Sequenced Packet Socket connections are connection oriented sockets. The normal socket connection APIs such as bind/listen/accept/connect are used to establish a socket connection. In all respects, as far as the connection establishment is concerned, it is equivalent to a TCP stream socket connection.

The SOCK_SEQPACKET socket connection has the below properties:

• The TCP stream socket does not maintain socket boundaries. However, the SOCK_SEQPACKET connection preserves message boundaries similar to a UDP socket connection.
• The communication via SOCK_SEQPACKET is reliable similar to a TCP stream connection
• The messages are transmitted to the receiver in order and sequence of packets is maintained

Linux supports SOCK_SEQPACKET for Unix domain sockets. Certain protocols like SCTP supports Sequenced socket connection. UDP and TCP protocols do not support SOCK_SEQPACKET connection

 Reference:

• The Linux Programming Interface – Michael Kerrisk
• Unix Network Programming – W. Richard Stevens, Bill Fenner, Andrew M. Rudoff

Sequenced Packet Socket code example