no updates possible in public network

[WytWun]

You don't mention whether you have any problem accessing websites with a browser using this wifi network.  If you can, check whether the browser is picking up proxy settings.  If you can't access websites, then proxy settings would seem to be required for both browser and software updates.

If proxy settings are required, you'll need to add statements to /etc/apt/apt.conf like these:

Code:

Acquire::http::Proxy "http://proxy.host.name:port/";
Acquire::https::Proxy "http://proxy.host.name:port/";

where the "proxy.host.name" and "port" should be replaced with the appropriate values.  You may also need to add authentication information.

You may also need to add HTTP_PROXY (and maybe http_proxy) environment variables with similar information.

You will of course then need to remove or comment out these settings when using a different network  :

Proxy handling is one thing I've found not well supported by just about all free desktop O/Ses