Check for Updates in eclipse is not working

1. In Eclipse (go to Preferences > General > Network connections).
2. Select "Active Provider" as "Manual".
3. Select HTTP and click edit.
4. Enter the host and port
5. Select "Requires Authentication" and enter the username and password.
6. Repeat Step 1 to 5 for Https.
7. In "proxy bypass" section click "Add host"

In  case it does not work try to play with Active Provider - General , Manual , Native