Eclipse forgets my proxy credentials

This usually happens when you are using a different eclipse installation to access your old eclipse workspace. Its something to do with the new installation not being able to access the secure storage created by your old installation. Here's what I did to solve it:

Close eclipse completely. Now fire up terminal or command prompt or whatever and navigate to your home directory. In my case it is '/Users/manthan/' directory.

Now cd into .eclipse/org.eclipse.equinox.security directory.

cd .eclipse/org.eclipse.equinox.security

If you list files, you should see a file called secure_storage in it. Rename that to secure_storage.old or something like that. You can delete it if you want but I prefer to rename things, make sure it works and then delete the renamed file.

mv secure_storage secure_storage.old

Now making sure that the secure_storage file has been renamed successfully, open eclipse and now try saving your credentials. It should ask for your key store master password and other stuff. 

That's it! You're done.