Nagios Support Forum

I have this problem with NRPE. I'm trying to run check_oracle_health (https://labs.consol.de/nagios/check_oracle_health/) plugin through NRPE.
When i exicute the script it works:
/usr/local/nagios/libexec/check_oracle_health -t 240 --connect=DEV --user=nagios --password='xxxxxxxx' --mode=connected-users --warning 30 --critical 50 --method sqlplus
OK - 1 connected users | connected_users=1;30;50
but when I'm trying to run it through NRPE i got this error:
/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c test
NRPE: Unable to read output

nrpe.cfg

log_facility=daemon
debug=0
pid_file=/usr/local/nagios/var/nrpe.pid
server_port=5666
nrpe_user=nagios
nrpe_group=nagios
dont_blame_nrpe=1
allow_bash_command_substitution=0
command_timeout=60
connection_timeout=300
command[check_users]=/usr/local/nagios/libexec/check_users -w 5 -c 10
command[check_load]=/usr/local/nagios/libexec/check_load -w 3.5 -c 4
command[check_hda1]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /dev/hda1
command[check_data]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /mnt/data
command[check_root]=/usr/local/nagios/libexec/check_disk -w 20% -c 10% -p /
command[check_zombie_procs]=/usr/local/nagios/libexec/check_procs -w 5 -c 10 -s Z
command[check_total_procs]=/usr/local/nagios/libexec/check_procs -w 500 -c 550
command[check_swap]=/usr/local/nagios/libexec/check_swap -w 20% -c 10%
command[test]=sudo /usr/local/nagios/libexec/check_oracle_health -t 240 --connect=DEV --user=nagios --password='xxxxxxxx' --mode=connected-users --warning 30 --critical 50 --method sqlplus

i tried with /bin/sudo /usr/local/nagios/libexec/check_oracle_health -t 240 --connect=DEV --user=nagios --password='xxxxxxxx' --mode=connected-users --warning 30 --critical 50 --method sqlplus
and it still doesn't work.

Without sudo permission, it still doesn't work through NRPE

/etc/sudoers
nagios ALL=(ALL) NOPASSWD: ALL

getsebool -a | grep nagios
logging_syslogd_run_nagios_plugins --> on
nagios_run_pnp4nagios --> off
nagios_run_sudo --> on
nagios_use_nfs --> on

I edited check_oracle_health plugin adding these lines in the begin to always use specific environment:
$ENV{'ORACLE_HOME'}="/usr/lib/oracle/11.2/client64";
$ENV{'LD_LIBRARY_PATH'}="/usr/lib/oracle/11.2/client64/lib:/lib:/usr/lib";
$ENV{'TNS_ADMIN'}="/usr/lib/oracle/11.2/client64/network/admin";

Installed packages:
oracle-instantclient11.2-basic-11.2.0.4.0-1.x86_64.rpm
oracle-instantclient11.2-devel-11.2.0.4.0-1.x86_64.rpm
oracle-instantclient11.2-sqlplus-11.2.0.4.0-1.x86_64.rpm

ps -ef | grep nrpe
nagios 27100 1 0 09:23 ? 00:00:00 /usr/local/nagios/bin/nrpe -c /usr/local/nagios/etc/nrpe.cfg -f

/usr/local/nagios/libexec/check_nrpe --version
NRPE Plugin for Nagios
Version: 3.2.1

It works with other checks:
/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c check_root
DISK OK - free space: / 15 GB (39.57% inode=96%);| /=23GB;30;34;0;38

With debug option set to 1 i got this log in /var/log/messages
Apr 24 10:16:35 app_server nrpe[28584]: CONN_CHECK_PEER: checking if host is allowed: 127.0.0.1 port 36042
Apr 24 10:16:35 app_server nrpe[28585]: WARNING: my_system() seteuid(0): Operation not permitted
Apr 24 10:16:35 app_server systemd: Created slice User Slice of root.
Apr 24 10:16:35 app_server systemd: Started Session c27 of user root.
Apr 24 10:16:36 app_server systemd: Removed slice User Slice of root.

Nrpe is installed from the Source. I used --enable-command-args with the installation

Thank you in advance.
Milos

What's the test command?

/usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c test
NRPE: Unable to read output

I think that unable to read output means there was no output.
A command is one defined in nrpe.cfg or the nrpe include dir if defined.

Thanks @gormank helping out on the Community Forum.

When you're running the plugin locally and it works. Are you logged in as root or the nagios user? Pretty sure this is a permissions or sudoers issue.

We have a helpful troubleshooting guide for this error message on our KB. Please follow the steps and let me know if are able to get it going.

NRPE - NRPE: Unable To Read Output

Hi guys,

I will try to describe better:

Nagios
nrpe
|
|
V
app_server -------------------------> db_server
check_oracle_health

I am trying to test the oracle connection between app_server and db_server via the check_oracle_health plugin written in Perl form Nagios via NRPE.
I installed everything that is needed on app_server to use the check_oracle_health plugin and to test db_server health.
From app_server I CAN get the output. And everything is working correctly.
The command is defined in nagios.cfg on app_server:
command[test]=sudo /usr/local/nagios/libexec/check_oracle_health -t 240 --connect=DEV --user=nagios --password='xxxxxxxx' --mode=connected-users --warning 30 --critical 50 --method sqlplus
I tried as root and as nagios user. I get the same output.
I also added the ENV variables directly in the script:
$ENV{'ORACLE_HOME'}="/usr/lib/oracle/11.2/client64";
$ENV{'LD_LIBRARY_PATH'}="/usr/lib/oracle/11.2/client64/lib:/lib:/usr/lib";
$ENV{'TNS_ADMIN'}="/usr/lib/oracle/11.2/client64//network/admin";

@benjaminsmith I tried everything from that article but I had no luck.

Thanks!

Hi,

Which version of NRPE agent is installed on the remote server.?

I'm having same issue with NRPE v4.0.3. I have submitted similar issue today. I'll be testing with NRPE 3.2.1 now.

Thanks,
Srikanth

HI Benjimin Smith,

I having same problem. I'm testing the scripts from this article https://github.com/colebrooke/kubernetes-nagios

I tried two versions of NRPE agent 3.2.1 & 4.0.3 too. Same problem for both versions.

Any one can help us find the root cause ..

Thanks,
Srikanth

Do the base nrpe command work from the nagios server to the remote NRPE server? Please send the output of these commands:
Are you seeing any errors in /var/log/messages or /var/log/secure on the remote NRPE system?

Try changing your command to this:
Then restart NRPE, run this again, and send us the full output:

@ssax this is the output:
[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server
NRPE v3.2.1

[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server -n
CHECK_NRPE: Receive header underflow - only -1 bytes received (4 expected).

[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server -2
NRPE v3.2.1

Output in /var/log/messages on the app_server:
Error: (!log_opts) Could not complete SSL handshake with public_ip: 1
May 14 12:54:11 app_server sshd[6430]: Connection closed by public_ip port 60270 [preauth]

I already changed command on my app_server to:
command[test]=sudo /usr/local/nagios/libexec/check_oracle_health -t 240 --connect=DEV --user=nagios --password='xxxxxxxx' --mode=connected-users --warning 30 --critical 50 --method sqlplus 2>&1
but this didnt help

From Nagios:
[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server -c test
NRPE: Unable to read output

From app_server:
$ /usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c test
NRPE: Unable to read output

I'm using the same versions of NRPE on every server. (NRPE v3.2.1)

Thanks

I'm having the same problem, but my usecase is little different,. I have opened a support request here: https://support.nagios.com/forum/viewto ... =7&t=58573

Let me know if anyone needs more information.

Thanks,
Srikanth

saracm wrote:@ssax this is the output:
[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server
NRPE v3.2.1

[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server -n
CHECK_NRPE: Receive header underflow - only -1 bytes received (4 expected).

[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H app_server -2
NRPE v3.2.1

Output in /var/log/messages on the app_server:
Error: (!log_opts) Could not complete SSL handshake with public_ip: 1
May 14 12:54:11 app_server sshd[6430]: Connection closed by public_ip port 60270 [preauth]

I already changed command on my app_server to:
command[test]=sudo /usr/local/nagios/libexec/check_oracle_health -t 240 --connect=DEV --user=nagios --password='xxxxxxxx' --mode=connected-users --warning 30 --critical 50 --method sqlplus 2>&1
but this didnt help

From Nagios:
[root@nagios ~]# /usr/local/nagios/libexec/check_nrpe -H uq-dev-app -c test
NRPE: Unable to read output

From app_server:
$ /usr/local/nagios/libexec/check_nrpe -H 127.0.0.1 -c test
NRPE: Unable to read output

I'm using the same versions of NRPE on every server. (NRPE v3.2.1)

Thanks