Hi all,

I have a couple of questions I've been searching on internet but I didn't find a suitable solution. The aim is that I'd like to access to my home Linux (an 8.04 Ubuntu) from outside. I already achieved with ssh, but I'd like to secure as much as I can. These are questions:

1. The account I use to login is a sudoer user. So, I want to connect with an unprivileged user, and then, only if I need, reconnect with that user inside my linux. I'd like to disable that account (root is always disabled) from remote connections. How can I do that? or Where can I find some information to disable that account from remote connections?
2. One of places I'd like to connect is from office, which has a proxy to connect to a computer out of LAN. Almost all ports are disabled. I'd like to know a way to find out which ports are open, to open in my own home the right one (a port also open in office proxy). I thought using "nmap" or "nc" to my own Linux, but it also has almost all ports closed. So connection is not possible unless I open all ports in my router, which is quite dangerous. Using nc or nmap I won't be able to know if a 'connection refused' is because my router has a certain port closed or because port in office proxy is close.
   For example I opened port 443 in my router which redirects to port 22 to my linux. I used this port, because I guessed HTTPS port was available in office proxy. I got right. However, this port is very used and I don't like to leave that port open at home.

Because of my english I don't know if my explanation is good enough, sorry Any help will be very appreciate.

Thanks