What is a Port in computer terms?
Consider a server hosted with two applications, say Yahoo Mail and Yahoo Messenger (We consider Yahoo here!)
Whenever server receives request packet from client, it reads the header appended to the packet and forwarded it to particular application i.e, based on your request, server forwards request to either Yahoo Mail or Yahoo Messenger. Remember, both applications are on same server. Hah! How the server differentiates the client request packet between Yahoo Mail request and Yahoo Messenger request? That’s where Port number plays its role. A port number is a way to identify a specific process to which the packet is to be forwarded. In this case, Yahoo Mail uses 80 and Yahoo Messenger uses 5000-5010. The server reads the user request details, look for port number and forwards to the respective application.
http://www.iana.org/assignments/port-numbers [Complete list of all port numbers]
Now you have to accept that required port needs to be opened in your computer firewall (or gateway) as well to communicate with server i.e, Yahoo Messenger. Otherwise, your computer cannot access your required application. But the security problem here is when a port is ‘open‘ and if it is poorly configured to accept request, hacker will be able to make use of those ports and can take control of your computer. That’s true!
So what measures must be taken for opening ports?
Tip 1: Whenever any application requires to open the firewall, make sure to tweak your firewall by selecting “Program exception” rather than “Port exception” for the application to work. Program exception will open the port only for that application, it will not unnecessarily allow other traffic. While Port exception will make entire port open which makes your system more vulnerable.
Tip 2: Also Open ports only for the time required. Once you are done with your need, close the port in the firewall esp, Torrents.
Tip 3: There are also free services from well trusted sources available for testing your computer for wide range of online threats. One such product is Sygate Online Services (Symantec Security Check)- Free and an effective tool that helps determine your internet security needs.
Symantec Security Check does three most common category of threats test
1. Hacker Exposure Check – Test whether most commonly used Internet applications ports are exposed to hacker’s attack.
2. Windows Vulnerability Check – Test our PC’s network identity
3. Trojan Horse Check – Test whether ports used by most common Trojan Horse applications are exposed to hacker’s attack.