OPS235 Lab 6 - Fedora17

Configuring a Network Using Virtual Machines

Caution!
This lab is very much under construction. Please do not start it until this warning is removed.

Objectives

• Configure a virtual network for Virtual Machines
• Use the Fedora GUI program to configure network interfaces with static IP configuration and host name resolution
• Use the find command to locate the configuration files modified by the GUI network configuration program
• To examine some of the Linux's TCP/IP configuration files in the /etc/ directory
• To configure a Fedora host with static network configuration without a GUI tool
• To use and interpret the netstat command to troubleshoot and monitor network services
• To configure the linux firewall iptables to allow/disallow/forward different types of network traffic using simple rules

Reference

• man pages for find, ifconfig, ping, netstat, NetworkManager, nslookup, iptables, arp
• Online reading material for week 8.

Required materials

• Fedora 12 Live CD or a classmate on the same pod
• USB flash drive, 64 MB or more in size (Warning: the contents of this drive will be erased)
• One SATA hard disk in a removable drive tray with Fedora host and 3 Fedora Virtual Machines installed

Current Configuration

Currently you should have the following network configuration:

• Fedora host has 1 active network interface (probably eth0)that receives IP configuration from the School's DHCP server.
• Fedora host has 1 active network interface (virbr0) that has a static default configuration of 192.168.122.1/255.255.255.0
• Fedora1 VM has 1 active interface (eth0) that receives a dynamic configuration from your Fedora Host
• Fedora2 VM has 1 active interface (eth0) that receives a dynamic configuration from your Fedora Host
• Fedora3 VM has 1 active interface (eth0) that receives a dynamic configuration from your Fedora Host

Lab Preparation

Important
It is advisable to perform a yum update on your Fedora host and all 3 VM's.

Important
The fedora1 VM was installed from Live CD. It is missing the GUI Network Configuration tool we will be using. Use the command yum install system-config-network to install it.

Important We will be working with your 3 VM's
Backup your VM disk images and then stop all 3 VM's for until told to start them.

Lab Investigations

Investigation 1: How do you create a new virtual network.

Note!
Complete this investigation on your fedora host.

Before configuring our network we want to turn off dynamic network configuration for our Virtual Machines by turning off the "default" virtual network.

1. On the fedora host start Virtual Machine Manager
2. Under Edit->Host Details select the Virtual Networks tab
3. Disable the default configuration from starting at boot by deselecting the "Autostart On Boot" checkbox.
4. Stop the default network configuration by clicking on the stop button at the bottom of the window.
5. Click on the add button to add a new network configuration.
6. Give your new network a name (network1)
7. Enter in the new network IP address space:
   • 192.168.235.0/24
8. Disable DHCP by deselecting the check box.
9. Enable Network Forwarding by Selecting "Forwarding to physical network"
10. The destination should be "Any physical device" and the mode should be "NAT"
11. Now we need to add our new virtual network "network1" to the 3 VM's
    1. Select the fedora1 VM and edit the VM details
    2. Under View select Details
    3. In the left pane select the NIC and note that this NIC is on the "default" virtual network
    4. Click on the Remove button
    5. Click on "Add Hardware" and add a new network
    6. For the host device select "Virtual Network network1" : NAT
12. Repeat these steps for fedora2 and fedora3 VM's
13. Answer the Investigation 1 question in your lab log book.

Investigation 2: How do you configure a static network using system-config-network.

Note!
Complete this investigation on your fedora2 VM.

1. Start fedora2 VM and login
2. On your fedora host run ifconfig and make note of the IP address assigned to the virbr1 interface. This will be your default gateway for your Vm's.
3. To configure a new interface on fedora2 go to System->Administration->Network and click on the "New" button
4. Select Ethernet Device and choose the network card named eth1
5. Statically set the IP configuration:
   • IP Address 192.168.235.12
   • Subnet Mask 255.255.255.0
   • Default Gateway 192.168.235.1 (The IP address of virbr1 on your fedora host.)
6. Click on the DNS tab and add 192.168.235.1 as the primary DNS server.
7. Save then Quit
8. Restart your network on fedora2. service NetworkManager restart
9. Verify your new interface by examining the output of ifconfig
10. To verify that fedora2 has the correct default gateway configured, enter the command route -n
11. Verify the network by using ping 192.168.235.1
12. Record the answer to Investigation 2 in your logbook.

Investigation 3: What files does the system-config-network GUI tool change?.

Note!
Complete this investigation on your fedora1 VM.

1. Start fedora1 VM and login
2. Before we configure fedora1 we should create a timestamp file that can be used to see which files have changed as a result of using the GUI tool.
   • date > /tmp/timestamp
3. Run the network configuration tool and enter the following static configuration in the same way that you configured fedora2.
   • IP Address: 192.168.235.11
   • Subnetmask: 255.255.255.0
   • Default Gateway: 192.168.235.1
   • DNS Server: 192.168.235.1
4. Save and quit and restart NetworkManager
5. Verify the configuration by pinging fedora host (192.168.235.1) and fedora2 (192.168.235.12)
6. To verify that fedora1 has the correct default gateway configured, enter the command route -n
7. Use the find command to locate the configuration files modified by the GUI network configuration program
   • Previously, you created a file called /tmp/timestamp. Any files that were modified by the GUI network configuration program should have a timestamp later (or newer) than the "timestamp" file you created. All the Linux TCP/IP configuration files are stored under the "/etc" directory or its sub-directories. The following command when run as root will give you a list of all the files under the /etc directory with a file modification date newer than the date of the "timestamp" file:
     • find /etc -newer /tmp/timestamp
8. Capture the output to a file called netcfg.lst under user root's home directory.
9. Create a new directory called /tmp/lab6 and copy all the files from the find command to it.
   • There are a number of ways to accomplish this:
     • Edit netcfg.lst and turn it into a bash script.
     • Copy the files manually using the cp command.
     • Investigate the -exec option of the find command to see how to find and copy the files with a single command.
10. Record the answer to the investigation in your lab log.

Investigation 4: How do I configure the network without a GUI tool?.

Note!
Complete this investigation on your fedora3 VM.

1. Start fedora3 VM and login as root
2. Use the command ifconfig to list active interfaces, you should see one with a name of eth1 or a similar name.
3. To configure your card with a static address use the command:
   • ifconfig eth1 192.168.235.13 netmask 255.255.255.0
4. To configure a default gateway for that interface enter the command:
   • route add default gw 192.168.235.1
5. To configure your DNS server edit the file /etc/resolv.conf. Change the nameserver line to be:
   • nameserver 192.168.235.1
6. Confirm your settings work by doing the following:
   • ifconfig
   • route -n
   • ping your other VM's and fedora host.
   • ssh to your matrix account to test DNS
7. Restart the fedora3 VM
8. Login and test your configuration again. What happened?
9. While we can configure network settings from the command line those settings are not persistent. To configure persistent network configurations we need to edit the configuration files:
   • Change to the /etc/sysconfig/network-scripts directory on fedora3
   • List the contents of the directory and you should see 2 different types of files, network config scripts and network configuration files.
   • look for the config file for your original interface, it should be named ifcfg-eth0
   • Copy that file to ifcfg-eth1 or whatever name matches your current eth interface.
   • Edit the new file for you interface and give it the following settings:
     • GATEWAY=192.168.235.1
     • DNS1=192.168.235.1
     • DEVICE=eth1 <-- or the interface name you have
     • BOOTPROTO=none
     • NETMASK=255.255.255.0
     • TYPE=Ethernet
     • HWADDR=52:54:00:3f:5c:fa <--use the HWADDR for your interface
     • IPADDR=192.168.235.13
     • IPV6INIT=no
     • ONBOOT=yes
     • USERCTL=no