Nrpe

We need two programs: 'nrpe' to be run as daemon or inet service, and 'check_nrpe' to be called by nagios. In general we need 'check_nrpe' on clonweb and 'nrpe' on all other machines.

Clonweb only (where Nagios is running): produce 'check_nrpe' and copy it to 'nagios' area:

 cd /usr/local/src/nrpe-2.6
 ./configure
 make all
 cp src/check_nrpe /www/nagios2.6/libexec
 chown nagios.nagios /www/nagios2.6/libexec/check_nrpe

Generic installation (all machines, including clonweb if it is not done yet):

 cd /usr/local/src
 cp ../downloads/nrpe-2.6.tar.gz .
 gunzip nrpe-2.6.tar.gz
 tar xvf nrpe-2.6.tar
 rm nrpe-2.6.tar
 cd /usr/local/src/nrpe-2.6
 ./configure --prefix=/apps/nrpe2.6 --enable-command-args

Compiling:

 make all

On clonweb (where Nagios is running):

 cp src/check_nrpe /www/nagios2.6/libexec

On any other machine which suppose to be remotely monitored by clonweb:

 mkdir /apps/nrpe2.6
 mkdir /apps/nrpe2.6/libexec
 mkdir /apps/nrpe2.6/etc
 mkdir /apps/nrpe2.6/bin
 cp sample-config/nrpe.cfg /apps/nrpe2.6/etc/
 cp src/nrpe /apps/nrpe2.6/bin
 cp src/check_nrpe /apps/nrpe2.6/libexec/
 cp init-script /etc/init.d/nrpe

 emacs /etc/init.d/nrpe:
 # config: /apps/nrpe2.6/etc/nrpe.cfg
 NrpeBin=/apps/nrpe2.6/bin/nrpe
 NrpeCfg=/apps/nrpe2.6/etc/nrpe.cfg

emacs /apps/nrpe2.6/etc/nrpe.cfg:

 dont_blame_nrpe=1
 command[check_disk_test]=/apps/nrpe2.6/libexec/check_disk -w 20 -c 10 -p /
 command[check_disk]=/apps/nrpe2.6/libexec/check_disk -w $ARG1$ -c $ARG2$ -p $ARG3$

on clonweb: copy plugins we want to execute remotely

(remote machines will not see /www, only /apps !!!) cp /www/nagios2.6/libexec/check_disk /apps/nrpe2.6/libexec/

To test 'check_nrpe' run following commands from another machine where 'check_nrpe' installed. Requests shell be sent to the machine where 'nrpe' is running (in our examples it is clon10):

on clonweb:

 /www/nagios2.6/libexec/check_nrpe -H clon10 -c check_disk_test
     must return something like that:
DISK OK - free space: / 1363 MB (16% inode=74%);| /=7054MB;8483;8493;0;8503

 /www/nagios2.6/libexec/check_nrpe -H clon10 -c check_disk -a 20 20 /
 

on non-clonweb:

 /apps/nrpe2.6/libexec/check_nrpe -H clon10 -c check_disk_test
 /apps/nrpe2.6/libexec/check_nrpe -H clon10 -c check_disk -a 20 20 /

Testing 'nrpe':

NOTE: user 'nagios' and group 'nagios' must exist to run 'nrpe' daemon !!!

To greate group 'nagios' add following line to /etc/group file:

 nagios::9997:nagios

To create user on Solaris:

 useradd -g nagios -d /home/nagios -c "Nagios" nagios'
    (add flag '-m' if want to force home directory creation).

If complains, check passwd file by 'pwconv' (should not be blank lines in the end etc). To add group on Solaris add following line to '/etc/group' file: 'nagios::9997:nagios' (id maybe different of course).

On Linux use '/usr/bin/system-config-users' utility.

To start/stop/restart 'nrpe' daemon on Linux (as 'root'):

 /etc/init.d/nrpe start
 /etc/init.d/nrpe stop
 /etc/init.d/nrpe restart

To start 'nrpe' daemon on Solaris (as 'root'):

 /apps/nrpe2.6/bin/nrpe -c /apps/nrpe2.6/etc/nrpe.cfg -d

 ps -ef | grep nrpe
 nagios  3051     1   0 13:09:24 ?           0:00  ./nrpe -c /apps/nrpe2.6/etc/nrpe.cfg -d

 more /var/run/nrpe.pid
 3051

In both systems it is running under user 'nagios' in according to it's config file.

Normally we are running 'nrpe' not as a daemon but as part of 'inet' service. It was configured by following steps:

Add following line to /etc/services:

 nrpe            5666/tcp        # NRPE

Linux (xinet): create file /etc/xinetd.d/nrpe' with following contents:

 # default: on
 # description: NRPE
 service nrpe
 {
         flags           = REUSE
         socket_type     = stream        
         wait            = no
         user            = nagios
         group           = nagios
         server          = /apps/nrpe2.6/bin/nrpe
         server_args     = -c /apps/nrpe2.6/etc/nrpe.cfg --inetd
         log_on_failure  += USERID
         disable         = no
 ###        only_from       = 129.57.167.42
 }

Solaris (inet): add following line to /etc/inetd.conf:

 nrpe    stream  tcp     nowait  nagios /apps/nrpe2.6/bin/nrpe /apps/nrpe2.6/bin/nrpe -c /apps/nrpe2.6/etc/nrpe.cfg --inetd

Linux: restart xinet service:

 /etc/init.d/xinetd restart

Solaris:

 inetconv -i /etc/inet/inetd.conf
 svcadm restart /network/inetd

Run mentioned above tests from another machine. Check for possible errors:

  tail -100 /var/log/messages | grep nrpe

Solaris:

 svcs | grep nrpe
 online          0:41:40 svc:/network/nrpe/tcp:default

Useful commands:

 netstat -lp
 more /var/log/messages | grep nrpe
     Jan  7 22:28:29 clonpc2 xinetd[986]: execv( /apps/nrpe2.6/bin/ ) failed: Permission denied (errno = 13)