I just bought a new Nexus 7 a few days ago. To use my university wireless network, I need to add the proxy settings. But I can't figure out how to do that on the tablet.
How to Setup proxy settings in Nexus 7 Android 4.1
* Open "Setting" and then "Wi-Fi".
* Long press on your network, select "Modify network" and tick "Show advanced options" checkbox.
* Tap Proxy Settings, and then Manual. Enter the Proxy hostname, and the proxy port number. Then tap Save.
You can also use some Android Proxy apps from Play store to do that.