Paps

I'm getting an error: 407 when trying to update the index. As you can see I'm using the v1.2.0.2, but I suspect it could be because of the network settings at work (I think they use some proxy or VPN, I can't really find out). Does anyone have an idea which port/protocol is needed to connect to the index-updating-server ? Is there another way to update the index? I guess if the connection is blocked, I wouldn't be able to use the plugin browser to download the plugins themselves, but I don't know anything about this. (and yes, I'm using paint.net at work because they outsource all their graphics request to a third party agency, so they have no better software than MS paint).