OPS335 NFS Lab

NFS RESOURCES

Online References:

• File Server Notes (Week 9 class notes)
• NSF Security (List of tips regarding NSF and security)

OVERVIEW

In OPS235, you learned how to install and configure an SSH server to be able to use utilities such as ssh, scp and sftp. Although the sftp utility is useful for transferring files between different computers via the Internet, it is not considered useful or efficient for accessing files on servers that are connected over a local network.

Two popular protocols called Network File Server (NFS) and Samba (SMB) are used to provide high speed file access between servers on a local network. The NFS protocol allows a user to access files on another server in a local network in a similar way that local files on a same server are accessed. The Samba open-source software is used to access files from Windows servers using a combination of Windows protocols including NetBIOS, SMB, etc., and will be discussed in the next lab.

This lab will focus on installing, configuring and using NFS to access files between different Linux servers on your local network.

INVESTIGATION 1: USING AUTOMOUNT WITH NFS

In this investigation, we will set up an NFS server on our VM2 machine. We will then set up an NFS client on our VM3 machine so that we can view and import files of VM2's /home directory from our VM3 machine.

Prerequistites
Due to the changes made in lab3, you will now need your vm1 running (as the DNS server) in order for any of your virtual machines to be able to use the internet.

Setting up the NFS Server (VM2)

Perform the following tasks:

1. Make certain that all of your VMs are running.
2. Switch to your VM2 machine.
3. Although the NFS application was already installed on your VM, we will install additional utilities for NFS by issuing the following command:
   yum install nfs-utils
4. The /etc/exports file allows you to restrict the access to servers to access files for security purposes. Edit the /etc/exports file, and add the following line to the file:
   /home 192.168.x.4(rw,root_squash,insecure)
5. What does the IPADDR 192.168.x.4 represent? Record your answer in your lab logbook.
6. Issue the following command (in order of appearance) in order to start your NFS server:
   systemctl start rpcbind
   systemctl start nfs
7. Use the systemctl command to enable both the rpcbind and nfs services upon VM startup.
8. Issue the following command in order to add (or "build") the server's list of permitted exports:
   exportfs -r
9. Run and record the output of the following commands in your lab logbook:
   exportfs
   showmount -e
10. You will have to adjust your firewall settings on your VM2 machine to allow NFS to work (Tip: run the netstat command in order to determine the ports needed and issue the appropriate iptables command or commands).

Setting up & Testing the NFS Client (VM3)

Perform the following tasks:

1. make certain that your VM3 machine can connect to the network and that your VM1 machine is running as the DNS server (Tip: you can use the "host cbc.ca" command to see if DNS queries are being answered.
2. Since the nfs package was installed when you cloned the machine, you are not required to install the nfs or nfs-utils package.
3. Add the following line to the bottom of the /etc/fstab file on your VM3 machine:
   192.168.x.3:/home /home nfs4 defaults 0 0

Warning: Do not change any other lines in this file.
Do not change any lines in /etc/fstab file contained for your VM3 machine. Doing so can cause your VM3 machine not to boot properly.

5. Run the following command to confirm that SELinux will not block the network share:
   setsebool -P use_nfs_home_dirs 1
6. Issue the following command to mount any network shares without having to logout and login to your VM3:
   mount -a
7. Create an empty file within the regular user's home directory on your VM3 machine. Switch to your VM2 machine and view the contents on your regular user's home directory. What you do you notice? what does this mean in terms of using NFS? Record your observations in your lab logbook.
8. Restart your VM3 machine and login with your regular user id.
9. Check that the home directory is mounted:
   mount | grep /home
10. If it is not, try running 'mount /home' as root and observe any errors.
11. Create another file in the regular user's home directory on your VM3 machine.
12. Switch to your VM2 machine to see if you can view that file.
13. Finally, switch to your VM3 machine and shutdown this machine. Finally, switch to your NFS server (VM2 machine) and issue the ls -l command in the regular user's home directory to check if you can still view and access that file that was created in your VM3 machine. If not, what is the reason why you cannot view or access the file? Record your answer in your lab logbook.

Record steps, commands, and your observations in INVESTIGATION 1 in your OPS335 lab log-book

INVESTIGATION 2: SETTING UP AUTO-MOUNT ON CLIENT (VM3)

x

Perform the following tasks:

1. Switch to your VM3 machine.
2. Comment or remove the line from /etc/fstab that you entered earlier.
3. With a server installation of Fedora 22, you will not need to install autofs, but on other installations you might need:
   dnf install autofs
4. Move the existing file /etc/auto.master:
   mv /etc/auto.master /etc/auto.master.orig
5. This is a great way to keep a back up in case you need to restore the file in the future. Now create another:
   vi /etc/auto.master
6. Add only the following line:
   /home /etc/auto.home --timeout=60
7. Create the file /etc/auto.home and add ONLY the following line:
   * -fstype=nfs4,rw,nosuid,soft 192.168.x.3:/home/&
8. Start autofs, and ensure the service will automatically start at boot.
9. Log out of vm3 and log back in using your learn account.
10. Open a terminal and enter the command:
    mount | grep home
11. How does it differ from the previous mount?
12. Create another empty file with the name:
    touch another_empty_file_from_vm03
13. Run and record the output of the command:
    df -hT
14. Back on the nfs server run and record the output of ls -l in your home directory.
15. You should see the files you created on vm03.
16. You may encounter errors with SELinux during the lab (though it has not been a problem recently). It is required that you leave it running. #Use the following commands to determine what booleans need to be flipped:
    audit2allow < /var/log/audit/audit.log
    audit2why < /var/log/audit/audit.log
17. Now that you have VM3 automatically mounting home directories from VM2, configure VM1 to do the same.

Record steps, commands, and your observations in INVESTIGATION 2 in your OPS335 lab log-book

COMPLETING THE LAB

Arrange proof that ...

EXPLORATION QUESTIONS

1. What does the no_root_squash option for an NFS mount mean?
2. Explain the meaning of the defaults option in an fstab entry. What do the numbers mean at the end?
3. What is the function of the 'exportfs' command?
4. What is the purpose of the 'showmount' command?
5. What is the meaning of the "timeout=60" phrase?
6. What is the meaning of the asterisk (*) in the file /etc/auto.home?
7. What is the meaning of the ampersand (&) in the file /etc/auto.home?
8. What is the role of the /etc/mtab file on the nfs server?
9. What port does nfs-server use?
10. What is the purpose of the testparm command?
11. What does SMB stand for? CIFS?