My Notes for Installing Nagios on Ubuntu Server 12.04 LTS

[LHammonds]

Greetings and salutations,

I hope this thread will be helpful to those who follow in my foot steps as well as getting any advice based on what I have done / documented.

This is a Work-In-Progress topic so I will be updating this thread as I complete/update my notes.

High-level overview

This thread will cover installation of a dedicated Ubuntu server and Nagios monitoring system. The server will be installed inside a virtual machine vSphere 4.1 running on ESXi 4.1 servers. I will also supply notes for doing the same thing for Oracle's VirtualBox on a Windows 7 PC. Although there are some VMware-specific and VirtualBox-specific steps, they are very few and the majority of this documentation will work for other Virtual Machines or even directly installed onto a physical machine (e.g. bare-metal install). Please excuse any ignorance on my part since I am fairly new to Linux...if you have any advice on doing things better, please let me know. I love feedback and learning better ways of doing things!

This thread will also cover some custom scripts to help automate tasks such as backing up, automatically growing the file system when free space is low, etc.

I choose to build Nagios from the source download rather than install from the repository with aptitude / apt-get. The reason is that you get the newer version this way and you have full control over the installation options.

This documentation will only cover a very specific installation. Nagios was designed to be able to handle just about anything you want to monitor so it will be different for each install and even with the same hardware needing to be monitored, two administrators may decide differently on what needs to be monitored.

Tools utilized in this process

• Ubuntu Server 12.04 LTS, 64-bit
• Nagios 3.4.1
• Portable PuTTY 0.62
• VMware vSphere 4.1.0
• VirtualBox 4.1.16

Helpful links

The list below are sources of information that helped me configure this system as well as some places that might be helpful to me later on as this process continues.

• Ubuntu Documentation
• Ubuntu Firewall Basics
• A primer on Iptables
• Ubuntu AppArmor Basics
• InstallationWiki - Nagios

Assumptions

This documentation will need to make use of some very-specific information that will most-likely be different for each person / location. And as such, I will note some of these in this section. They will be highlighted in red throughout the document as a reminder that you should plug-in your own value rather than actually using my "place-holder" value.

Under no circumstance should you use the actual values I list below. They are place-holders for the real thing. This is just a checklist template you need to have answered before you start the install process.

Wherever you see RED in this document, you need to substitute it for what your company uses. Use the list below as a template you need to have answered before you continue.

• Ubuntu Server name: srv-nagios
• Internet domain: mydomain.com
• Ubuntu Server IP address: 192.168.107.21
• Ubuntu Server IP subnet mask: 255.255.255.0
• Ubuntu Server IP gateway: 192.168.107.1
• Internal DNS Server 1: 192.168.107.212
• Internal DNS Server 2: 192.168.107.213
• External DNS Server 1: 8.8.8.4
• External DNS Server 2: 8.8.8.5
• Ubuntu Admin ID: administrator
• Ubuntu Admin Password: myadminpass
• Nagios Admin Password: mynagiospass
• Nagios NSClient Port #: 12489
• Nagios NRPE Port #: 5666
• Nagios Service Password: myservicepass
• Email Server (remote): 192.168.107.25
• Windows Share ID: myshare
• Windows Share Password: mysharepass

I also assume the reader knows how to use the VI editor. If not, you will need to beef up your skill set or use a different editor in place of it.

[LHammonds]

Analysis and Design

The Ubuntu Server Long-Term Support (LTS) is free but we have the option of buy support and that is the main reason this server was selected.

The largest decision over the configuration of Ubuntu seems to be how the hard drive space is sliced up (partitioned). I lot of my time was spent researching and learning the various options when it comes to the design layout of the storage.

I like to make use of a design that allows for dynamic growth and fine-tuning if need be. I also do not like being caught offguard with a scenario where space is filled up with no immediate option other than deleting files. Long-term life and growth of the system as well as budgeting concerns have to be taken into consideration.

I like to contain the root volume to mainly just static data that won't grow much and push the other folders that are dynamic into their own volumes. In case you don't know, filling up the root volume on a *nix system is a very bad thing and should be avoided at all costs. I also want to configure it where the file systems are not taking up 100% of the logical volume. This will allow me (through automated scripts) to grow the file system as needed and give me some time to add more drives if necessary or shrink other volumes to get more space.

Here are my thoughts on how to slice up the space.

• boot - This will remain static in size. It is also the only space residing outside the Logical Volume Manager (LVM)
• root volume - Operating system and everything else which should remain fairly static.
• swap volume - This will remain static in size. However, if amount of RAM is adjusted, this should be adjusted as well.
• var volume - This is the app/database/log storage and will continue to grow over time.
• srv volume - This will contain the files stored in the Samba share.
• bak volume - This will contain a local backup of the application. So space needs to be around double /var.
• tmp volume - This location will be used for temporary storage. Size should be adjusted to match however it is being used.
• Offsite Storage - This will be handled elsewhere but will be mounted on this server.

My estimated database store will be about 2 GB. However, we will start this server off with a lower number. We will then pretend some event happened such as a popular content site which causes quick growth of the database. This will increase our storage needs and we will go through adjusting the entire system to accommodate a larger storage capacity. This will be a good exercise / documentation for what will eventually need to be done later to handle growth.

To get a good idea of the initial hard drive layout and to understand the process better, here is a graphical representation of the initial design for the server:



These numbers will be used for the initial build of the system:

boot = 200 MB
root = 4 GB
swap = 2 GB
bak = 500 MB
tmp = 500 MB
srv = 500 MB
var = 500 MB

NOTE: When the logical volumes and file systems are initially created, they consume the maximum amount of space allocated so that the logical volume size = file system size. These partition sizes are artificially small for that reason. These will be later modified so that the logical volume will be larger than the file system so that the file system has room to expand when needed.

Important info:
- The /tmp folder is strictly temporary. Each time the server reboots, this folder is deleted and re-created.
- The /bak folder will retain the most recent backup and is considered the "local" copy of the backup.

VMware Virtual Machine Settings

Virtual Manager: VMware vSphere Client 4.1
Virtual Host: VMware ESXi Server 4.1

• Configuration: Custom
• Name: srv-nagios
• Datastore: DS3400-LUN0
• Virtual Machine Version: 7
• Guest Operating System: Linux, Version: Ubuntu Linux (64-bit)
• Number of virtual processors: 1
• Memory Size: 1024 MB
• Number of NICs: 1
• NIC 1: VM Network
• Adapter: E1000, Connect at Power On: Checked
• SCSI controller: LSI Logic Parallel
• Select a Disk: Create a new virtual disk
• Create a Disk: 8 GB, No thin provisioning, No cluster features, Store with the virtual machine
• Advanced Options: Virtual Device Node = SCSI (0:0)
• Remove Floppy Drive
• Mount CD/DVD Drive to Ubuntu ISO (ubuntu-12.04-server-amd64.iso). Make sure CD/DVD is set to Connect at power on
• Set boot options to Force BIOS Setup so you can set CDROM to boot before the Hard Disk

VirtualBox Virtual Machine Settings

Virtual Manager: Oracle VirtualBox 4.1.14
Virtual Host: Windows 7 Ultimate with SP1 (64-bit)

• Name: srv-nagios
• Operating System: Linux
• Version: Ubuntu (64 bit)
• Memory: 1024 MB
• Check - Start-up Disk
  - Create new hard disk
  - VMDK
  - Dynamically allocated
  - Size: 8 GB
• Select srv-nagios and click Settings (CTRL+S)
  - System, Processor, Enable PAE/NX
  - Network, Attached to: Bridged Adapter, Advanced, Adapter Type: Intel PRO/1000 MT Server
  - Storage, IDE Controller, Choose a virtual CD/DVD disk file, ubuntu-12.04-server-amd64.iso

Install PuTTY

The 1st time I installed Ubuntu, I used the console for everything but it was painfully slow to view man (manual) pages and navigating in VI (text editor). However, I found out that PuTTY is a far better solution for your Ubuntu console because it handles the screen draws much faster and allows for scrolling and copying text.

Download the portable edition and run the install...except it doesn't really "install" like a normal program, it simply extracts to a specified folder and will run from that folder even if you put it on a USB stick and carry over to a new computer (requires no install to run and thus leaves a very small footprint on your system)

1. Start PuTTY
2. Type the following and click the Save button:
   Host Name: SRV-Nagios (or the IP such as 192.168.107.21)
   Port: 22
   Connection type: SSH
   Saved Sessions: SRV-Nagios
3. Now all you have to do is double-click on the session and it will connect to your server (when online).

[LHammonds]

Install Ubuntu Server

NOTE: During the setup process throughout this entire document, most commands will require "sudo" as a prefix. However, I will be using "sudo su" to temporarily gain root privileges.

1. Power on the Virtual Machine (VM)
2. Press {ENTER} to accept English
3. Select Install Ubuntu Server {ENTER}
4. Press {ENTER} to accept English
5. Press {ENTER} to accept United States
6. Select No to not detect keyboard layout
7. Press {ENTER} to accept English (US)
8. Press {ENTER} to accept English (US)
9. Type srv-nagios {ENTER} (this is your hostname)
10. Type Administrator, {ENTER} for the full name
11. Press {ENTER} to accept the default of the lowercase name of administrator
12. Type myadminpass, {ENTER}, myadminpass, {ENTER}
13. Select No, {ENTER} to not encrypt your home directory
14. Press {ENTER} to accept detected time zone (America/Chicago)
15. Select Manual {ENTER}
16. Select SCSI3 (0,0,0) (sda) - 8.6 GB VMware Virtual disk {ENTER}
17. Select Yes to create new empty partition table, {ENTER}
18. Select pri/log 8.6 GB FREE SPACE {ENTER}
19. Select Create a new partition {ENTER}
20. Type 200 MB, {ENTER} (NOTE: This will be the /boot partition)
21. Select Primary {ENTER}
22. Select Beginning {ENTER}
23. Select Use as: Ext4 journaling file system {ENTER}
24. Select Ext2 file system {ENTER}
25. Select Mount point: / {ENTER}
26. Select /boot - static files of the boot loader {ENTER}
27. Select Bootable flag: off {ENTER} (NOTE: This toggles it on)
28. Select Done setting up the partition {ENTER}
29. Select Configure the Logical Volume Manager {ENTER}
30. Select Yes to write change to disks and configure LVM, {ENTER}
31. Select Create volume group {ENTER}
32. Type LVG {ENTER}
33. Select /dev/sda free #1 (12684MB; FREE SPACE), {SPACEBAR}, {ENTER}
34. Select Yes to write change to disks and configure LVM, {ENTER}
35. Select Create logical volume {ENTER}
36. Select LVG (8384MB) {ENTER}
37. Type swap {ENTER}
38. Type 2G {ENTER} (NOTE: This is double the amount of RAM)
39. Select Create logical volume {ENTER}
40. Select LVG (6387MB) {ENTER}
41. Type bak {ENTER}
42. Type 500M {ENTER}
43. Select Create logical volume {ENTER}
44. Select LVG (5888MB) {ENTER}
45. Type var {ENTER}
46. Type 500M {ENTER}
47. Select Create logical volume {ENTER}
48. Select LVG (5389MB) {ENTER}
49. Type tmp {ENTER}
50. Type 500M {ENTER}
51. Select Create logical volume {ENTER}
52. Select LVG (4890MB) {ENTER}
53. Type srv {ENTER}
54. Type 500M {ENTER}
55. Select Create logical volume {ENTER}
56. Select LVG (4391MB) {ENTER}
57. Type root {ENTER}
58. Type 4G {ENTER} (we will have a small amount leftover in LVG)
59. Select Finish {ENTER}
60. Select #1 2.0 GB directly under LVM VG LVG, LV swap, {ENTER}
61. Select Use as: do not use {ENTER}
62. Select swap area {ENTER}
63. Select Done setting up the partition {ENTER}
64. Select #1 4.0 GB directly under LVM VG LVG, LV root, {ENTER}
65. Select Use as: do not use {ENTER}
66. Select Ext4 journaling file system {ENTER}
67. Select Mount point: none {ENTER}
68. Select / - the root file system {ENTER}
69. Select Done setting up the partition {ENTER}
70. Select #1 499.1 MB directly under LVM VG LVG, LV bak, {ENTER}
71. Select Use as: do not use {ENTER}
72. Select Ext4 journaling file system {ENTER}
73. Select Mount point: none {ENTER}
74. Select Enter manually {ENTER}
75. Type /bak {ENTER}
76. Select Label: none {ENTER}
77. Type bak {ENTER}
78. Select Done setting up the partition {ENTER}
79. Select #1 499.1 MB directly under LVM VG LVG, LV var, {ENTER}
80. Select Use as: do not use {ENTER}
81. Select Ext4 journaling file system {ENTER}
82. Select Mount point: none {ENTER}
83. Select /var {ENTER}
84. Select Label: none {ENTER}
85. Type var {ENTER}
86. Select Done setting up the partition {ENTER}
87. Select #1 499.1 MB directly under LVM VG LVG, LV tmp, {ENTER}
88. Select Use as: do not use {ENTER}
89. Select Ext4 journaling file system {ENTER}
90. Select Mount point: none {ENTER}
91. Select /tmp {ENTER}
92. Select Label: temp {ENTER}
93. Select Done setting up the partition {ENTER}
94. Select #1 499.1 MB directly under LVM VG LVG, LV srv, {ENTER}
95. Select Use as: do not use {ENTER}
96. Select Ext4 journaling file system {ENTER}
97. Select Mount point: none {ENTER}
98. Select /srv {ENTER}
99. Select Label: srv {ENTER}
100. Select Done setting up the partition {ENTER}
101. Here is what the screen looks like at this point: Partitions
102. Select Finish partitioning and write changes to disk {ENTER}
103. Select Yes to write changes to disk, {ENTER}
104. Press {ENTER} to accept a blank line for the HTTP proxy
105. Select Install security updates automatically, {ENTER}
106. Highlight only OpenSSH server and press {SPACEBAR} to enable, {ENTER} to continue. NOTE: This allows us to use PuTTY after installation to connect to the server.
107. Select Yes, {ENTER} to install GRUB boot loader to the master boot record
108. Installation Complete - from the VM menu, select VM --> Edit Settings and select CD/DVD Drive 1 and change to "Client Device" which will effectively remove the ISO. Now press {ENTER} to reboot.

Initial Configurations

1. At the console login prompt, login with your administrator account (administrator / myadminpass)
2. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
3. Type vi /etc/network/interfaces {ENTER} and change the following: (We need to change the network interface card (NIC) from using DHCP to a static IP)
   From:
   

   iface eth0 inet dhcp

   To:
   

   iface eth0 inet static
   address 192.168.107.21
   netmask 255.255.255.0
   gateway 192.168.107.1
   network 192.168.107.0
   broadcast 192.168.107.255
   dns-nameservers 192.168.107.212 192.168.107.213 8.8.8.4 8.8.8.5
   

   NOTE #1: You may need to manually remove the DHCP record (lease) associated to this Ubuntu server from your DHCP server so the correct IP can be found by other machines on the network. This can be avoided by temporarily configuring the VM Network Adapter connection to be "Host Only Network" instead of "VM Network" so the server is isolated during setup...at least until you reach the testing of the static IP below.
   
   NOTE #2: You might also need to manually add a HOST(A) record to your Windows DNS server (for srv-mysql.mydomain.com and srv-mysql.work.mydomain.com)
4. Restart the network by typing /etc/init.d/networking restart
5. Sanity check! Type ifconfig and make sure the settings are correct. Then type ping www.google.com or similar and see if ping works.
6. Shutdown and power off the server by typing shutdown -P now
7. At this point forward, you can use PuTTY to access the console rather than the console itself for better performance, ability to scroll, etc.
8. In VM menu, select VM --> Snapshot --> Take Snapshot. Give it a name like STEP 1 and description of Ubuntu Server 12.04 LTS, clean install, Static IP: 192.168.107.21 and click OK

Software Configurations

1. Start the Ubuntu server and connect using PuTTY.
2. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
3. At the $ prompt, type aptitude -y install vim-nox for use instead of the built-in VI editor. more info
4. At the $ prompt, type aptitude -y install p7zip-full to install 7-zip archive utility.
5. At the $ prompt, type aptitude -y install sendemail to install a command-line email utility.
6. Change the default shell from dash to bash. Type ls -l /bin/sh to see that it points to /bin/dash. Type dpkg-reconfigure dash and answer No. Type ls -l /bin/sh and it should now be pointing to /bin/bash
7. Remove AppArmor to avoid problems by typing the following:
   

   /etc/init.d/apparmor stop
   /etc/init.d/apparmor teardown
   update-rc.d -f apparmor remove
   aptitude remove apparmor apparmor-utils

8. Type vi /etc/hosts and add your email server:
   

   192.168.107.25    srv-mail

9. Test the ability to send email by typing:
   

   sendemail -f root@myserver -t MyTargetAddress@MyDomain.com -u "This is the Subject" -m "This is the body of the email" -s srv-mail:25

10. Reboot the server by typing reboot

VMware Tools

If you are installing under VMware like me, be sure to install the tools to insure maximum performance in a virtual environment.

1. In the VM toolbar for the VM, click Guest, Install VMware Tools
2. At the Ubuntu prompt, type the following:
   

   
   mkdir /mnt/cdrom
   mount /dev/cdrom /mnt/cdrom
   ls /mnt/cdrom       ( make sure you see a file such as VMwareTools-8.3.2-257589.tar.gz)
   tar zxvf /mnt/cdrom/VMwareTools* -C /tmp/
   cd /tmp/vmware-tools-distrib/
   ./vmware-install.pl -d
   reboot
   

VirtualBox Guest Additions - Installation

If you are installing under VirtualBox, be sure to install the Guest Additions to insure maximum performance in a virtual environmnet.

1. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
2. You need to perform the following commands to fulfill the prerequisites:
   

   
   aptitude update
   aptitude safe-upgrade
   aptitude install dkms
   reboot
   

3. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
4. From the VirtualBox menu, click Devices, Install Guest Additions
5. At the console, type the following:
   

   
   mkdir -p /mnt/cdrom
   mount /dev/cdrom /mnt/cdrom
   /mnt/cdrom/VBoxLinuxAdditions.run
   

6. NOTE: The X Windows System drivers will fail to load because this is a headless server with no GUI (which is OK)
7. To see if the services are running, type /etc/init.d/vboxadd-service status or service vboxadd-service status

VirtualBox Guest Additions - Upgrading

If you upgraded VirtualBox on your host machine, you also need to upgrade the Guest Additions on all your guest operating systems.

Then mount the CDROM and run the installer just like the above. Reboot after it is upgraded.

1. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
2. From the VirtualBox menu, click Devices, Install Guest Additions
3. At the console, type the following:
   

   
   mount /dev/cdrom /mnt/cdrom
   /mnt/cdrom/VBoxLinuxAdditions.run
   reboot
   

VirtualBox Guest Additions - Uninstallation

If you are about to migrate from a VirtualBox host to something like a VMware host, you will need to uninstall VirtualBox's Guest Additions.

1. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
2. Type the following:
   

   
   cd /opt/VBox*
   ./uninstall.sh
   

[LHammonds]

Volume / Disk Management

At this point, each volume is fairly small and the file systems contained in them are taking up all of the volume space. This setup allows no room to expand our file system as needed! We need to change this.

We are going to add an additional hard drive and give that space to the LVM. Then space is going to be given to each volume we are going to grow. However, we are not going to max-out the size of the file system. We are going to leave some head room for expansion later which will give us the necessary time to acquire more storage but allow us to immediately grow the file system to accomodate our immediate needs.

bak volume = 4 GB, file system = 2 GB (2 GB available for growth)
srv volume = 1 GB, file system = 500 MB (500 MB available for growth)
tmp volume = 2 GB, file system = 1 GB (1 GB available for growth)
var volume = 2 GB, file system = 1 GB (1 GB available for growth)

We started off with 2 GB to hold these volumes but now need 9 GB. We means we need at least 7 GB more. Adding a 10 GB hard drive will be enough with a little extra left over. (NOTE: This was an arbitrary number because I mainly want to show you how to add an additional hard drives to the system)

Here is a graphical representation of what needs to be accomplished:



If we were to type df -h right now, we should see something like this:

Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/LVG-root  3.8G  912M  2.7G  26% /
udev                  489M  4.0K  489M   1% /dev
tmpfs                 200M  240K  199M   1% /run
none                  5.0M     0  5.0M   0% /run/lock
none                  498M     0  498M   0% /run/shm
/dev/sda1             179M   25M  145M  15% /boot
/dev/mapper/LVG-bak   473M   23M  427M   5% /bak
/dev/mapper/LVG-var   473M  261M  189M  59% /var
/dev/mapper/LVG-tmp   473M   23M  427M   5% /tmp
/dev/mapper/LVG-srv   473M   23M  427M   5% /srv

Since I am running VMware, adding additional space is a snap. However, I will add it in such a way that Ubuntu will see 1 drive added to the system just as if we were to add a physical drive to a physical server.

1. Shutdown and power off the server by typing shutdown -P now
2. In the vSphere client, right-click the Virtual Machine and choose Edit Settings.
3. On the hardware tab, click the Add button and select Hard Disk. Click Next, choose "Create a new virtual disk", click Next, set the size to 10 GB, click Next, Next, Finish. Click OK to close the settings and allow VMware to process the changes.

Collect information about the newly added drive.

1. Start the Ubuntu server and connect using PuTTY.
2. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
3. Type pvdisplay which should show something similar to this:
   

     --- Physical volume ---
     PV Name               /dev/sda5
     VG Name               LVG
     PV Size               7.81 GiB / not usable 3.00 MiB
     Allocatable           yes
     PE Size               4.00 MiB
     Total PE              1999
     Free PE               94
     Allocated PE          1905
     PV UUID               HbQisN-2jhS-FGGG-t5aF-IuMZ-mEDQ-iQNfwx

   The important bits of info here are the PV Name and VG Name for our existing configuration.
4. Type fdisk -l which should show something similar to this (however I abbreviated it to show just the important parts):
   

   Disk /dev/sda: 8589 MB, 8589934592 bytes
      Device Boot      Start         End      Blocks   Id  System
   /dev/sda1   *        2048      391167      194560   83  Linux
   /dev/sda2          393214    16775167     8190977    5  Extended
   /dev/sda5          393216    16775167     8190976   8e  Linux LVM
   
   
   Disk /dev/sdb:  10.7 GB, 10737418240 bytes
   Disk /dev/sdb doesn't contain a valid partition table

   The important bits of info here is the device path for the new drive which I highlighted in red.

Prepare the first drive (/dev/sdb) to be used by the LVM

Type the following:

fdisk /dev/sdb
n (Create New Partition)
p (Primary Partition)
1 (Partition Number)
{ENTER} (use default for first cylinder)
{ENTER} (use default for last cylinder)
t (Change partition type)
8e (Set to Linux LVM)
p (Preview how the drive will look)
w (Write changes)

If we type fdisk -l, we now see /dev/sdb1 which is a Linux LVM partition.

Type the following to create physical volume:

pvcreate /dev/sdb1

Now add the physical volume to the volume group (LVG) by typing the following:

vgextend LVG /dev/sdb1

Now that the space has been added to the logical volume group called LVG, we can now allocate that space to grow the logical volumes.

To get a list of volume paths to use in the next commands, type lvscan to show your current volumes and their sizes.

Type the following to grow each volume by a specified amount (the number after the plus sign):

lvextend -L+3500M /dev/LVG/bak
lvextend -L+500M /dev/LVG/srv
lvextend -L+1500M /dev/LVG/tmp
lvextend -L+1500M /dev/LVG/var

or you can specify the exact size by excluding the plus sign and specifying the end-result size you want:

lvextend -L4G /dev/LVG/bak
lvextend -L1G /dev/LVG/srv
lvextend -L2G /dev/LVG/tmp
lvextend -L2G /dev/LVG/var

To see the new sizes, type lvscan

The last thing to do now is the actual growth of the file systems. We want to grow the existing file systems but only to the size we mentioned earlier so we do not take up all the space in the volume...we want room to grow in the future so we have time to order and install new drives when needed.

resize2fs /dev/LVG/bak 2G
resize2fs /dev/LVG/tmp 1G
resize2fs /dev/LVG/var 1G

NOTE: The srv file system is already at the desired 500 MB size so no resize was necessary.

If we need to increase space in /var at a later point, we can issue the following command without any downtime (we will automate this in a nifty script later):

resize2fs /dev/LVG/var 1536MB

We could continue to increase this particular file system all the way until we reach the limit of the volume which is 2 GB at the moment.

Remember, df -h will tell you the size of the file system and lvscan will tell you the size of the volumes where the file systems live in.

If we were to type df -h right now, we should see something like this:

Filesystem            Size  Used Avail Use% Mounted on
/dev/mapper/LVG-root  3.8G  912M  2.7G  26% /
udev                  489M  4.0K  489M   1% /dev
tmpfs                 200M  244K  199M   1% /run
none                  5.0M     0  5.0M   0% /run/lock
none                  498M     0  498M   0% /run/shm
/dev/sda1             179M   25M  145M  15% /boot
/dev/mapper/LVG-bak   2.0G   23M  1.9G   2% /bak
/dev/mapper/LVG-var  1004M  261M  692M  28% /var
/dev/mapper/LVG-tmp  1004M   23M  931M   3% /tmp
/dev/mapper/LVG-srv   473M   23M  427M   5% /srv

TIP: If you want to see everything in a specific block size, such as everything showing up in megabytes, you can use df --block-size m

[LHammonds]

Configure Ubuntu for File Sharing

This file sharing section is optional but can be handy if you need to swap files between the Linux server and a Windows machine.

This documentation will utilize this share for passing pre-configured files (configs, scripts, etc.) to make it faster/easier during installation.

1. Start the Ubuntu server and connect using PuTTY.
2. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
3. Install Samba by typing aptitude -y install samba smbfs (NOTE: To share a folder with Windows, you just need the samba package, to connect to a Windows share, you need both samba and smbfs)
4. Type the following commands:
   

   
   cp /etc/samba/smb.conf /etc/samba/smb.conf.bak
   mkdir -p /srv/samba/share
   chown nobody:nogroup /srv/samba/share/
   chmod 0777 /srv/samba/share
   

5. Edit the configuration file by typing vi /etc/samba/smb.conf
6. Change workgroup = WORKGROUP to workgroup = work (you are using the domain alias)
7. Change:
   

   #   security = user

   to:
   

      security = user

8. Add the following section to the end of the file:
   

   [share]
   comment = Ubuntu File Server Share
   path = /srv/samba/share
   browsable = yes
   guest ok = yes
   read only = no
   create mask = 0755

9. Save and exit the file.
10. Restart the samba services to utilize the new configuration by typing:
    

    restart smbd
    restart nmbd

11. You should now be able to click Start --> Run and type \\srv-nagios or \\192.168.107.21 {ENTER} and see an explorer window with a Share folder. Drag-n-drop a file into the Share folder. If it worked, it will not display an error message and you should be able to view it from the server by typing ls -l /srv/samba/share/
12. Shutdown and power off the server by typing shutdown -P now
13. In VM menu, select VM --> Snapshot --> Take Snapshot. Give it a name like STEP 2 and description of Ubuntu Server 12.04 LTS, File share configured, Static IP: 192.168.107.21. The Snapshot Manager should now have a nice hierarchy of snapshots (STEP 1 --> STEP 2 --> You are here)

Configure Windows Remote Mount Point

The remote offsite location is a Windows 2008 server that has a vast amount of hard drive space and currently backs up other servers.

Part of the backup process will be to write files to a mounted folder to a Windows share.

First, let's document the variables for this solution below and highlight them in red throughout the document for easy identification.

The values below are merely samples which you need to change in order to match your environment:

Windows AD Domain Name: work
Windows Server Name: SRV-Backup
Windows Server IP: 192.168.107.218
Windows Share Name: nagios
Windows Physical Share Location: D:\Nagios\
Windows Share ID: myshare
Windows Share Password: mysharepass

Create a share on a Windows 2008 server

1. In Windows Explorer, right-click on the D:\Nagios folder and select Properties
2. Click the Sharing tab
3. Click the Advanced Sharing button
4. Place a checkmark beside Share this folder
5. Change the Share name to nagios
6. Set the Comment to Nagios Backup
7. Click the Permissions button
8. Select Everyone and click the Remove button
9. Click the Add button
10. Type in your share account: work\myshare and click the Check Names button, click OK
11. Place a checkmark for Allow Full Control and click OK, click OK, click OK
12. Create a text file in the root of the shared folder called "online.txt" and you might want to add some text inside saying to never delete this file because it is used (will be) by a backup script. Probably a good idea to make it read-only as well. Example: [B]D:\Nagios\online.txt[B]

Create an NFS mount to the Windows 2008 server

Connecting to a Windows share requires the samba and smbfs packages to be installed. If you do not have them, type aptitude -y install samba smbfs

1. Login with your administrator account. At the $ prompt, temporarily grant yourself super user privilages by typing sudo su {ENTER} and then provide the administrator password (myadminpass).
2. Type the following commands:
   

   
   mkdir -p /mnt/backup
   chown root:root /mnt/backup
   chmod 0755 /mnt/backup
   echo "This file is used to tell if the mount is active or not" > /mnt/backup/offline.txt
   chown root:root /mnt/backup/offline.txt
   chmod 0444 /mnt/backup/offline.txt
   touch /etc/cifspw
   chmod 0600 /etc/cifspw
   echo -e "username=work\\myshare\npassword=mysharepass" >> /etc/cifspw
   

3. Type vi /etc/hosts and add the following line anywhere in the file:
   

   
   192.168.107.218    srv-backup
   

4. At this point, you might want to type ping srv-backup to make sure you typed the right IP address as well as seeing a good response.
5. To mount this system for backups, type the following command:
   

   
   mount -t cifs //srv-backup/nagios /mnt/backup --options nouser,rw,nofail,noatime,noexec,credentials=/etc/cifspw
   

6. To test it, type cp /etc/hosts /mnt/backup/hosts.txt and look on the Windows server and see if the file shows up. Then type rm /mnt/backup/hosts.txt and verify that the file was deleted on the windows server.
7. This would also be a good time to verify that you can see the "online.txt" file that will be used by the backup script. Type ls -l /mnt/backup/*.txt
8. To dismount the windows share, type the following command:
   

   
   umount /mnt/backup
   

The scripts will call a common mount and unmount function to connect to this share only when needed.

However, if you would rather have it mounted all the time (even after a reboot), do the following (but remember to not use the mount/umount functions in the scripts later):

1. Type vi /etc/fstab and add the following line at the bottom of the file:
   

   //srv-backup/mysql    /mnt/backup    cifs nouser,rw,nofail,noatime,noexec,credentials=/etc/cifspw    0    0

2. Type mount -a and if it does not spew out any error messages, it will quietly mount the share.
3. To test it, type cp /etc/hosts /mnt/backup/hosts.txt and look on the Windows server and see if the file shows up. Then type rm /mnt/backup/hosts.txt and verify that the file was deleted on the windows server.
4. If you need to unmount it, simply type umount /mnt/backup and it will remain unmounted until you reboot. To make it permanent, you need to remove the line you added in the /etc/fstab file.

[LHammonds]

Nagios Prerequisites

1. Install the required programs:
   

   
   aptitude -y install build-essential apache2 php5-gd wget wibgd2-xpm libgd2-xpm-dev libapache2-mod-php5
   

2. Type vi /etc/apache2/apache2.conf and add the following line:
   

   
   DirectoryIndex index.html index.php index.cgi
   

3. Restart Apache by typing: /etc/init.d/apache2 restart
4. Create users and groups:
   

   
   mkdir -p /etc/nagios /var/nagios
   groupadd --system --gid 9000 nagios
   groupadd --system --gid 9001 nagcmd
   adduser --system --gid 9000 --home /usr/local/nagios nagios
   usermod --groups nagcmd nagios
   usermod --append --groups nagcmd www-data
   chown nagios:nagios /usr/local/nagios /etc/nagios /var/nagios
   

Build and Install Nagios from Source

• Download Nagios software (NOTE: You can use newer links once new versions become available):
  

  
  cd /usr/local/src
  wget http://prdownloads.sourceforge.net/sourceforge/nagios/nagios-3.4.1.tar.gz
  

• Build and install Nagios Core:
  

  
  tar -xzvf /usr/local/src/nagios-3.4.1.tar.gz
  cd /usr/local/src/nagios
  ./configure --sysconfdir=/etc/nagios --localstatedir=/var/nagios --prefix=/usr/local/nagios --with-nagios-user=nagios --with-nagios-group=nagios --with-command-group=nagcmd --with-mail=/usr/bin/sendemail
  make all
  make install
  make install-init
  make install-config
  make install-commandmode
  

• Edit the commands by typing vi /etc/nagios/objects/commands.cfg to change both sendemail references to match the correct sendemail syntax:
  

  define command{
   command_name    notify-host-by-email
   command_line    /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /usr/bin/sendemail -s srv-mail:25 -f "admin <admin@nagios.server>" -t $CONTACTEMAIL$ -u "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **"
  }
  
  define command{
  command_name    notify-service-by-email
  command_line    /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$" | /usr/bin/sendemail -s srv-mail:25 -f "admin <admin@nagios.server>" -t $CONTACTEMAIL$ -u "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **"
  }

• Save and close commands.cfg
• Edit the contacts by typing vi /etc/nagios/objects/contacts.cfg and change the following:
  

  define contact{
      contact_name     nagiosadmin             ; Short name of user
      use              generic-contact         ; Inherit default values from generic-contact template (defined above)
      alias            John Doe                ; Full name of user
      email            John.Doe@mydomain.com   ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
  }

• Save and close contacts.cfg
• Type the following:
  

  
  cd /usr/local/src/nagios
  make install-webconf
  

• Set the nagiosadmin password to mynagiospassword by typing the following:
  

  
  htpasswd -c /etc/nagios/htpasswd.users nagiosadmin
  /etc/init.d/apache2 reload
  

• Ensure Nagios can execute by typing chmod +x /etc/init.d/nagios (NOTE: On this version of Ubuntu and Nagios, it is already set correctly)
• Type the following to avoid startup problems: (NOTE: This is not documented anywhere, it is just my trial, error and observation)
  

  
  mkdir -p /usr/local/nagios/var/spool/checkresults
  chown nagios:nagios /var/nagios/spool/checkresults
  chown nagios:nagios /var/nagios/spool
  chown nagios:nagios /var/nagios
  

• Ensure Nagios is started whenever the system boots up:
  

  
  /usr/sbin/update-rc.d -f nagios defaults 99
  ln -s /etc/init.d/nagios /etc/rcS.d/S99nagios
  

• Check your Nagios configuration file for errors. Look for errors in red.
  

  /usr/local/nagios/bin/nagios -v /etc/nagios/nagios.cfg

• NOTE TO SELF: I need to generate (and document) an SSL certificate to enable SSL to protect the password during authentication. Self-Signed Certs
• Start Nagios for the 1st time.
  

  /etc/init.d/nagios start

• Access the web-based administration utility at http://192.168.107.21/nagios/ (use nagiosadmin for the ID and mynagiospassword for the password)

NOTE: The Nagios server is now up-and-running but doing absolutely nothing. We need plugins to actually make it do something so we will install a base plugin pack. However, we will eventually need to get other plugins and maybe write our own in order to monitor everything we want.

[LHammonds]

Nagios Plugin Prerequisites

Nagios Plugin Requirements for check_snmp:

perl -MCPAN -e 'install Net::SNMP'
Configure as much as possible automatically? yes
aptitude -y install snmp

Requirements for check_mysql: (NOTE: For my site, this is not necessary because I will run it locally on MySQL server)

aptitude -y install libmysqlclient-dev

Requirements for check_nrpe:

aptitude -y install libssl-dev

Nagios Plugins

Download, build and install Nagios plugins (NOTE: You can use newer links once new versions become available):

cd /usr/local/src
wget http://prdownloads.sourceforge.net/sourceforge/nagiosplug/nagios-plugins-1.4.15.tar.gz
tar xzf /usr/local/src/nagios-plugins-1.4.15.tar.gz
cd /usr/local/src/nagios-plugins-1.4.15
./configure --sysconfdir=/etc/nagios --localstatedir=/var/nagios --with-nagios-user=nagios --with-nagios-group=nagios
make
make install

Download, build and install NRPE plugin

cd /usr/local/src
wget http://prdownloads.sourceforge.net/sourceforge/nagios/nrpe-2.13.tar.gz
tar xzf /usr/local/src/nrpe-2.13.tar.gz
cd /usr/local/src/nrpe-2.13
./configure --sysconfdir=/etc/nagios --libexecdir=/usr/local/nagios/libexec --prefix=/usr/local/nagios --localstatedir=/var/nagios --with-nagios-user=nagios --with-nagios-group=nagios --with-nrpe-user=nagios --with-nrpe-group=nagios --enable-ssl=yes --with-ssl=/usr/bin/openssl --with-ssl-lib=/usr/lib/x86_64-linux-gnu
make all
make install-plugin

Verify that Plugins are Working!

For all the plugins we intend on using, we need to verify they are working before trying to integrate them into Nagios. However, not all plugins will work without first configuring the target to be monitored.

Ping an IP address you know to be active:

/usr/local/nagios/libexec/check_icmp -H 192.168.107.20

Check for an HTTP reply from a web server:

/usr/local/nagios/libexec/check_http -H 192.168.107.20

Check for a response from an HP LaserJet printer:

/usr/local/nagios/libexec/check_hpjd -H 192.168.107.51 -C public

Check the uptime of a router via SNMP:

/usr/local/nagios/libexec/check_snmp -H 192.168.107.1 -C public -o sysUpTime.0

NOTE: For whatever reason, this command hangs on me. Not sure what I did wrong this time but I'll track it down, fix it and update these dox.

Check a MySQL server (if on local host):

/usr/local/nagios/libexec/check_mysql -H 192.168.107.20 -P 3306 -u mysqlid -p mysqlpassword

NOTE: This will fail if you do not configure the MySQL server 1st. However, you might want to run the MySQL command remotely via NRPE instead.

[spynappels]

Howdy!

This is a great How-To. The only suggestion I would have is to make the default position to use sudo rather than "enabling" the root account.By all means explain there is a different way of doing things but as this will be a great resource to people with less understanding, it should stick as closely as possible to the established guidelines for this site.

Please see http://ubuntuforums.org/showthread.php?t=1486138 for a little more info, I think you may be venturing out on thin ice here and the rest of the How-To is excellent, I'd hate to see it get into bother for this.

Kindest regards,
Stefan

[LHammonds]

Howdy!

This is a great How-To. The only suggestion I would have is to make the default position to use sudo rather than "enabling" the root account.By all means explain there is a different way of doing things but as this will be a great resource to people with less understanding, it should stick as closely as possible to the established guidelines for this site.

Please see http://ubuntuforums.org/showthread.php?t=1486138 for a little more info, I think you may be venturing out on thin ice here and the rest of the How-To is excellent, I'd hate to see it get into bother for this.

Kindest regards,
Stefan

I already stated as a NOTE before installing Ubuntu that using the root account was just for the initial setup and recommended to switch back to using sudo once setup is complete. However, I did not document the command...which now has the command listed. The article you linked me to is mainly pointed towards desktop / GUI interfaces and incorrectly using root to fix problems to run the GUI...thus making the normal use of the system as the root user. This is NOT even close to what I am doing with this documentation.

That article also mentions the concern of an "influx of new users" but I'd be willing to bet it is in regard to the desktop usage of Ubuntu. The server crowd is significantly smaller. And the documentation for what I am doing will be even smaller than that. I would be interested to see a show of hands as to how many people are actually setting up their server and following what I have written. Of the niche crowd that would actually read all of this, they would probably only use bits and pieces. But I still don't see how I am using the root account as being a problem...even for production systems. Again, these how-to's that I write are all about the initial setup of a server (which by definition means they are not in "production"). I see no problem with any of these setups eventually becoming production systems.

I seriously doubt the ice is that thin regarding that topic and this thread.

However, if these forums require me to re-write them using sudo for everything, I would simply request that the threads I have created to be deleted and I will post them elsewhere. I have no intention of documenting how I will not be setting up a server. If someone would like to make a copy and re-write it using sudo for everything, they can be my guest. I'm just not interested in doing it that way and feel it would be a waste of my time.

LHammonds

[spynappels]

I'm sorry my (well meant) comments seem to have upset you, I was saying that it is an excellent how-to, and was simply offering a suggestion as to how it could be done in a way that most matches the recommended setup according to the article I linked to.

A rewrite is not required, I was suggesting an alternative which did not require setting up a root password,

sudo su

instead of

su root

Anyway, enjoy using Linux, it is always good to have more than one way of doing things.