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.


What is my password for the cmpt 471 Virtual network?

You will login with Your SFU campus account to the VNL Gateway (see instuction's email for hostname to use) assigned to you. Once you logged in to the VNL Gateway, access to any host in the Virtual Network Lab is via passwordless authentication with a pair of private/public keys preset on your home directory on the gateway (~/.ssh) .   DO NOT remove the files under ~/.ssh or your won't be able to login to VNL hosts. 

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Can users in CSIL connect to the Virtual Network?

Yes.

Users can connect to the Virtual Network from any CSIL workstations.

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Can users connect to the Virtual Network outside CSIL?

Yes. You can connect to the Virtual Netowrk via one of the VNL gateway (e.g. cs-vnl-01.csil.sfu.ca)  that's assigned to you via RDP or ssh (port 24).   Please refer to the email from instructor for the hostname of the VNL gateway assigned to you.

RDP Access

xRDP server is running on the VNL gateway to provide full remote desktop access to the VNL lab.  Remote Desktop Client (mstsc) is natively available on any Windows workstation.    Most Linux come with rdesktop client.  

SSH Access

The users may also ssh to the Virtual Network if they have an appropriate ssh client - we have SSH client installed on all Windows workstations in CSIL; for your own computer, you may use client like PuTTY). Most distors of Linux come with an ssh client package installed. The command is:

ssh -p 24 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 -p 24 cs-vnl-01.csil.sfu.ca

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I've connected to VNL gateway. Now what do I do?

Once you are connected to your assigned VNL Gateway,  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 username.  (Note: sudo is not permitted on the routers)

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What is vSphere Client?

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 a web interface.  The web interface we use in the CSIL Virtual Network Lab to access virtual machine consoles is this VMware vSphere Client.  

You can access the vSphere Client via https://cs-lab-01.csil.sfu.ca/ui   Login with the following:

Username: <username>@sfu.ca

Password: <SFU campus password>

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How to use vSphere Client?

After successfully login to vSphere Client,  at the pull down Menu

  • go to the VMs and Templates view.
  • In the left hand side pane,
  • click on the > icon beside cs-lab-01.csil.sfu.ca, then again on the TASC1-8206, and then on the CS-VNL
  • now, select one of VNL which you are instructed to use for assignment.  A list of the VMs running inside the vApp are listed on the right pane under the VMs tab.

Double click on the VM to open the summary on the right pane, click on the "Launch Web Console" to access the virtual console fo the VM.   Right click on a VM will provide options to Reset the VM or to Revert back to lastest snapshot 

Working with the vSphere client

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:

  • What you type on the console is seen by others connecting to the console
  • 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.

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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.

To access a virtual machine's console for the VNL, you need to use the connect to the vSphere Client

Within the vSphere Client, you may work on the virtual machines just like physical machines.

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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 Client, right click on the broken machine select

    Power -> power off

  • right click on the broken machine, select

    Snapshots -> Revert to latest snapshot 

  • make sure to power on the VM after reverting to the snapshot.

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Running GUI Programs Remotely

  1. Connect to cs-vnl-01.csil.sfu.ca with RDP 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.

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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/username

  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

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Last updated @2018.05.10