TCP ports 1024 – 49151 are available for use by services or applications, and you can register them with IANA, so they are considered semi-reserved. The first 1023 TCP ports are the well-known ports reserved for applications like FTP(21), HTTP(80), or SSH(22) and the Internet Assigned Numbers Authority (IANA) reserves these points to keep them standardized. Each service running on the computer needs to “listen” on a designated port. If you send a packet to the IP address, the computer knows what port to route the packet to based on the application or packet contents. There are two kinds of network ports on each computer (65,536 of each for a total of 131,082 network ports):Įach computer has an Internet Protocol (IP) address, which is how the network knows which computer to send packets to. For a more in-depth explanation, we need to establish a little background information. What is a Port?Ī port is a virtual location where networking communication starts and ends (in a nutshell).

The status helps network engineers diagnose network issues or application connectivity issues, or helps attackers find possible ports to use for infiltration into your network. If you wanted to check to see if your web server was operating correctly, you would check the status of port 80 on that server to make sure it was open and listening.

So what a port scanner does is send a packet of network data to a port to check the current status. Get the Free Pen Testing Active Directory Environments EBookĪ port scanner sends a network request to connect to a specific TCP or UDP port on a computer and records the response.

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