A port is a logical communication endpoint that helps an operating system deliver network data to the right application or service. This lesson introduces port numbers, transport protocols, sockets, and the way ports allow many applications to share one network address.
A network packet needs enough addressing information to reach both the correct host and the correct application on that host. An IP address identifies a network interface or host, while a port number helps identify a process or network service associated with that address and transport protocol.
All flashcards
What is a port in computer networking?
A port is a logical communication endpoint used by an operating system to direct data to a process or network service. It is not a physical connector.
What does a port number identify in combination with other addressing information?
Together with a transport protocol and IP address, a port number identifies a network endpoint associated with a process or service.
What is an internet socket?
An internet socket is an endpoint used by a process to send and receive network data. It is associated with a transport protocol, a network address, and a port number.
What does binding mean?
Binding is associating a process with a socket so the process can use a particular protocol, network address, and port for network communication.
What are ephemeral ports commonly used for?
Ephemeral ports are high-numbered ports commonly allocated for short-term use, especially at the client end of a network connection.
Quiz questions
What do ports help an operating system identify on a host?Answer: The application or service that should receive network data.
Which terms name the transport-layer data units for TCP and UDP, respectively?Answer: TCP segments and UDP datagrams
How can a firewall use port numbers when handling network traffic?Answer: Allow or block traffic according to source or destination ports.
Two applications request the same TCP IP-address and port combination. What may happen?Answer: The operating system may report a port conflict and reject one binding.
Why can several TCP clients connect simultaneously to one server listening port?Answer: Each connection is distinguished by its local and remote addresses and ports.