what's a port?

in General Discussion edited January 2014
Please forgive my stupidity, but what is a port?

As in, "a data packet was sent to port 1436..." or "you can use brickhouse to block access to mostly everything, then just enable the ports you need to use..." or "such-and-such application will listen on port whatever for incoming data, so if you've disabled access to that port, the app won't work..."

To me, a port is where you plug something in; e.g a USB port or a firewire port, or a serial port, etc.

Can anyone give me a brief explanation of what a port is, in the above context? Or tell me where I can find out? I guess it has something to do with where data from the internet goes once it gets inside your computer.


  • Reply 1 of 7
    Its a virtual door way to your computer for example the Hyper text transfer protocal (HTTP) uses port 80. So if you blocked port 80 you would not be able to browse the internet
  • Reply 2 of 7
    A network port is an "imaginary" port in a sense. Whenever your computer sends or recieves data online, each of the little data packets has a number in it called a port number that tells the computer what service it belongs to. For example, there are different ports for www pages, ftp connections, online games, and so on. The port number is used to help the computer identify what process it should give the data to for processing.

    That's a very basic description of what a port is. Maybe someone else will post into a lengthier explanation.

    [ 01-25-2003: Message edited by: Brad ]</p>
  • Reply 3 of 7
    ast3r3xast3r3x Posts: 5,012member

    (n) (1) An interface on a computer to which you can connect a device. Personal computers have various types of ports. Internally, there are several ports for connecting disk drives, display screens, and keyboards. Externally, personal computers have ports for connecting modems, printers, mice, and other peripheral devices.

    Almost all personal computers come with a serial RS-232C port or RS-422 port for connecting a modem or mouse and a parallel port for connecting a printer. On PCs, the parallel port is a Centronics interface that uses a 25-pin connector. SCSI (Small Computer System Interface) ports support higher transmission speeds than do conventional ports and enable you to attach up to seven devices to the same port.

    (2) In TCP/IP and UDP networks, an endpoint to a logical connection. The port number identifies what type of port it is. For example, port 80 is used for HTTP traffic. Also see Well-Known TCP Port Numbers in the Quick Reference section of Webopedia.

    (v) To move a program from one type of computer to another. To port an application, you need to rewrite sections that are machine dependent, and then recompile the program on the new computer. Programs that can be ported easily are said to be portable.
  • Reply 4 of 7
    thuh freakthuh freak Posts: 2,664member
    i believe this is the definition you were looking for:

    [quote]Port (n): A rich sweet fortified wine.<hr></blockquote>
  • Reply 5 of 7
    ast3r3xast3r3x Posts: 5,012member
    welcome to computer...or technology...not all ports are imaginary, like a mouse port...or USB port
  • Reply 6 of 7
    thanks all for the quick responses.

    The reason I ask has to do with internet security, since that's the context in which I first encountered "ports."

    It seems that the built in OS X internet security system pref (i.e. the built-in firewall), and programs like brickhouse basically either block certain ports, or only allow access to those ports if the incoming data is from a prespecified host.

    I don't understand how this works. Obviously, you could block port 80, but then you'd have no internet access. Or you could block port 80 but allow access only from some prespecified group of, say, your friends/family. But when people surf the web they interact with many different sites/people/organizations; not just their friends/family. I assume that there is not a specific port that "evil-doers" use. How then, do I, or my internet security program, know what port to block?

    Thanks again; I know I must sound like an idiot in this regard, but I'm trying to think this through logically and it just doesn't make sense yet.
  • Reply 7 of 7
    Pork. The other white meat. Oh. Port? See above.
Sign In or Register to comment.