[Skullmeat]

There's really no way to get caught doing something like this if you're on the same LAN as everyone else as long as your computer's name isn't anything that personally identifies you. I'd do it in the bathroom though considering the fact that cameras + network traffic timestamps can get you caught.

With regards to actually capturing data, there's plenty of shit you can find by googling "how to sniff traffic of computers on your network"

This is so wrong I dont know where to begin. First off, routers and switches extensively monitor what goes in and out of them. In addition, a properly configured switch will have port management. In fact the cisco devices have mac address limits imposed, possilby even static ones. Attempt to access that port with the wrong mac and the link goes down. The switch will shut off the port. Its even possible that the system will alert the admin of the violation, essentially giving your location away. Then theres the matter of vlans. Most networks have vlans seperating their less secure public networks from their secure, mission critical ones. Finally theres Access Control Lists. The firewall will allow or deny access from one network to another, and the options can even be specified down to a specific host. Again, unauthorized access attempts will likely trigger an alert. And security will be on your ass in a hurry, depending on how sensitive their system is. It's still possible to get around these measures, as no system is completely secure, but someone with your knowlege isn't going to be able to pull it off.