Nagios plugin check_sys 1.4

Purpose:

• disk space
• process list
• swap utilization
• load (run queue)
• syslog
• errpt (AIX)

Advantages:

• Written in C (for speed and portability)
• Configuration can be completely delegated to the servers administrators (which do not need to have access to the Nagios server)
• Fewer service checks and significantly less configuration overhead
• Currently runs under Linux, Solaris, Tru64, AIX and *BSD

Installation:

1. Edit file config.h:

   • Modify parameter of statement #define SYSTEM to match your OS (LINUX, SOLARIS, TRU64, AIX or BSD)

   • For operating systems which do not support function snprintf:
        Uncomment line: #define USE_SNPRINTF

   • To disable disk space checks:
        Comment line: #define CHECK_DISK

   • To disable process table checks:
        Comment line: #define CHECK_PROC

   • To disable swap (paging space) utilization checks:
        Comment line: #define CHECK_MEM

   • To disable load (run queue) checks:
        Comment line: #define CHECK_LOAD

   • To disable syslog checks:
        Comment line: #define CHECK_SYSLOG

   • To disable errpt checks: (AIX only)
        Comment line: #define CHECK_ERRPT

2. Compile file check_sys.c:
      cc -O2 -o check_sys check_sys.c
      strip check_sys

3. Login as root
      su -

4. Create group nagios and user nagios

5. Install executable file and example files to /usr/local/nagios and prepare directory /var/local/nagios:
      ./install.sh

6. AIX only: Prepare swap (paging space) utilization checks:
      cp -p /usr/bin/svmon /usr/local/nagios/libexec
      chown root /usr/local/nagios/libexec/svmon
      chmod 4750 /usr/local/nagios/libexec/svmon

Configuration:

/usr/local/nagios/etc/proctab:

This configuration file defines the checks of the process table and contains 5 fields separated by white space(s):

1. Name of the process
2. Critical minimum number of processes
3. Warning minimum number of processes
4. Warning maximal number of processes
5. Critical maximal number of processes

/usr/local/nagios/etc/disctab:

This configuration file defines the checks of the amount of free disk space (mount points) and contains 3 fields separated by white space(s):

1. Mountpoint
2. Critical minimum amount of free space (in kB)
3. Warning minimum amount of free space (in kB)

/usr/local/nagios/etc/romtab:

This configuration file lists all mount points which are allowed to be 100% full without triggering a critical alert. Usually this are mount points for CD-ROM drives.

/usr/local/nagios/etc/errpttab: (AIX only)

This configuration file defines the alert type (OK, WARNING, CRITICAL) which should be triggered by a certain type of errpt entry (by LABEL). By default every errpt entry which belongs to the classes H, O or U triggers a critical alert, while the remaining entries trigger warning alerts. The configuration file contains 2 fields separated by white space(s):

1. Label
2. Alert type

/usr/local/nagios/etc/loadrc:

This configuration file defines the critical (C_LOAD) and warning (W_LOAD) thresholds of the system load (run queue). C_LOAD and W_LOAD define 3 values separated by a comma: mean value of the last 5 minutes, mean value of the last 10 minutes and mean value of the last 15 minutes.

/usr/local/nagios/etc/memrc:

This configuration file defines the critical (C_SWAP) and warning (W_SWAP) thresholds of the amount of free swap (paging file) space in kB.

Syslog configuration:

/etc/syslog.conf: (syslog)

*.err                            /var/local/nagios/critical.log
*.notice;*.!err;kern.none        /var/local/nagios/warning.log

/etc/syslog-ng/syslog-ng.conf: (syslog-ng)

filter f_nagios_critical { level(err, crit, alert, emerg); };
filter f_nagios_warning { level(notice, warning) and not facility(kern) and not match("STATS: dropped"); };

destination nagios_critical { file("/var/local/nagios/critical.log" owner(nagios) group(nagios) perm(0644)); };
destination nagios_warning { file("/var/local/nagios/warning.log"  owner(nagios) group(nagios) perm(0644)); };

log { source(src); filter(f_nagios_critical); destination(nagios_critical); };
log { source(src); filter(f_nagios_warning); destination(nagios_warning); };

Nagios configuration:

A possible service configuration:

define command {
    command_name            check-nrpe-u
    command_line            /usr/local/nagios/libexec/check_nrpe -n -H $HOSTADDRESS$ -u -c $ARG1$	
}

define service {
    host_name               event_template
    name                    event_template
    max_check_attempts      1
    notification_interval   0
    notification_options    c
    stalking_options        c
    register                0
    use                     dummy_template
}

define service {
    host_name               intranet
    service_description     check-sys
    check_command           check-nrpe-u!check_sys
    contact_groups          intranet-admins
    use                     event_template
}

• max_check_attempts should be set to 1 (otherwise you will miss error log events)
• stalking_options may be set to "c" or "c, w" to ensure that all error log events end up in Nagios's event log
• Option "-u" is recommended for check_nrpe: this ensures that you will not be notified for short network outages (max_check_attempts is set to 1). Use another service check (check_ping) with a larger max_check_attempts value to detect a host failure

Changelog

Changes since version 1.4:

• Tru64 is now supported
• Errpt check is now configurable by configuration file errpttab

Changes since version 1.3:

• Solaris and *BSD are now supported
• check_load is no longer needed

Author:

Patrick Kaell

patrick.kaell@police.etat.lu