Just a quick one tonight.
You can never be too careful with security and your connection to the Internet. One way the bad guys can try and get into your computers or your router is when you have open ports exposed to the outside world. For those that don’t know, a computer has two sets of 65,536 ports (one set for sending data and another set for receiving data). Ports numbers 0 to 1023 have had some long established uses, for example:
- port 25 for SMTP (sending e-mail),
- port 80 for traditional web traffic,
- port 110 for POP3 (downloading e-mail),
- port 443 for secure webpage traffic.
In most cases, you shouldn’t have too many ports open. If you use stuff like BitTorrent which requires port forwarding to work you may have used port forwarding to allow traffic from the Internet to get to your computer unhindered.
In terms of security, you should not open more ports than necessary – it’s the fundamental principle of least privilege.
So how do you work out what ports are open?
Check out Shields UP! There is a raft of options including scans for:
- file sharing ports,
- common ports,
- service ports.
What Shields UP! will do is check the prescribed ports on your public Internet connection and check what sort of response is received. Ideally, you want all of your ports to report as being “stealth” (which means your computer does not respond at all to requests on those ports). This gives the impression to the outside world that no computer actually exists on your IP address. Otherwise, if a port shows up as “closed” or “open” you may need to investigate what is running on your computer or how your router is configured to lock it down.
So have a go of Shields UP! Knowing what ports are open is the first step to securing your computer. As always, the best solution is to have a hardware router and a firewall but making sure they are properly configured us essential when it comes to security.
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