This is a simple lock you can install on a Ethernet jack to keep it from being unplugged. Insert the lock underneath the Ethernet tab and attach a zip tie to secure it in place like in the picture. The lock will keep the release tab from being pressed so it can't be unplugged. The little spike on the underside of the lock will keep users from sliding the lock down to remove the Ethernet plug.

This won't stop any determined thief but it will keep your average user/patron/family member from messing with things they shouldn't.

TIP: make sure you put the tab part of the zip tie on top of the lock. Otherwise you may find it difficult to get it tight enough to stay in place.