check_apache_serverstatus

A Nagios plugin which uses the Apache server-status page to check that the server has enough free slots. The plugin also checks for an excessive number of slots in the R (reading request) state, which can be symptomatic of a slowloris-style denial of service attack.

Usage

Basic Usage:

check_apache_serverstatus.pl -H [IP]

Show full list of available options:

check_apache_serverstatus.pl --help

Prerequisites

1. The target Apache server must have mod_status enabled and visible at http://[IP]/server-status, and access to the server status page must be permitted from the Nagios server's IP.

2. The Nagios server must have the following Perl libraries installed (all available from CPAN):

   • Carp
   • Getopt::Std
   • Parse::Apache::ServerStatus
   • Math::Round

Example Apache Config

A sample of how Apache can be configured to enalbe the server status page. It would be advisible to add this in a separate .config file in the conf.d folder rater than directly in httpd.conf:

# This allows nagios to monitor apache
ExtendedStatus On

<Location /server-status>
SetHandler server-status

Order Deny,Allow
Deny from all
Allow from [nagios_server_ip] [other_trusted_ip(s)]
</Location>

Example Nagios Check Command

# check Apache status
define command{
    command_name    check_apache_status
    command_line    /usr/lib/nagios/plugins/check_apache_serverstatus.pl -H $HOSTADDRESS$
}