About this interactive
From the lesson:
- **A socket is an IP address plus a port**, written 10.1.0.3:443. The IP address picks the interface; the port picks the service.
- **The destination socket** is the server's: its port says which service the client wants (443 for HTTPS, 22 for SSH).
- **The source socket** is the client's: its OS picks an ephemeral port for each connection, so two tabs to the same site use two different source ports and the server keeps the conversations apart.
- **A reply swaps them:** the server answers from its service port to the client's ephemeral port.
- **A non-standard port** has to be typed after the address, as 10.1.0.3:42515.
The video gives the ephemeral range as 1024 to 65535; IANA sets aside 49152 to 65535 as the dynamic (ephemeral) range, and operating systems choose their own range within the 16-bit port space.
What you'll learn
- Work out the source and destination ports of a request and its reply: the destination port names the service, the client's ephemeral source port tracks the conversation
- Count sockets, each one an IP address plus a port, on a server and on a client with several connections
Aligned to
CompTIA Network+
1.4
Explain common networking ports, protocols, services, and traffic types.
Cisco CCST Networking
1.5
Describe common network applications and protocols
Key terms
- Socket
- A combination of an IP address and a port number that together identify a specific service on a specific device, forming a unique communication endpoint.
- Ephemeral Port
- A temporary source port dynamically assigned by a client operating system for the duration of a connection, used to track multiple simultaneous sessions with the same server.
- Source Port
- The port number assigned to the sending application in a network communication, used to track the originating side of a session.
- Destination Port
- The port number identifying the target service or application on the receiving device in a network communication.
- Port
- A logical endpoint for communication in a network, identified by a number that specifies a particular service or application.
- Well-Known Ports
- Port numbers ranging from 0 to 1023 that are reserved for standard, widely used services and protocols.
Topics
Ports
Sockets
Ephemeral Port
Source Port
Destination Port
Interactive
Calculation
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