Sockets #

Scope #

Role of the transport layer`
Concept of a socket and port
Comparison of transport protocols: UDP vs TCP
Structure of a UDP datagram header
Features of UDP
Creating sockets – socket() function
Binding a socket to an address – bind() function and ephemeral ports
Address structure families (sockaddr, sockaddr_in, sockaddr_in6)
Network Byte Order vs Host Byte Order
Conversion and helper functions (inet_pton, inet_ntop, getsockname, getpeername)
Connectionless communication – sendto() and recvfrom() functions
Byte stream model in the TCP protocol
TCP connection identification (4-tuple)
TCP segment structure and flag usage (SYN, FIN, RST, PSH, ACK)
Sequence numbers (SEQ) and acknowledgment mechanism (ACK)
Data management in the system kernel – transmit (Tx) and receive (Rx) buffers
Establishing a TCP connection (3-way handshake, Initial Sequence Number)
Listening sockets and connection queue (backlog, listen() function)
Accepting connections on the server – accept() function
Initiating connections by the client – connect() function
TCP connection state diagram
Reading and writing from a TCP stream – send() and recv() functions
Closing: close() vs shutdown()
TIME_WAIT state