Good backups are the best defense against system damage. Perform backups before placing a system on the trade show network then continue backups throughout the show and again following the event. Most are exhibitors who have a legitimate need to run them during the course of product demonstrations. Particularly prone to eavesdropping are telnet sessions. As mentioned previously, authentication tokens and ssh are a simple way to add security to system account access.
Many routers support basic packet filtering.
If a router can be deployed between the local network and the show's network, general basic packet filtering should be employed. Specific global service denials. Specific service acceptance. Match source addresses to routing information available for the interface. 2 Filter all source routed packets unless source routing is specifically needed.