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| 2 | Nagios Installation and Configuration |
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| 3 | |
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| 4 | Notes: |
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| 5 | ------ |
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| 6 | * Commands preceded with "$" imply that you should execute the command as |
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| 7 | a general user - not as root. |
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| 8 | * Commands preceded with "#" imply that you should be working as root. |
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| 9 | * Commands with more specific command lines (e.g. "RTR-GW>" or "mysql>") |
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| 10 | imply that you are executing commands on remote equipment, or within |
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| 11 | another program. |
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| 12 | |
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| 13 | Exercises |
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| 14 | --------- |
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| 15 | |
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| 16 | Exercises Part I |
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| 17 | ---------------- |
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| 18 | |
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| 19 | 0. Log in to your PC or open a terminal window as the sysadm user. |
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| 20 | |
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| 21 | 1. You may need to install Nagios version 3. You would do this as root or as the sysadmin |
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| 22 | user and use the "sudo" command. As sysadm: |
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| 23 | |
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| 24 | $ sudo apt-get install nagios3 |
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| 25 | |
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| 26 | Unless you already have an MTA installed, nagios3 will install |
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| 27 | postfix as a dependency. Select "Internet Site" option. (If you had wanted |
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| 28 | to use a different MTA likely you'd install it before nagios3) |
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| 29 | |
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| 30 | You will be prompted for nagiosadmin password. Give it the normal |
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| 31 | workshop password. |
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| 32 | |
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| 33 | To get the documentation in /usr/share/doc/nagios3-doc/html/ (which |
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| 34 | can also be read via the nagios web interface), do: |
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| 35 | |
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| 36 | $ sudo apt-get install nagios3-doc |
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| 37 | |
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| 38 | |
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| 39 | 2. Look at the file which contains the password. It's hashed (encrypted) |
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| 40 | |
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| 41 | $ cat /etc/nagios3/htpasswd.users |
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| 42 | |
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| 43 | |
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| 44 | 3. You should already have a working Nagios! |
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| 45 | |
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| 46 | - Open a browser, and go to your machine like this: |
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| 47 | |
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| 48 | http://pcN.ws.nsrc.org/nagios3/ |
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| 49 | |
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| 50 | - At the login prompt, login as: |
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| 51 | |
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| 52 | user: nagiosadmin |
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| 53 | pass: <CLASS PASSWORD> |
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| 54 | |
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| 55 | Browse to the "Host Detail" page to see what's already configured. |
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| 56 | |
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| 57 | |
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| 58 | 4. Let's look at the configuration layout... But, first, let's become the root |
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| 59 | user on your machine: |
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| 60 | |
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| 61 | $ sudo bash |
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| 62 | |
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| 63 | # cd /etc/nagios3 |
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| 64 | # ls -l |
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| 65 | |
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| 66 | -rw-r--r-- 1 root root 1882 2008-12-18 13:42 apache2.conf |
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| 67 | -rw-r--r-- 1 root root 10524 2008-12-18 13:44 cgi.cfg |
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| 68 | -rw-r--r-- 1 root root 2429 2008-12-18 13:44 commands.cfg |
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| 69 | drwxr-xr-x 2 root root 4096 2009-02-14 12:33 conf.d |
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| 70 | -rw-r--r-- 1 root root 26 2009-02-14 12:36 htpasswd.users |
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| 71 | -rw-r--r-- 1 root root 42539 2008-12-18 13:44 nagios.cfg |
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| 72 | -rw-r----- 1 root nagios 1293 2008-12-18 13:42 resource.cfg |
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| 73 | drwxr-xr-x 2 root root 4096 2009-02-14 12:32 stylesheets |
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| 74 | |
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| 75 | # cd conf.d |
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| 76 | # ls -l |
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| 77 | |
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| 78 | -rw-r--r-- 1 root root 1695 2008-12-18 13:42 contacts_nagios2.cfg |
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| 79 | -rw-r--r-- 1 root root 418 2008-12-18 13:42 extinfo_nagios2.cfg |
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| 80 | -rw-r--r-- 1 root root 1152 2008-12-18 13:42 generic-host_nagios2.cfg |
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| 81 | -rw-r--r-- 1 root root 1803 2008-12-18 13:42 generic-service_nagios2.cfg |
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| 82 | -rw-r--r-- 1 root root 210 2009-02-14 12:33 host-gateway_nagios3.cfg |
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| 83 | -rw-r--r-- 1 root root 976 2008-12-18 13:42 hostgroups_nagios2.cfg |
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| 84 | -rw-r--r-- 1 root root 2167 2008-12-18 13:42 localhost_nagios2.cfg |
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| 85 | -rw-r--r-- 1 root root 1005 2008-12-18 13:42 services_nagios2.cfg |
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| 86 | -rw-r--r-- 1 root root 1609 2008-12-18 13:42 timeperiods_nagios2.cfg |
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| 87 | |
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| 88 | Notice that the package installs files with "nagios2" in their name. |
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| 89 | This is because they are the same files as were used for the Nagios |
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| 90 | version 2 Debian package. However there was a change made to the |
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| 91 | host-gateway configuration file, so this has a new name. |
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| 92 | |
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| 93 | |
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| 94 | 5. You have a config which is already monitoring your own system |
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| 95 | (localhost_nagios2.cfg) and your upstream default gateway |
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| 96 | (host-gateway_nagios3.cfg). |
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| 97 | |
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| 98 | Have a look at the config file for the default gateway: it's very simple. |
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| 99 | (Note: tab completion is useful here. Type cat host-g then hit tab; the |
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| 100 | filename will be filled in for you) |
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| 101 | |
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| 102 | # cat host-gateway_nagios3.cfg |
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| 103 | |
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| 104 | # a host definition for the gateway of the default route |
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| 105 | define host { |
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| 106 | host_name gateway |
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| 107 | alias Default Gateway |
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| 108 | address 10.10.0.254 |
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| 109 | use generic-host |
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| 110 | } |
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| 111 | |
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| 112 | |
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| 113 | |
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| 114 | PART II |
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| 115 | Configuring Equipment |
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| 116 | ----------------------------------------------------------------------------- |
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| 117 | |
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| 118 | 0. Order of configuration |
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| 119 | |
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| 120 | Conceptually we will build our configuration files from the "nearest" device |
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| 121 | then the further away ones. |
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| 122 | |
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| 123 | By going in this order you will have defined the devices that act as parents |
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| 124 | for other devices. |
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| 125 | |
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| 126 | Remember to refer to the Network Diagram for our classroom if you get confused. |
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| 127 | |
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| 128 | We have the following instances: |
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| 129 | |
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| 130 | rtr (the gateway router: 10.10.0.254) |
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| 131 | sw (the gateway switch: 10.10.0.253, parent: rtr) |
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| 132 | rtr1 (group 1 router: 10.10.0.201, parent: sw) |
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| 133 | rtr2 (group 2 router: 10.10.0.202, parent: sw) |
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| 134 | rtr3 (group 3 router: 10.10.0.203, parent: sw) |
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| 135 | rtr4 (group 4 router: 10.10.0.204, parent: sw) |
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| 136 | rtr5 (group 5 router: 10.10.0.205, parent: sw) |
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| 137 | |
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| 138 | pc1 (10.10.0.1, parent: sw) |
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| 139 | pc2 (10.10.0.2, parent: sw) |
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| 140 | ... |
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| 141 | pc29 (10.10.0.29, parent: sw) |
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| 142 | pc30 (10.10.0.30, parent: sw) |
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| 143 | |
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| 144 | s1 (10.10.0.241, parent: sw) |
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| 145 | s2 (10.10.0.242, parent: sw) |
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| 146 | noc (10.10.0.250, parent: sw) |
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| 147 | ap1 (10.10.0.251, parent: sw) |
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| 148 | ap2 (10.10.0.252, parent: sw) |
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| 149 | |
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| 150 | We recommend grouping these items in the files: |
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| 151 | |
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| 152 | routers.cfg (rtr, rtr1...rtr5) |
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| 153 | switches.cfg (sw) |
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| 154 | pcs.cfg (pc1...pc30, s1, s2, noc, ap1, ap2) |
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| 155 | |
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| 156 | |
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| 157 | 1. First we need to tell Nagios to monitor the gateway router for |
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| 158 | our classroom which is 10.10.0.254: |
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| 159 | |
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| 160 | # cd /etc/nagios3/conf.d/ |
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| 161 | |
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| 162 | Create the routers gateway like this: |
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| 163 | |
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| 164 | # editor routers.cfg |
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| 165 | |
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| 166 | define host { |
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| 167 | use generic-host |
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| 168 | host_name rtr |
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| 169 | alias Gateway Router |
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| 170 | address 10.10.0.254 |
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| 171 | } |
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| 172 | |
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| 173 | In the same file create the 5 entries for the group routers: |
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| 174 | |
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| 175 | define host { |
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| 176 | use generic-host |
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| 177 | host_name rtrX |
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| 178 | alias Group 1 Router |
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| 179 | address 10.10.0.20X |
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| 180 | parents sw |
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| 181 | } |
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| 182 | |
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| 183 | ... and replace 'X' in the definition above with the router number (1 - 5) |
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| 184 | |
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| 185 | repeate this for rtr2, rtr3, rtr4 and rtr5 |
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| 186 | |
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| 187 | Note that the entry for "sw" our gateway switch has not yet been created. That is |
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| 188 | next. |
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| 189 | |
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| 190 | Exit and save this file. |
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| 191 | |
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| 192 | |
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| 193 | 2. Create a file called switches.cfg and add an entry for this item: |
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| 194 | |
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| 195 | # editor switches.cfg |
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| 196 | |
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| 197 | define host { |
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| 198 | use generic-host |
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| 199 | host_name sw |
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| 200 | alias Backbone Switch |
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| 201 | address 10.10.0.253 |
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| 202 | parents rtr |
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| 203 | } |
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| 204 | |
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| 205 | At this point Nagios is configured to monitor whether our core hosts (the parents) |
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| 206 | are up on our classroom network. Your next steps are to add in the individual hosts |
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| 207 | such as the classroom virtual PC images on your table (for example for group 1, |
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| 208 | pc1 - 6, for group 2, pc7 - 12, etc.), the Wireless Access Points (ap1 and ap2), |
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| 209 | the servers s1, s2 and the noc: |
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| 210 | |
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| 211 | Be sure you add in a proper "parents" entry for each host. |
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| 212 | |
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| 213 | Remember, if you don't understand the parent relations in our network you can |
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| 214 | review the logical network diagram here: |
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| 215 | |
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| 216 | http://noc.ws.nsrc.org/sanog18/wiki/NetworkDiagram |
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| 217 | |
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| 218 | Note the Nagios parent bullet points in the slides! |
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| 219 | |
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| 220 | Nagios Parent Relationships |
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| 221 | |
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| 222 | |
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| 223 | STEPS 2a - 2c SHOULD BE REPEATED WHENEVER YOU UPDATE THE CONFIGURATION! |
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| 224 | |
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| 225 | |
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| 226 | 2a. Verify that your configuration files are OK: |
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| 227 | |
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| 228 | # nagios3 -v /etc/nagios3/nagios.cfg |
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| 229 | |
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| 230 | ... You should get some warnings like : |
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| 231 | Warning: Host 'rtr' has no services associated with it! |
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| 232 | Warning: Host 'sw' has no services associated with it! |
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| 233 | etc.... |
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| 234 | ... |
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| 235 | Total Warnings: N |
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| 236 | Total Errors: 0 |
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| 237 | |
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| 238 | Things look okay - No serious problems were detected during the check. |
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| 239 | Nagios is saying that it's unusual to monitor a device just for its |
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| 240 | existence on the network, without also monitoring some service. |
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| 241 | |
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| 242 | |
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| 243 | 2b. Reload/Restart Nagios |
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| 244 | |
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| 245 | # /etc/init.d/nagios3 restart |
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| 246 | |
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| 247 | Not always 100% reliable to use the "restart" option due to a bug in the Nagios init script. |
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| 248 | To be sure you may want to get used to doing: |
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| 249 | |
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| 250 | # /etc/init.d/nagios3 stop |
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| 251 | # /etc/init.d/nagios3 start |
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| 252 | |
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| 253 | |
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| 254 | 2c. Go to the web interface (http://pcN.ws.nsrc.org/nagios3) and check that the hosts |
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| 255 | you just added are now visible in the interface. Click on the "Host Detail" item |
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| 256 | on the left of the Nagios screen to see this. You may see it in "PENDING" |
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| 257 | status until the check is carried out. |
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| 258 | |
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| 259 | |
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| 260 | HINT: You will be doing this a lot. If you do it all on one line, like this, |
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| 261 | then you can hit cursor-up and rerun all in one go: |
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| 262 | |
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| 263 | nagios3 -v /etc/nagios3/nagios.cfg && /etc/init.d/nagios3 restart |
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| 264 | |
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| 265 | The '&&' ensures that the restart only happens if the config is valid. |
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| 266 | |
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| 267 | |
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| 268 | 3. Create entries for the classroom PCs |
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| 269 | |
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| 270 | Now that we have our routers and switches defined it is quite easy to create |
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| 271 | entries for all our PCs. Think about the parent relationships: |
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| 272 | |
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| 273 | Remember, if you do not understand the parent relationship refer back to the |
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| 274 | classroom network diagram here: |
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| 275 | |
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| 276 | http://noc.ws.nsrc.org/sanog18/wiki/NetworkDiagram |
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| 277 | |
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| 278 | Below are three sample entries. One for the NOC, one for pc1 and one for |
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| 279 | pc6. You should be able to use this example to create entries for all |
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| 280 | classroom PCs plus the NOC. |
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| 281 | |
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| 282 | We could put these entries in to separate files, but as our network is small |
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| 283 | we'll use a single file called pcs.cfg. |
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| 284 | |
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| 285 | NOTE! You do not add in an entry for your own PC or router. This has already |
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| 286 | been defined in the file /etc/nagios3/conf.d/localhost_nagios2.cfg. This |
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| 287 | definition is what defines the Nagios network viewpoint. So, when you come to |
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| 288 | the spot where you might add an entry for your PC you should skip this and go |
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| 289 | on to the next PC in the list. |
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| 290 | |
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| 291 | # editor pcs.cfg |
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| 292 | |
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| 293 | # Our classroom NOC |
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| 294 | |
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| 295 | define host { |
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| 296 | use generic-host |
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| 297 | host_name noc |
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| 298 | alias Workshop NOC machine |
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| 299 | address 10.10.0.250 |
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| 300 | parents sw |
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| 301 | } |
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| 302 | |
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| 303 | # PCs |
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| 304 | |
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| 305 | define host { |
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| 306 | use generic-host |
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| 307 | host_name pc1 |
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| 308 | alias pc1 |
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| 309 | address 10.10.0.1 |
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| 310 | parents sw |
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| 311 | } |
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| 312 | |
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| 313 | define host { |
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| 314 | use generic-host |
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| 315 | host_name pc6 |
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| 316 | alias pc6 |
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| 317 | address 10.10.0.6 |
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| 318 | parents sw |
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| 319 | } |
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| 320 | |
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| 321 | Pay attention to the parent entries and the IP addresses. |
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| 322 | |
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| 323 | Take the three entries above and now expand this to create the remaining |
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| 324 | entries for the PCs in your group. That is, if you are in group 1, fill in |
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| 325 | for PCs 2 through 5 (rememember to skip your own PC!). |
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| 326 | |
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| 327 | |
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| 328 | Exit and save the file pcs.cfg |
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| 329 | |
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| 330 | As before, repeat steps 2a-2c to verify your configuration, correct any |
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| 331 | errors, and activate it. |
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| 332 | |
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| 333 | 5. Look at your Nagios instance on the web. Note that "Status Map" gives |
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| 334 | you a graphical view of the parent-child relationships you have defined. |
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| 335 | |
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| 336 | |
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| 337 | PART III |
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| 338 | Configure Service check for the classroom NOC |
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| 339 | ----------------------------------------------------------------------------- |
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| 340 | |
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| 341 | 0. Configuring |
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| 342 | |
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| 343 | Now that we have our hardware configured we can start telling Nagios what services to monitor |
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| 344 | on the configured hardware, how to group the hardware in interesting ways, how to group |
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| 345 | services, etc. |
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| 346 | |
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| 347 | 1. Associate a service check for our classroom NOC |
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| 348 | |
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| 349 | # editor hostgroups_nagios2.cfg |
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| 350 | |
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| 351 | - Find the hostgroup named "ssh-servers". In the members section of the defintion |
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| 352 | change the line: |
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| 353 | |
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| 354 | members localhost |
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| 355 | |
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| 356 | to |
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| 357 | |
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| 358 | members localhost,noc |
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| 359 | |
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| 360 | Exit and save the file. |
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| 361 | |
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| 362 | Verify that your changes are OK: |
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| 363 | |
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| 364 | # nagios3 -v /etc/nagios3/nagios.cfg |
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| 365 | |
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| 366 | Restart Nagios to see the new service assocation with your host: |
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| 367 | |
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| 368 | # /etc/init.d/nagios3 restart |
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| 369 | |
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| 370 | Click on the "Service Detail" link in the Nagios web interface to see your new entry. |
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| 371 | |
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| 372 | |
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| 373 | PART IV |
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| 374 | Defining Services for all PCs |
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| 375 | ----------------------------------------------------------------------------- |
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| 376 | |
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| 377 | 0. For services, the default normal_check_interval is 5 (minutes) in |
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| 378 | generic-service_nagios2.cfg. You may wish to change this to 1 to speed up |
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| 379 | how quickly service issues are detected, at least in the workshop. |
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| 380 | |
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| 381 | 1. Determine what services to define for what devices |
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| 382 | |
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| 383 | - This is core to how you use Nagios and network monitoring tools in |
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| 384 | general. So far we are simply using ping to verify that physical hosts |
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| 385 | are up on our network and we have started monitoring a single service on |
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| 386 | a single host (your PC). The next step is to decide what services you wish |
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| 387 | to monitor for each host in the classroom. |
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| 388 | |
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| 389 | - In this particular class we have: |
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| 390 | |
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| 391 | routers: running ssh and snmp |
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| 392 | switches: running telnet and possibly ssh as well as snmp |
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| 393 | pcs: All PCs are running ssh and http and should be running snmp |
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| 394 | The NOC is currently running an snmp daemon |
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| 395 | |
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| 396 | So, let's configure Nagios to check for these services for these |
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| 397 | devices. |
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| 398 | |
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| 399 | 2.) Verify that SSH is running on the routers and workshop PCs images |
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| 400 | |
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| 401 | - In the file services_nagios2.cfg there is already an entry for the SSH |
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| 402 | service check, so you do not need to create this step. Instead, you |
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| 403 | simply need to re-define the "ssh-servers" entry in the file |
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| 404 | /etc/nagios3/conf.d/hostgroups_nagios2.cfg. The initial entry in the file |
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| 405 | looked like: |
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| 406 | |
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| 407 | # A list of your ssh-accessible servers |
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| 408 | define hostgroup { |
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| 409 | hostgroup_name ssh-servers |
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| 410 | alias SSH servers |
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| 411 | members localhost,noc |
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| 412 | } |
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| 413 | |
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| 414 | What do you think you should change? Correct, the "members" line. You should |
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| 415 | add in entries for all the classroom pcs, routers and the switches that run ssh. |
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| 416 | With this information and the network diagram you should be able complete this entry. |
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| 417 | |
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| 418 | The entry will look something like this: |
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| 419 | |
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| 420 | define hostgroup { |
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| 421 | hostgroup_name ssh-servers |
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| 422 | alias SSH servers |
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| 423 | members localhost,pc1,pc2,pc3,...,pc6,ap1,ap2,s1,s2,noc |
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| 424 | } |
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| 425 | |
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| 426 | Note: leave in "localhost" - This is your PC and represents Nagios' network point of |
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| 427 | view. So, for instance, if you are on "pc3" you would not include "pc3" in the list |
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| 428 | of all the classroom pcs as it is represented by the "localhost" entry. |
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| 429 | |
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| 430 | The "members" entry will be a long line and will likely wrap on the screen. |
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| 431 | |
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| 432 | Remember to include all the PCs on your table and the routers that you have defined. Do no |
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| 433 | include any entries if they are not already defined in pcs.cfg, switches.cfg or |
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| 434 | routers.cfg. |
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| 435 | |
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| 436 | - Once you are done, run the pre-flight check: |
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| 437 | |
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| 438 | # nagios3 -v /etc/nagios3/nagios.cfg |
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| 439 | |
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| 440 | If everything looks good, then restart Nagios |
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| 441 | |
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| 442 | # /etc/init.d/nagios3 stop |
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| 443 | # /etc/init.d/nagios3 start |
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| 444 | |
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| 445 | and view your changes in the Nagios web interface. |
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| 446 | |
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| 447 | To continue with hostgroups you can add additional groups for later use, such as all our virtual |
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| 448 | servers. Go ahead and edit the file hostgroups_nagios2.cfg again: |
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| 449 | |
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| 450 | # editor hostgroups_nagios2.cfg |
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| 451 | |
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| 452 | and add the following to the end of the file: |
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| 453 | |
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| 454 | # A list of our virtual routers |
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| 455 | define hostgroup { |
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| 456 | hostgroup_name cisco7200 |
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| 457 | alias Cisco 7200 Routers |
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| 458 | members rtr1,rtr2,rtr3,rtr4,rtr5,rtr6 |
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| 459 | } |
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| 460 | |
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| 461 | Save and exit from the file. Verify that everything is OK: |
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| 462 | |
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| 463 | # nagios3 -v /etc/nagios3/nagios.cfg |
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| 464 | |
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| 465 | If everything looks good, then restart Nagios |
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| 466 | |
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| 467 | # /etc/init.d/nagios3 stop |
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| 468 | # /etc/init.d/nagios3 start |
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| 469 | |
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| 470 | 3.) Check that http is running on all the classroom PCs. |
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| 471 | |
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| 472 | - This is almost identical to the previous exercise. Just make the change to the |
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| 473 | HTTP service adding in each PC (no routers or switches). Remember, you don't need |
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| 474 | to add your machine as it is already defined as "localhost". |
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| 475 | |
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| 476 | Find the definition in hostgroups_nagios2.cfg: |
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| 477 | |
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| 478 | define hostgroup { |
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| 479 | hostgroup_name http-servers |
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| 480 | alias HTTP servers |
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| 481 | members localhost |
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| 482 | } |
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| 483 | |
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| 484 | and after localhost, add all the PCs on your table |
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| 485 | |
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| 486 | |
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