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 create user on Solaris: 'useradd -d /home/nagios -m -c "Nagios" nagios' (-m will 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)