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Tamper-Proofing Public Computers |
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An Experiment In Tamper-Proofing Public Computers At An Internet Café.
The challenge at Coffeetopia was deceptively simple: using only free software, figure out a way to make the 7 public internet computers tamper-proof.
The following criteria needed to be met:
• Computers should reset to a default state when rebooted.
• The default state should be easily updateable on all computers.
I used the following tools to accomplish this:
• VMWare ESXi server
• Ubuntu Linux 8.10
• PuTTy and plink
The process flows something like this:
On startup:
1. Computer boots into Linux
2. Linux VMWare server loads a Windows XP image into fullscreen.
3. Café user interacts with Windows XP image
On shutdown:
1. Windows Group policy calls a script when Windows shutdown command is issued
2. Script calls plink, which calls puTTy to ssh into the host Linux machine and issue a shutdown command on the host machine with a 10 second delay
3. Windows finishes shutting down.
4. Linux shuts down cleanly.
The install went something like this:
1. Install Linux
2. Install VMWare ESXi server for Linux
3. Install SSH
4. Create Windows XP image, install software
5. Create puTTY script to shutdown host on Windows shutdown
a. Enable option to not update image on shutdown
b. Enable option to turn on Windows VM when host machine starts
6. Enable VMware to start console automatically upon Linux startup by adding "vmware –l" command in Sessions->user startup
7. Disable CTL and ALT keys in Linux (I've not figured this out yet, but this makes it more difficult for a user to inadvertently break out of the VM session )
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