Network Security Fundamentals

This page contains course information for students taking the Network Security Fundamentals course, offered in April, 2013 through Merit. This information will be available before and during the course.

Hints and Tips

• VMware Tools

If cut/paste into or out of the virtual lab environment's window doesn't seem to work, or the desktop wallpaper doesn't redraw to fill the window after you resize it, check to see if the vmware-user-loader is running in your guest:
$ ps ax | grep vmware-user-loader
If this command returns no output, try one or more of these:

1. Manually start /usr/bin/vmware-user
2. Log out and log back into your desktop session; and,
3. Restart your X session.
• Screensaver timeout

  To lengthen your virtual lab environment's screensaver timeout, visit System | Preferences | Screensaver and adjust the "Regard the computer as idle after" value.

• Screen resolution

  To increase the virtual lab environment's screen resolution from 1024x768, it's easiest to drag its containing window to the size you want. If the window won't resize, use the following procedure:

  1. Determine the resolution you'd like to use, up to the maximum resolution of your display.
  2. Shut down your VMware guest virtual lab environment.
  3. Add the following line to the end of your .vmx file:
     svga.maxHeight = "NNN"
     where NNN is the maximum resolution height you'd like to use. For example, if your desired resolution is 1440x900, you'd put 1440 here.
  4. Bring up your virtual lab environment, log in, and change your guest's maximum resolution by visiting System | Preferences | Displays and changing to your specified resolution.

• Default terminal window attributes

  To change terminal default attributes such as the window size or the character size:

  1. Start a terminal window (by selecting Applications | System Tools | Terminal).
  2. Select Edit | Profiles... from the terminal window menubar.
  3. Click Edit to edit the default terminal profile.
  4. In the profile editing window popup, under the General tab, to change the default text size, uncheck the "Use the system fixed width font" checkbox, then select the Monospace font and the desired point size.
  5. Similarly, to change the default terminal window size, check the "Use custom default terminal size" checkbox and set the desired number of rows and columns.
  6. Click Close twice to close both popups.
• NAT vs. Bridged VMware guest

  As shipped, the virtual lab environment shares your host platform's network connection by using a NAT service running on your host platform. While this is the most scalable and unobtrusive way to run a VMware guest, some operations will not work as expected, such as traceroute commands. To switch your guest over to bridged mode, in which it obtains a network address via DHCP directly from the same network provider that your host platform uses, follow these steps:

  1. Click on the <...> symbol in the lower right hand corner of your guest's screen, or look under Network Adapter in your host's Settings or VM | Settings menu.
  2. Select the Bridged option.
  3. Wait until your host has indicated the network has been reconnected to your guest.
  4. Restart the network in your guest, either through the GUI or by typing:
     sudo service network restart

• Add a CDROM device

  To define a CDROM device for your virtual lab environment:

  1. Shut down your VMware guest virtual lab environment.
  2. Replace the following line of your .vmx file
     ide0:0.present = "FALSE"
     with
     ide0:0.present = "TRUE"
     ide0:0.autodetect = "TRUE"
     ide0:0.deviceType = "cdrom-raw"
     Note: your CDROM drive may appear at ideN, N != 0; adjust the above directives accordingly.
  3. Bring up your virtual lab environment.

• Boot into the BIOS

  To enter the VMware guest's BIOS, say for changing boot devices, you'll need to hit F2 at the right time during boot. This is often difficult to do reliably, so use the following strategy instead:

  1. Add the following line to the end of your .vmx file:
     bios.forceSetupOnce = "TRUE"
  2. Boot up your virtual lab environment. You'll see a conventional BIOS screen, from which you can make BIOS-level changes and boot your guest.
     Note: VMware will change the value of this option to FALSE in your .vmx file after a successful boot. This means you'll need to re-enable this trigger each time you want to use it.

• Change password hashing algorithm

  To change your virtual lab environment's password hashing algorithm from SHA512 to MD5, change the string "sha512" to "md5" in /etc/pam.d/system-auth. Any passwords you set or modify after this change has been made will use the new hashing algorithm; existing password hashes are not affected.
  Note: MD5 is a weaker hashing algorithm than SHA-512 and should not be used except in designated experiments in this course.

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