UDP in Gates

From Cornell CS Wiki
Jump to: navigation, search

Is your DNS, VPN, or other UDP-based protocol not working in Gates Hall? This is likely because Gates Hall currently (as of Feb 2014) uses an ACL to filter packets. The default settings are to drop all incoming UDP packets, which can cause problems for common setups!

Quick test to see if you're blocked

Unsure if you're affected? Here's how to check.


This command tries a DNS lookup to an off-campus server (run by Google) at for the domain name "google.com""

   dig @ google.com && echo "UDP worked" || echo "UDP blocked"

If you can receive incoming UDP packets, this command will quickly succeed and print UDP worked. If packets are blocked, it will take a while to time out and then print UDP blocked.


<Someone with Windows fill this in>


Use RedRover

If you're using a laptop with wireless, you can use RedRover, which allows incoming UDP packets. Note that this may break printing though.

Request a UDP unblock

Until a more permanent solution is found, you'll have to request your computer to be individually unblocked for incoming packets. You can do so via the following few steps:

  1. Go here: https://help.coecis.cornell.edu/index.php?/Default
  2. Click Submit IT Ticket
  3. Submit a ticket, perhaps using this template:
    1. Type: Network Issues
    2. Subject: Unblock UDP to Gates Computer
    3. Body: UDP is currently blocked by default in Gates hall. Please add the appropriate rule to unblock UDP either via MAC address (mine is ________) or IP (current IP on the Gates network is ________). Thanks.