UNIX Network Programming is a popular book commonly referred to as UNP. It is a two volume series (at this time), written by W. Richard Stevens.

Volume 1: Network APIs - Sockets and XTI
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Ch. 1: Introduction
Ch. 2: The Transport Layer: TCP and UDP
Ch. 3: Sockets Introduction
Ch. 4: Unnamed
Ch. 5: TCP Client-Server Example
Ch. 6: I/O Multiplexing: the select and poll Function
Ch. 7: Socket Options
Ch. 8: Elementary UDP Sockets
Ch. 9: Elementary Name and Address Conversions
Ch. 10: IPv4 and IPv6 Interoperability
Ch. 11: Advanced Name and Address Conversions
Ch. 12: Daemon Processes and inetd Superserver
Ch. 13: Advanced I/O Functions
Ch. 14: Unix Domain Protocols
Ch. 15: Nonblocking I/O
Ch. 16: ioctl Operations
Ch. 17: Routing Sockets
Ch. 18: Broadcasting
Ch. 19: Multicasting
Ch. 20: Advanced UDP Sockets
Ch. 21: Out-of-Band Data
Ch. 22: Signal-Driven I/O
Ch. 23: Threads
Ch. 24: IP Options
Ch. 25: Raw Sockets
Ch. 26: Datalink Access
Ch. 27: Client-Server Design Alternatives

Volume 2: Interprocess Communications
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Ch. 1: Introduction
Ch. 2: Posix IPC
Ch. 3: System V IPC
Ch. 4: Pipes and FIFOs
Ch. 5: Posix Message Queues
Ch. 6: System V Message Queues
Ch. 7: Mutexes and Condition Variables
Ch. 8: Read-Write Locks
Ch. 9: Record Locking
Ch. 10: Posix Semaphores
Ch. 11: System V Semaphores
Ch. 12: Shared Memory Introduction
Ch. 13: Posix Shared Memory
Ch. 14: System V Shared Memory
Ch. 15: Doors
Ch. 16: Sun RPC
Appendix A: Performance Measurements
Appendix B: A Threads Primer
Appendix C: Miscellaneous Source Code
Appendix D: Solutions to Selected Exercises