Each item is a child of either a switch or a router in our classroom, EXCEPT for your gateway router (rtrX) and the other members of your group. We are now going to add a "parents" statement for each device we have configured.
If you are unsure of the parent relationships you can look at our classroom Network Diagram. Remember, the parent relationships are from the point of view of your Nagios instance running on your pc.
$ cd /etc/nagios3/conf.d
$ sudo editor switches.cfgUpdate the entry:
define host {
use generic-host
host_name sw
alias Backbone Switch
address 10.10.0.253
}to be
define host {
use generic-host
host_name sw
alias Backbone Switch
address 10.10.0.253
parents rtrX
}Where "rtrX" is the gateway router for your group. I.E., for group 1 you would use "rtr1", for group 2, "rtr2" and so forth.
Save and exit from the file.
$ sudo editor routers.cfgFor each entry we will add a "parents" line. So, for the gw definition at the top of the file this should now look like:
define host {
use generic-host
host_name gw
alias Classrooom Gateway Router
address 10.10.0.254
parents sw
}For all the remaining rtrX entries you should, also, add a line that says:
parents swEXCEPT For the rtrX entry for your group. There should be NO PARENTS entry. If you have an entry for "ap1" (classroom wireless access point), then the parents entry is, also, "sw" - same as the other routers.
So, if you are in group 2, then the entries for groups 1, 2 and 3 would look like:
define host {
use generic-host
host_name rtr1
alias Group 1 Router
address 10.10.1.254
parents sw
}
define host {
use generic-host
host_name rtr2
alias Group 2 Router
address 10.10.2.254
}
define host {
use generic-host
host_name rtr3
alias Group 3 Router
address 10.10.3.254
parents sw
}Update the rest of the file correctly and then save and exit from the file.
For all the PC entries you should add a "parents" line that has the router for that PC's group. For the noc the parent is the core switch or "sw"
#
# Classroom NOC
#
define host {
use generic-host
host_name noc
alias Workshop NOC machine
address 10.10.0.250
parents sw
}
For PCs in Group 1 entries look like:
#
# Group 1
#
define host {
use generic-host
host_name pc1
alias pc1
address 10.10.1.1
parents rtr1
}
define host {
use generic-host
host_name pc2
alias pc2
address 10.10.1.2
parents rtr1
}
etc
Do this for all the PCs in the remaining groups. I.E., pc5 in Group 2 has a parents statement of:
parents rtr2BUT, FOR THE 4 ENTRIES FOR THE PCS IN YOUR GROUP DO NOT ADD ANY PARENTS STATEMENT! REPEAT - THE PCS IN YOUR GROUP DO NOT HAVE ANY PARENT ENTRY!
Save and exit from the file.
$ sudo service nagios3 restartIf you have errors, fix these and try restarting again.
Open a web browser to http://pcN.ws.nsrc.org/nagios3 and click on the "Map" link on the left. Your map should now look quite different. You should see a map that represents the Nagios world point of view from your machine.
In the web view, look at the pages "Hostgroup Overview", "Hostgroup Summary", "Hostgroup Grid". This gives a convenient way to group together hosts which are related (e.g. in the same site, serving the same purpose).
For the following exercises it will be very useful if we have created or update the following hostgroups:
debian-servers
routers
switchesIf you edit the file /etc/nagios3/conf.d/hostgroups_nagios2.cfg you will see an entry for debian-servers that just contains localhost. Update this entry to include all the classroom PCs, including the noc (this assumes that you created a "noc" entry in your pcs.cfg file). Remember to skip your PC entry as it is represented by the localhost entry.
$ sudo editor /etc/nagios3/conf.d/hostgroups_nagios2.cfgUpdate the entry that says:
# A list of your Debian GNU/Linux servers
define hostgroup {
hostgroup_name debian-servers
alias Debian GNU/Linux Servers
members localhost
}So that the "members" parameter contains something like this. Use your classroom network diagram to confirm the exact number of machines and names in your workshop.
members localhost,pc1,pc2,pc3,pc4,pc5,pc6,pc7,pc8,pc9,pc10,pc11,pc12, \
pc13,pc14,pc15,pc16,pc17,pc18,pc19,pc20,pc21,pc22,pc23,pc24,pc25,\
pc26,pc27,pc28,pc29,pc30,pc31,pc32,pc33,pc34,pc35,pc36Be sure that the end of the line has a "" to indicate a new line. Otherwise you will get an error when you go to restart Nagios. Remember that your own PC is "localhost", so skip your pc entry.
Once you have done this, add one more host group for our classroom switch(es). If there is more than just one switch (sw.ws.nsrc.org) include this on the members line below, otherwise the entry at the end of the hostgroups_nagios2.cfg file should look like (COPY and PASTE):
# A list of our switches
define hostgroup {
hostgroup_name switches
alias Classroom Switches
members sw
}When you are done be sure to verify your work and restart Nagios.
If you would like to use appropriate icons for your defined hosts in Nagios this is where you do this. We have the three types of devices:
There is a fairly large repository of icon images available for you to use located here:
/usr/share/nagios/htdocs/images/logos/these were installed by default as dependent packages of the nagios3 package in Ubuntu. In some cases you can find model-specific icons for your hardware, but to make things simpler we will use the following icons for our hardware:
/usr/share/nagios/htodcs/images/logos/base/debian.*
/usr/share/nagios/htdocs/images/logos/cook/router.*
/usr/share/nagios/htdocs/images/logos/cook/switch.*The next step is to edit the file /etc/nagios3/conf.d/extinfo_nagios2.cfg and tell nagios what image you would like to use to represent your devices.
$ sudo editor /etc/nagios3/conf.d/extinfo_nagios2.cfgHere is what an entry for your routers looks like (there is already an entry for debian-servers that will work as is). Note that the router model (3600) is not all that important. The image used represents a router in general.
define hostextinfo {
hostgroup_name routers
icon_image cook/router.png
icon_image_alt Cisco Routers (7200)
vrml_image router.png
statusmap_image cook/router.gd2
}Note how we can simply use "hostgroup_name routers" as this has already been defined in the file hostgroups_nagios2.cfg. This makes configuring multiple, like items much simpler.
Now add an entry for your switches. Once you are done check your work and restart Nagios. Take a look at the Status Map in the web interface (Map link on the left). It should be much nicer, with real icons instead of question marks for most items.
The idea here is to create three service groups. Each service group will be for a quarter of the classroom. We want to see these PCs grouped together and include status of their ssh and http services. To do this edit and create the file:
$ cd /etc/nagios3/conf.d (just to be sure)
$ sudo editor servicegroups.cfgHere is a sample of the service group for group 1:
define servicegroup {
servicegroup_name group1-services
alias group 1 services
members pc1,SSH,pc1,HTTP,pc2,SSH,pc2,HTTP,pc3,SSH,pc3,HTTP,pc4,SSH,pc4,HTTP
}Note that if the members line is too long you can use the "" at the end to create a new line of members just below.
Note that "SSH" and "HTTP" need to be uppercase as this is how the service_description is written in the file /etc/nagios3/conf.d/services_nagios2.cfg
You should create an entry for other groups of servers too.
CRITICAL - When you create an entry for your group remember to use "localhost" instead of your "pcN" name since you have only defined your pc as localhost in the file hostgroups_nagios2.cfg.
Save your changes, verify your work and restart Nagios. Now if you click on the Service Groups menu item in the Nagios web interface you should see this information grouped together.
By default Nagios is configured to give full r/w access via the Nagios web interface to the user nagiosadmin. You can change the name of this user, add other users, change how you authenticate users, what users have access to what resources and more via the cgi.cfg file.
First, lets create a "guest" user and password in the htpasswd.users file.
$ sudo htpasswd /etc/nagios3/htpasswd.users guestYou can use any password you want (or none). A password of "guest" is not a bad choice.
Next, edit the file /etc/nagios3/cgi.cfg and look for what type of access has been given to the nagiosadmin user. By default you will see the following directives (note, there are comments between each directive):
authorized_for_system_information=nagiosadmin
authorized_for_configuration_information=nagiosadmin
authorized_for_system_commands=nagiosadmin
authorized_for_all_services=nagiosadmin
authorized_for_all_hosts=nagiosadmin
authorized_for_all_service_commands=nagiosadmin
authorized_for_all_host_commands=nagiosadminNow let's tell Nagios to allow the "guest" user some access to information via the web interface. You can choose whatever you would like, but what is pretty typical is this:
authorized_for_system_information=nagiosadmin,guest
authorized_for_configuration_information=nagiosadmin,guest
authorized_for_system_commands=nagiosadmin
authorized_for_all_services=nagiosadmin,guest
authorized_for_all_hosts=nagiosadmin,guest
authorized_for_all_service_commands=nagiosadmin
authorized_for_all_host_commands=nagiosadminNote we do not give the guest user access to system commands, service commands nor host commands.
Once you make the changes, save the file cgi.cfg, verify your work and restart Nagios.
To see if you can log in as the "guest" user you will need to clear the cookies in your web browser or open an alternate web browser if you have one. You will not notice any difference in the web interface. The difference is that a number of items that are available via the web interface (forcing a service/host check, scheduling checks, comments, etc.) will not work for the guest user.
This change is required in order to allow users to "Acknowledge" problems with hosts and services in the Web interface. The default file permissions are set up in a secure way to prevent the web interface from updating nagios, so you need to make them slightly more permissive.
First, edit the file "/etc/nagios3/nagios.cfg", and change the line:
check_external_commands=0to
check_external_commands=1Save the file and exit.
Then, perform the following commands to change directory permissions and to make the changes permanent:
$ sudo /etc/init.d/nagios3 stop
$ sudo dpkg-statoverride --update --add nagios www-data 2710 /var/lib/nagios3/rw
$ sudo dpkg-statoverride --update --add nagios nagios 751 /var/lib/nagios3
$ sudo /etc/init.d/nagios3 startOnce this is done, go to "Problems" > "Services (Unhandled)" and find a service in the red (critical) or yellow (warning) state. Click on the service name. Then under "Service commands" click on "Acknowledge this service problem".
The problem should disappear from the list of unhandled problems.