Network Security guide for the home or small business network – Part 6 – Secure your services
This one is going to be tougher. Of what we’ve looked at so far this will probably take more work and learning than any of the others. The good news is, depending on your situation you may need to do less here. IF you have decided that your pc (or network) has ports open to the outside world, so that incoming connections can be listened for. You NEED to do this. For every service that is accessible from the outside world…
it needs to get an even higher priority for the security updates that we talked about last time. Beyond that, if it’s accessible from the outside world you need to do some soul-searching. Why is it accessible from the outside? Who is to have access to it? and How can we make it as secure as possible?
If it’s a web server… maybe you’re trying to do a small demo web site off a machine. That’s fine and good, but is the web server accepting connections from locations other than those that need to? Maybe the demo should be password protected. Maybe certain network addresses need to be denied access outright? Maybe, we need to evaluate exactly what data is shown? Are the folders in the webserver browsable? Should they be?
Another example is a ssh server (secure shell) for remote access on linux systems. Does your configuration allow remote root login with the appropriate password? Does it use both SSH 1 and 2 protocols or just 2? Does it restrict logins to any specific network or networks? Specific users? How can it be tightened down?
Of course, the real starting point has to be – do I need to run this service to the outside world? The default mindset should be no and you should have to justify WHY it should be available. Then, ok I can make it available in the narrowest way possible. Broader access if that can be justified. The other thing to consider is – are there better (more secure) ways to acheive the goal of an open service to the outside world? The bottom line is how can we open up the least access to the outside world to achieve what we need to do.
This is the part where you have to learn a bit about what services listen for connections from the outside world and how to 1) do it differently or 2) make them more secure.