Networking

CT320: Network and Systems Administration                 

Purpose

The purpose of this assignment is to experiment with the setup of networking and network-based programs.                 

Part 1 — Clean Up

Make sure that your system has a manually configured IP address, as described in the configuration lab.                 

Part 2 — Test Networking

Make sure you can access the Internet and Domain Name Service (DNS) with these commands:                 

    dig google.com
    wget -qO- https://www.cs.colostate.edu/~ct320/alphabet.txt

If they don’t work, fix things.                 

Part 3 — Network File System (NFS)

Installation

Install the NFS server package:                 

    sudo apt install nfs-kernel-server

Server

• Create a directory /export and populate it with several directories and files.
• Export the file system by adding an entry to /etc/exports, like this:

    /export ip-address-of-neighbor(rw)

• Make sure that the appropriate daemons are running and document their names.
• Restart the NFS service:

    sudo systemctl restart nfs-server

• Verify that your neighbors can access the exported file system.
• Alter the /etc/exports line to look like this:

    /export not-the-ip-address-of-neighbor(rw)

• Restart the NFS service.
• Verify that your neighbor cannot mount the driver, then restore access.

Client

• Create a directory with the path name /import
• Mount /export from their system to yours:

    mount ip-address:/export /import

• Make sure you can browse the imported file system.
• Add an entry to /etc/fstab to automate the mounting of your neighbor’s exported file system.
• Reboot and verify that you still have access to their files. At this point you should be able to access your neighbor’s exported file system and they should be able access to yours.

Part 4 — Secure Shell (SSH)

• Make sure that the sshd daemon is installed on your neighbor’s computer:

    sudo apt install openssh-server

• Use the ssh command to gain access to the ct320 account on your neighbor system and have them do the same.

    ssh neighbor-ip-address hostname

• Get out of ssh by typing exit.
  • Don’t expect a name like ct320-1 to work, since we have no DNS server or /etc/hosts translating those names into IP addresses.
• Use the scp command to copy files between the systems, in each direction (push & pull).
• Create the file /etc/ssh-warning that contains a message telling users to behave themselves.
• Use the Banner directive in the sshd config file to display /etc/ssh-warning to remote users, restart sshd, and show that it works.
• Is ssh access equivalent functionality to the NFS exercise in Part 3?
• What are the advantages or disadvantages or each method?
• How can you control ssh access, without disabling the sshd daemon?

Part 5 — Dynamic Host Configuration Protocol (DHCP)

See https://askubuntu.com/questions/140126/how-do-i-install-and-configure-a-dhcp-server                 

This is a group exercise for the entire recitation.                 

• Install the DHCP server on one system in the lab using this command: sudo apt install isc-dhcp-server
• Edit /etc/default/isc-dhcp-server and set INTERFACES="eno0"
  • The name of the interface varies—it may be eno0, or sometimes eth0.
  • The first line of the ip route command should show your gateway and interface name.
• Configure that DHCP server to allocate addresses starting with 192.168.110.85.
• Comment out all the existing lines in /etc/dhcp/dhcpd.conf using # and edit the configuration file as follows:

    subnet 192.168.110.0 netmask 255.255.255.0 {
        range 192.168.110.85 192.168.110.99; #the range of IP addresses that will be assigned
        option routers 192.168.110.1; #the default gateway
        option domain-name-servers 129.82.45.181; #the DNS server
        option subnet-mask 255.255.255.0;
    }

• Restart the DHCP server using this command: sudo service isc-dhcp-server restart
• Bring up the DHCP server on this system
• On all the other systems, configure to use DHCP.
• Reboot all the other systems.
• Observe that an address of the form 192.168.110.85–99 is obtained.
• Restore the systems to their original static IP addresses
• Disable the DHCP server.

Part 6 — Credit

Show your work to the TA for credit.                 

Part 7 — Clean Up Again

• Restore /etc/fstab to its state before the lab.
• Restore /etc/exports to its state before the lab.
• sudo apt remove openssh-server nfs-kernel-server