Securing remote connections


 
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Operating Systems Linux Securing remote connections
# 1  
Old 09-29-2009
Securing remote connections

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 Smilie Any help will be very appreciate.

Thanks
# 2  
Old 09-29-2009
Quote:
Originally Posted by AlbertGM
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?
You can use the AllowUsers directive of sshd_config

Quote:
AllowUsers
This keyword can be followed by a list of user name patterns, separated by spaces. If specified, login is allowed only for user
names that match one of the patterns.
# 3  
Old 09-30-2009
Quote:
Originally Posted by Radar
You can use the AllowUsers directive of sshd_config
Thanks Radar,
I'll try it. I hope it makes first question answered!!

Any response in second one?
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