Nagios

Installing Nagios Important: Installing and configuring Nagios is rather involved. You can't just compile the binaries, run the program and sit back. There's a lot to setup before you can actually start monitoring anything. Relax, take your time and read all the documentation - you're going to need it. Okay, let's get started... Become Root You'll need to have root access to install Nagios as described in this documentation, as you'll be creating users and group, modifying your web server config files, etc. Either login as root before you begin or use the su command to change to the root user from another account. Getting The Latest Version You can download the latest version of Nagios from . Unpacking The Distribution To unpack the Nagios distribution, use the following command: tar xzf nagios-version.tar.gz When you have finished executing these commands, you should find a nagios-version directory that has been created in your current directory. Inside that directory you will find all the files that comprise the core Nagios distribution. Create Nagios User/Group You're probably going to want to run Nagios under a normal user account, so add a new user (and group) to your system with the following command (this will vary depending on what OS you're running): adduser nagios Create Installation Directory Create the base directory where you would like to install Nagios as follows... mkdir /usr/local/nagios Change the owner of the base installtion directory to be the Nagios user and group you added earlier as follows: chown nagios.nagios /usr/local/nagios Identify Web Server User You're probably going to want to issue external commands <extcommands.html> (like acknowledgements and scheduled downtime) from the web interface. To do so, you need to identify the user your web server runs as (typically apache, although this may differ on your system). This setting is found in your web server configuration file. The following command can be used to quickly determine what user Apache is running as (paths may differ on your system): grep "^User" /etc/httpd/conf/httpd.conf Add Command File Group Next we're going to create a new group whose members include the user your web server is running as and the user Nagios is running as. Let's say we call this new group 'nagcmd' (you can name it differently if you wish). On RedHat Linux you can use the following command to add a new group (other systems may differ): /usr/sbin/groupadd nagcmd Next, add the users that your web server and Nagios run as to the newly created group with the following commands (I'll assume apache and nagios are the respective users): /usr/sbin/usermod -G nagcmd apache /usr/sbin/usermod -G nagcmd nagios Run the Configure Script Run the configure script to initialize variables and create a Makefile as follows...(the last two options: -with-command-xxx are optional, but needed if you want to issue external commands <extcommands.html>) ./configure --prefix=prefix --with-cgiurl=cgiurl --with-htmurl=htmurl --with-nagiosuser=someuser --with-nagios-group=somegroup --with-command-group=cmdgroup • Replace prefix with the installation directory that you created in the step above (default is /usr/local/nagios) • Replace cgiurl with the actual url you will be using to access the CGIs (default is /nagios/cgi-bin). Do NOT append a slash at the end of the url.

Replace htmurl with the actual url you will be using to access the HTML for the main interface and documentation (default is /nagios/) • Replace someuser with the name of a user on your system that will be used for setting permissions on the installed files (default is nagios) • Replace somegroup with the name of a group on your system that will be used for setting permissions on the installed files (default is nagios) • Replace cmdgroup with the name of the group running the web server (default is nagios, in the example above it was nagcmd). This will allow group members (i.e. your web server) to be able to submit external commands to Nagios. Compile Binaries Compile Nagios and the CGIs with the following command: make all Installing The Binaries And HTML Files Install the binaries and HTML files (documentation and main web page) with the following command: make install Installing An Init Script If you wish, you can also install the sample init script to /etc/rc.d/init.d/nagios with the following command: make install-init You may have to edit the init script to make sense with your particular OS and Nagios installation by editing paths, etc. Directory Structure And File Locations Change to the root of your Nagios installation directory with the following command... cd /usr/local/nagios You should see five different subdirectories. A brief description of what each directory contains is given in the table below. Sub-DirectoryContentsbin/Nagios core programetc/Main , resource , object , and CGI configuration files should be put heresbin/CGIs share/HTML files (for web interface and online documentation)var/Empty directory for the log file , status file , retention file , etc.var/archivesEmpty directory for the archived logs var/rwEmpty directory for the external command file Installing The Plugins In order for Nagios to be of any use to you, you're going to have to download and install some . Plugins are usually installed in the libexec/ directory of your Nagios installation (i.e. /usr/local/nagios/libexec). Plugins are scripts or binaries which perform all the service and host checks that constitute monitoring. You can grab the latest release of the plugins from the Nagios downloads page or directly from the SourceForge project page . Setup The Web Interface You're probably going to want to use the web interface, so you'll also have to read the instructions on setting up the web interface and configuring web authentication, etc. next. Configuring Nagios So now you have things compiled and installed, but you still haven't configured Nagios or defined objects (hosts, services, etc.) that should be monitored. Information on configuring Nagios and defining objects can be found here . There's a lot to configure, but don't let it discourage you - its well worth it. Restart The Web Server Once you've finished editing the Apache configuration file, you'll need to restart the web server with a command like this... /etc/rc.d/init.d/httpd restart •

Setting Up Authenticated Users If you haven't done so already, you'll need to add the appropriate entries to your web server config file

to enable basic authentication for the CGI and HTML portions of the Nagios web interface. Instructions for doing so can be found here . Now that you've configured your web server to require authentication for the Nagios web interface, you'll need to specify who has access. This is done by using the htpasswd command supplied with Apache. Running the following command will create a new file called htpasswd.users in the /usr/local/nagios/etc directory. It will also create an username/password entry for nagiosadmin. You will be asked to provide a password that will be used when nagiosadmin authenticates to the web server. htpasswd -c /usr/local/nagios/etc/htpasswd.users nagiosadmin Continue adding more users until you've created an account for everyone you want to access the CGIs. Use the following command to add additional users, replacing <username> with the actual username you want to add. Note that the -c option is not used, since you already created the initial file. htpasswd /usr/local/nagios/etc/htpasswd.users <username> Okay, so you're done with the first part of what needs to be done. At this point you should be prompted for a username and password if you point your web browser to the Nagios web interface. If you have problems getting user authentication to work at this point, read your webserver documentation for more info. Verify Your Changes Don't forget to check and see if the changes you made to Apache work. You should be able to point your web browser at http://yourmachine/nagios/ and get the web interface for Nagios. The CGIs may not display any information, but this will be remedied once you configure everything and start Nagios.