opts) Could not complete SSL handshake with 192.168.8.62: rc=0 SSL-error=5

I followed the instructions on downloading and installing check_nrpe again and when I perform the systemctl enable nrpe.service, no error is returned. When I look at the running service on my Nagios XI server using systemctl -a, I search for nrpe and it shows:
nrpe.services loaded failed failed Nagions Remote Plugin Executor

I can see the check_nrpe version by executing:
cd /usr/local/nagions/libexec
./check_nrpe -V

So at this point, I don't believe I'm even able to get check_nrpe working on the Nagios XI server. I edited the nrpe.cfg file to add our Nagios XI's IP address and I set the dont_blame_nrpe=1 and restarted the service - still fails to connect. Tests to other IP addresses show Connection refused.

Any suggestions for resolution?

I also see in the systemctl -a display:

nrpe.socket not-found inactive dead nrpe.socket

Here the output from our /usr/local/nagios/var/nrpe.log. I currently don't have any iptables entries for port 5666. Looks like it's adding our Nagios XI server IP correctly (192.168.8.112):

[1616032983] parse_allowed_hosts: parsing the allowed host string >127.0.0.1,::1,192.168.8.112< to add to ACL list
[1616032983] parse_allowed_hosts: ADDING this record (127.0.0.1) to ACL list!
[1616032983] add_ipv4_to_acl: checking ip-address >127.0.0.1<
[1616032983] add_ipv4_to_acl: ip-address >127.0.0.1< correct, adding.
[1616032983] parse_allowed_hosts: Record added to ACL list!
[1616032983] parse_allowed_hosts: ADDING this record (::1) to ACL list!
[1616032983] parse_allowed_hosts: Record added to ACL list!
[1616032983] parse_allowed_hosts: ADDING this record (192.168.8.112) to ACL list!
[1616032983] add_ipv4_to_acl: checking ip-address >192.168.8.112<
[1616032983] add_ipv4_to_acl: ip-address >192.168.8.112< correct, adding.
[1616032983] parse_allowed_hosts: Record added to ACL list!
[1616032983] Showing ACL lists for both IP and DOMAIN acl's:
[1616032983] IP ACL: 127.0.0.1/32 16777343
[1616032983] IP ACL: 0.0.0.0/20 0
[1616032983] IP ACL: 192.168.8.112/32 1879615680
[1616032983] Added command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10
[1616032983] Added command[check_load]=/usr/local/nagios/libexec/check_load -r -w .15,.10,.05 -c .30,.25,.20
[1616032983] Added command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/hda1
[1616032983] Added command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w 5 -c 10 -s Z
[1616032983] Added command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 150 -c 200
[1616032983] INFO: SSL/TLS initialized. All network traffic will be encrypted.
[1616032983] Starting up daemon
[1616032983] SETUP_WAIT_CONN FOR: IPv4 address: 0.0.0.0 ((null))
[1616032983] Bind to port 5666 on 0.0.0.0 failed: Address already in use.
[1616032983] SETUP_WAIT_CONN FOR: IPv4 address: :: ((null))
[1616032983] Bind to port 5666 on :: failed: Address already in use.
[1616032983] Cannot bind to any address.
/

RESOLVED!

I checked other clients (Windows) from the Nagios XI console and they were returning correct data from check_nrpe calls, so I took the nsclient.ini file from one of the "good" clients and copied it the one I was having issues connecting to. I then restarted the NSClient++ Monitoring Agent" service on the "bad" client and all check_nrpe calls are working again! Not sure what the issue was with that client, but apparently the Nagios XI upgrade to 5.8.2 was unrelated.

Moderators, please feel free to close this post.

Glad to hear you resolved it! Locking thread.

If you have any additional issues, feel free to make a new thread.