Nagios Support Forum

Hello,

Since we are currently using Nagios Core, I installed NRPE plugin on all of our Linux servers. It worked fine with Core monitoring host. But it doesn't work with XI monitoring host. I modified the nrpe config file (/usr/local/nagios/etc/nrpe.cfg) and changed the allowed_hosts to the current Xl server IP, but still got the status of "CHECK_NRPE: Error - Could not complete SSL handshake." from monitoring host. How to fix it?

Thank you for your help!

Hong Kang

Hong Kang,

Do you have NRPE running on your remote machines under xinetd? A good indicator that xinetd is in use is if the following file exists: If the above file exists, you will need to add your Nagios XI IP address there instead of in the nrpe.cfg file. You might also try running check_nrpe from Nagios XI using the -n flag to disable SSL:

1. cat /etc/xinetd.d/nrpe
# default: on
# description: NRPE (Nagios Remote Plugin Executor)
service nrpe
{
flags = REUSE
socket_type = stream
port = 5666
wait = no
user = nagios
group = nagios
server = /usr/local/nagios/bin/nrpe
server_args = -c /usr/local/nagios/etc/nrpe.cfg --inetd
log_on_failure += USERID
disable = no
only_from = 127.0.0.1 ipofxi
}

2. ./check_nrpe -H ipofremote -n
CHECK_NRPE: Error receiving data from daemon.

Try it without the -n.

# ./check_nrpe -H ipofremote
CHECK_NRPE: Error - Could not complete SSL handshake.

ipofxi

Are you certain that XI isn't going through NAT or similar? Is there a difference in NRPE version between the two installs of Nagios? Typically this should work with no problems.

On your remote host, please run an 'ldd' against your NRPE binary.

On this box, I installed NRPE plugin (nagios-plugins-2.0.2.tar.gz) which worked fine with Nagios Core monitoring host. After we decided to try Nagios XI, I installed NRPE agent (linux-nrpe-agent.tar.gz) on another box which works with Nagios XI host. I know these are two different files, and the installation steps are also different.

Here is the output for ldd:
# ldd /usr/local/nagios/bin/nrpe
linux-vdso.so.1 => (0x00007fff745f2000)
libssl.so.10 => /usr/lib64/libssl.so.10 (0x00000030a9400000)
libcrypto.so.10 => /usr/lib64/libcrypto.so.10 (0x00000030a6800000)
libnsl.so.1 => /lib64/libnsl.so.1 (0x00000030b2a00000)
libc.so.6 => /lib64/libc.so.6 (0x000000309f800000)
libgssapi_krb5.so.2 => /lib64/libgssapi_krb5.so.2 (0x00000030a9000000)
libkrb5.so.3 => /lib64/libkrb5.so.3 (0x00000030a8800000)
libcom_err.so.2 => /lib64/libcom_err.so.2 (0x00000030a7400000)
libk5crypto.so.3 => /lib64/libk5crypto.so.3 (0x00000030a7c00000)
libdl.so.2 => /lib64/libdl.so.2 (0x00000030a0000000)
libz.so.1 => /lib64/libz.so.1 (0x000000309f400000)
/lib64/ld-linux-x86-64.so.2 (0x000000309f000000)
libkrb5support.so.0 => /lib64/libkrb5support.so.0 (0x00000030a8400000)
libkeyutils.so.1 => /lib64/libkeyutils.so.1 (0x00000030a8000000)
libresolv.so.2 => /lib64/libresolv.so.2 (0x00000030a1400000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x000000309fc00000)
libselinux.so.1 => /lib64/libselinux.so.1 (0x00000030a1000000)

jolson wrote:Hong Kang,

Do you have NRPE running on your remote machines under xinetd? A good indicator that xinetd is in use is if the following file exists:

Code: Select all

cat /etc/xinetd.d/nrpe

If the above file exists, you will need to add your Nagios XI IP address there instead of in the nrpe.cfg file. You might also try running check_nrpe from Nagios XI using the -n flag to disable SSL:

Code: Select all

cd /usr/local/nagios/libexec
./check_nrpe -H <hostname> -n

hkang wrote:1. cat /etc/xinetd.d/nrpe
# default: on
# description: NRPE (Nagios Remote Plugin Executor)
service nrpe
{
flags = REUSE
socket_type = stream
port = 5666
wait = no
user = nagios
group = nagios
server = /usr/local/nagios/bin/nrpe
server_args = -c /usr/local/nagios/etc/nrpe.cfg --inetd
log_on_failure += USERID
disable = no
only_from = 127.0.0.1 ipofxi
}

2. ./check_nrpe -H ipofremote -n
CHECK_NRPE: Error receiving data from daemon.

After making these changes, did you restart the xinetd service on the remote host?
We also have this guide as it address issues similar to yours:

https://assets.nagios.com/downloads/nag ... utions.pdf

After I restarted the xinetd service on the remote client, I got the following from the monitoring website:

/ Disk Usage Unknown 13m 4s 5/5 2016-01-14 09:01:11 CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.

/home Disk Usage Unknown 12m 48s 5/5 2016-01-14 09:01:27 CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.

/tmp Disk Usage Unknown 11m 48s 5/5 2016-01-14 09:02:27 CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.

CPU Stats Unknown 11m 34s 5/5 2016-01-14 09:02:42 CHECK_NRPE: Received 0 bytes from daemon. Check the remote server logs for error messages.

Can I please see the output of this command from the box you are trying to get NRPE working on?