Re: Firewall settings
Then you've already got a firewall in the router, and you don't need to be using a personal firewall too. Simply turn GUFW off (or "Allow all") and you'll remain just as safe.
Originally Posted by 3dmatrix
Also, just because a port isn't explicitly blocked, doesn't mean that it's "open"; let me use an analogy.
Using a router's firewall AND a personal firewall is like unplugging your phone, AND THEN taking the phone off the hook. Obviously, taking the unplugged phone off the hook is not going to help, you're already not going to receive any phone calls because the phone is unplugged!
If the phone was plugged in and on the hook, you can receive phone calls. There's nothing blocking that. But if the phone rings and nobody's at home, or nobody's listening, then nobody will pick up the phone and so the call won't actually be connected. Same thing with the firewall - if a port is not blocked, but there's no program currently listening on that port, there will not be a connection to your computer. The end result, really, is the same as if you had the port blocked, or if you had your telephone unplugged.
Just because somebody can dial the number and make your phone ring, doesn't mean that they can speak to you. They can only speak to you if you're home, and currently listening for an incoming call, and actually pick up the receiver. If any of these things is not true, they can't speak to you. If the program isn't running, or the program isn't listening for an incoming call, or the program decides not to pick up, then no attacker can connect to your computer on that port.
If in doubt, you should read up a bit more about what a firewall actually does and how network connections ("sockets") work. I'm sure Google can hook you up with an article.
I try to treat the cause, not the symptom. I avoid the terminal in instructions, unless it's easier or necessary. My instructions will work within the Ubuntu system, instead of breaking or subverting it. Those are the three guarantees to the helpee.