CMPT 471 (Networking) Frequently Asked Questions

What's the Virtual network?

The Virtual Network exists only as a set of virtual machines on a virtual network topology. There are no physical switches, wiring or workstations. A group of machines in the ASB 9700 Lab (the colourless ThinStation machines in the CSIL Burnaby layout (PDF)) can be booted so as to allow the user to connect to the Virtual Network Console - and from there interact with the rest of the Virtual Network's devices.

Note: if you don't get the menu options on a ThinStation, please simply power cycle the machine and select Virtual.Network.Lab

What is my initial password for the cmpt 471 Virtual network?

Your SFU campus account will not work in the Network Lab. This is because both the 471 Lab Virtual Network machines are not part of the campus Active Directory domain, and so cannot use the campus authentication services. We have set up an account and password for each student on the my.sfu.ca site:

1. Login to the CS Portal
2. Your VNL Password is listed under CMPT 471 Information

Can users in CSIL connect to the Virtual Network?

Yes. Users can connect to the Virtual Network from any of the Thinstations in ASB9700.

Can users connect to the Virtual Network outside CSIL?

Yes. You can connect to the Virtual Netowrk via cs-vnl-01.csil.sfu.ca using NX Client or ssh.

NX Client Access

If you are logged on to a Linux, Window or Mac OS X workstation outside CSIL, then you can use NX Client to connect to cs-vnl.csil.sfu.ca. NX client for different OS can be downloaded from here

Windows users may also ssh to the Virtual Network if they have an appropriate ssh client (like PuTTY) installed on their machine. Most versions of Linux come with an ssh client package installed. The command is:

ssh cs-vnl-01.csil.sfu.ca

If you are logged on to a Linux or Mac OS X workstation outside CSIL, then you can start a terminal session, and use ssh to connect. At the command prompt, enter:

ssh cs-vnl-01.csil.sfu.ca

I've connected to cs-vnl.csil.sfu.ca. Now what do I do?

Once you are connected to cs-vnl.csil.sfu.ca, you can ssh to any machine on the Virtual Network. The virtual machines names are:

spring
summer
autumn
fall
winter

equinox
solstice
year
january
february

march
april
may
june
july

august
september
october
november
december

If you now connect to one of the above virtual machines with:

ssh -Y {hostname}

and once you're logged in, type:

sudo sh

you now have two options for your course assignments. You can either stay in the shell you started just now with the sudo command (all commands in this shell will run with root privileges) or exit this shell to run commands under your own userid.

I can't ssh to a machine in the VNL from cs-vnl-01.csil.sfu.ca. What's wrong, and how can I fix this?

Virtual machines are pretty much the same as real physical computers, in that they sometimes suffer from the same software misconfiguration problems (e.g. firewall/routing table change errors) as real machines can. Virtual machines can "hang" from software errors and become unresponsive to the point that the only thing you can do is re-boot them. Make sure that the machine in question is truly hung. You may be able to simply kill off some process/application program that is malfunctioning. See the unix/Linux kill and ps man pages for details.

The biggest difference with a virtual machine is that instead of physically going to the unresponsive physical machine and working at the console (and possibly turning it off and back on), you have to access a virtual machine's console via software. The software we use in the CSIL Virtual Network Lab to access virtual machine consoles is the VMware vSphere Client (Windows only). There are 3 ways to connect to our VMWare server:

1. From a general CSIL Windows machine, go to: Start -> All Programs -> CMPT-471 -> CS-Lab Console
2. From the CSIL Windows Terminal Server, go to: Start -> All Programs -> CMPT-471 -> CS-Lab Console
3. From your own Windows based machine, install the CS Lab Console for vSphere by installing the CS Lab Console.

No matter which one you choose, when you connect, you will be prompted for your login in order to connect to the CS Lab Console Server. Accept any challenges for unrecognized security certificates. Use your SFU ID and password; the vSphere Client should start automatically, and you will have to authenticate again. Accept the second security certificate, and the vSphere Client should start.

Go to the VMs and Templates view. In the left hand side pane, click on the + icon beside the folder, cs-lab.cmpt.sfu.ca, then again on the CSIL folder, and finally on the VNL folder. You will now be presented with a list of the virtual machines that are being hosted on the cs-lab.cmpt.sfu.ca host machine (this server is also a virtual machine). By clicking on your desired machine in the left pane and clicking the Console tab on the right pane, you can then access that machine's Virtual Console.

Working with the vSphere console

For the most part, a virtual machine works just like a real physical computer, with the console simply displaying what's on the virtual screen. A few notes:

• When a virtual machine "captures" the cursor, you can release it by pressing the Ctrl and Alt keys simultaneously.
• To force the machine to reset, select VM -> Power -> Reset
• The vSphere Console should only be used for restarting virtual machines when they can't be accessed, when there is no other option. Remember that bringing down and restarting virtual machines can negatively affect other users who may be logged into those virtual machines. Please be responsible with this feature, and treat other users with respect.
• If you change some permanent feature of the operating system, you may not be able to recover it by restarting the virtual machine. See the question and answer below for details.

I restarted the virtual machine, but something is still wrong with it. What do I do?

If you cannot connect to a virtual machine you just restarted, or even after restarting it is not operating normally, then it is likely that you made a change to the system that is unrecoverable/unfixable.

This can happen because most users in the Network Lab operate as the root user. This account is dangerous because with it you can do pretty much anything you want on the system. Unfortunately, this can include the deletion/alteration of critical operating system files, which can leave the virtual machine inoperable. To reset a broken virtual machine to its original working state:

• From the vSphere console, right click on the broken machine selecting

  power off

  .
• Right click on the broken machine, select

  snapshot -> revert to current snapshot

  and make sure the new machine is powered up.

Running GUI Programs Remotely

1. Connect to cs-vnl-01.csil.sfu.ca with NX client
2. ssh to a machine on the Virtual Network (e.g. july):
   
   

   ssh -Y july

   the -Y option allows the X display of GUI-based programs (like wireshark) to be sent back to cs-vnl-01
   
   
3. Become the effective root user:
   
   

   sudo sh
   

4. run your GUI-based program (eg. wireshark) as effective root user. The graphical output should go to your X session on cs-vnl-01.

Retrieving files from a remote Network Lab computer to your computer outside CSIL

1. from your computer, ssh to cs-vnl-01.csil.sfu.ca
2. from cs-vnl-01, sftp to your target Network Lab machine (e.g. july) where the files you want to transfer have been saved
3. transfer your files to your account on cs-vnl-01
4. disconnect from your Network Lab machine
5. log out of cs-vnl-01
6. from your computer, sftp to cs-vnl and transfer your files to your computer

You may also use scp to transfer files:

1. from your target Network Lab machine:
   
   

   scp {filename(s)} cs-vnl-01:/home/{userid}

2. disconnect from your Network Lab machine
3. log out of cs-vnl-01
4. from your computer, sftp to cs-vnl-01 and transfer your files to your computer

How can I print from the 471 network?

Since there is no printer attached to the Virtual Network, you must access a printer that is outside your immediate network. This means using the printer on the CSIL Network.

If you are logged on to a Linux machine on the Virtual Network:

1. Transfer your files to the server, cs-vnl-01.csil.sfu.ca, which is connected to both the Virtual Network and the CSIL Network :

   scp {your filename(s)} {yourid}@cs-vnl-01.csil.sfu.ca:/home/{yourid}

2. Login (via ssh) to cs-vnl-01.csil.sfu.ca, then print your files to the CSIL printer:

   lp {your filename(s)}

Do I need a print card for printing?

Yes, same as any other print job in CSIL.