Dr. Mark Humphrys

School of Computing. Dublin City University.

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Ports

See book 6.2.1 and 6.5.2

Port - Logical (not physical) connection to computer (server).
One hardware link: Many ports.
One host (physical server) can run many services (listening processes) at different addresses.

IP address = Address of a host.
IP address + port = Address of a process (service) on a host.

List of ports.
1 to 65535 (16 bit no).



List of ports

Ports set aside for some "well-known" services:

Full list:

Server machine may run multiple server processes, each contactable on different port.
Conversely, multiple clients may want to contact same port (e.g. Web server).
Client creates socket at its end. Sends request to server (at port no). Server creates socket at its end dedicated to that client.
One port: Many sockets to that port.



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