Ports

[BlueVenus]

Hi All,

I have just taken a course for N+ and have having trouble with the concept of ports. I learned that a port is a virtual connection allowing communination between two computers within an application. There are standard port numbers for particular applications, ie, http, telnet , email etc.

I guess I am trying to to visualize these like a serial or parallel port.. a physical connection.

Are ports open connections between two machines?

Are they always open, and how would you close them. I understand hackers can enter your computer from open ports.

How is a port number assigned and recognized within an application? I understand their are some 65,000 ports possible.

Can anyone help me visualize how these operate?

Thanks,


-Blue

 

[obenton]

It's simply part of the IP address. For example, 192.168.0.75:80 says that the packet is addressed to the program in computer 192.168.0.75 that is listening for communications on port 80.

 

[Damaged]

Actually the source and destination ports are part of the TCP header. The source and destination IP addresses are part of the IP header.