If you are using Eclipse behind a proxy you will sometimes notice, that your network connection will fail although you have filled out your proxy settings correctly.
Especially when using the update center to install new software.
Eclipse will try to establish the network connection but without any success.
But there is a simple solution for the problem.
Just edit your eclipse.ini file (could be foound in the eclipse installation root directory) and append the following line:
-Dorg.eclipse.ecf.provider.filetransfer.excludeContributors=org.eclipse.ecf.provider.filetransfer.httpclient
Restart eclipse and you will be happy ;-)
