Nagios and GVFS problem

1. Nagios on RHEL or Fedora

install packages:

• on Fedora8 - install nagios and complete set of plugins:

yum install -y nagios nagios-plugins-all nagios-plugins-ifstatus
               nagios-plugins-ifoperstatus nagios-plugins-snmp-disk-proc

this will install

and additional software: fping, perl-Crypt-DES, perl-Digest-HMAC, perl-Net-SNMP, qstat

• on RHEL4 - install nagios 2.12 using apt/dag:

apt-get install -y nagios nagios-plugins nagios-nrpe
                   nagios-plugins-setuid nagios-plugins-nrpe

Configure apache:

• disable default apache configuration

cd /etc/httpd/conf.d
mv nagios.conf nagios.conf.disable

• verify the nagios locations of apache config - directory locations differ between systems
  • on FC8 i386 directories are: /usr/lib/nagios/cgi-bin/ /usr/share/nagios/html/
  • on RHEL4 x86_64 directories are: /usr/lib64/nagios/cgi /usr/share/nagios
• create wiki links

Install windows agent:

• download NC_Net_setupV4.4.0.msi from the NC-NET project on sourceforge and start MSI setup
• start the NC_NET service
• the documentation can be taken from installed distribution NC_Net-4.4-WinDir.tgz

Configure nagios:

• download and unpack /etc/nagios from v1.tgz or v2.tgz
• adjust configuration to your taste
• verify config files

nagios -v /etc/nagios/nagios.cfg

• start service

chkconfig nagios on
service nagios restart

Note that Nagios checks SSH on server using commonplace port 22inspite of the  port numbering trick.

2. Nagios on Ubuntu

Install the packages

apt-get install -y apache2 nagios2 nagios-plugins-basic

Create the password file

htpasswd -c -b /etc/nagios2/htpasswd.users nagiosadmin nagiosadmin

Pinging of a VPN address (e.g. 10.20.3.2) would not work after that. Change /etc/nagios2/conf.d/host-gateway_nagios2.cfg:

host_name gateway
address 10.20.3.2

Create configuration file for webserver /etc/nagios2/conf.d/server.cfg:

# check domain server

define host{
        use                     generic-host
        host_name               webserver
        alias                   server.ourdom.com
        address                 172.16.162.57
        }

define command{
        command_name    check_cups_http
        command_line    $USER1$/check_http -H $ARG1$ -p 631
        }

define command{
        command_name    check_dns
        command_line    $USER1$/check_dns -H www.yahoo.com -s $HOSTADDRESS$
        }

define command{
        command_name    check_ssh_nonstd
        command_line    $USER1$/check_ssh -H $HOSTADDRESS$ -p $ARG1$ -t $ARG2$
        }

define service{
        use                     generic-service
        host_name               webserver
        service_description     PING
        check_command           check_ping!100.0,20%!500.0,60%
        }

# minimal package does not have check_dns
#define service{
#       use                     generic-service         
#       host_name               webserver
#       service_description     DNS service
#       check_command           check_dns
#       }

define service{
        use                     generic-service         
        host_name               webserver
        service_description     FTP service
        check_command           check_ftp
        }

define service{
        use                     generic-service         
        host_name               webserver
        service_description     HTTP service
        check_command           check_http
        }

define service{
        use                     generic-service         
        host_name               webserver
        service_description     SMTP service
        check_command           check_smtp
        }

define service{
        use                     generic-service         
        host_name               webserver
        service_description     SSH service
        check_command           check_ssh_nonstd!13577!10
        }

define service{
        use                     generic-service         
        host_name               webserver
        service_description     Printing
        check_command           check_cups_http!vpn
        }

Note that we define a special check_ssh_nonstd command to check the SSH health on server. In our setup it is required because of the port numbering trick.

Now verify the configuration and restart Nagios

nagios2 -v /etc/nagios2/nagios.cfg
/etc/init.d/nagios2 restart
/etc/init.d/apache2 restart

Point your web browser to the nagios page, in our case http://ttk.ourdom.com/nagios2

3. GVFS problem on Ubuntu

Installed on Ubuntu 8, Nagios manifests the following error message

DISK CRITICAL - /home/support/.gvfs is not accessible: Permission denied

My investigation showed that this problem appears due to special permissions set by FUSE on the .gvfs directory: nobody, even root cannot access it. It is only used internally by FUSE. This problem is discussed in the relevant ubuntu bug report. Workaround for nagios is discussed here. We use the "-i ignored_path" key of the check_disk plugin.

So, in my case I modified /etc/nagios2/conf.d/localhost_nagios2.cfg in the following way:

define command{
  command_name  check_all_disks_plus
  command_line  /usr/lib/nagios/plugins/check_disk -w $ARG1$ -c $ARG2$ -u GB -A -i .gvfs
  }

define service{
  use                  generic-service
  host_name            localhost
  service_description  Disk Space
  check_command        check_all_disks_plus!20%!10%
  }

4. Contact e-mail

Finally, I needed to let Nagios contact administrators via mail server, in my case the CommuniGate mailer installed on the SOHO server. I performed these steps:

1. Add nagios-tk as a postmaster alias in CGPro
2. Change host name in /etc/nagios2/conf.d/localhost_nagios2.cfg to tk.home
3. Use nagios-tk@ourdom.com as contact email in /etc/nagios2/conf.d/contacts_nagios2.cfg

Of course, server and mail naming conventions in your setup will be different.

Attachments

NC_Net_setupV4.4.0.msi

NC_Net_setupV4.4.0.msi 783 KB

NC_Net-4.4-WinDir.tgz

NC_Net-4.4-WinDir.tgz 277.05 KB

ps-etc-nagios-v01.tgz

ps-etc-nagios-v01.tgz 38.12 KB

ps-etc-nagios-v02.tar.gz

ps-etc-nagios-v02.tar.gz 77.95 KB