80 unspecified in the \fBbind()\fR call by either active or passive \fBTCP\fR
  81 sockets. This feature is usually used if the local address is either unknown or
  82 irrelevant. If left unspecified, the local \fBIP\fR or IPv6 address will be
  83 bound at connection time to the address of the network interface used to
  84 service the connection.
  85 .sp
  86 .LP
  87 Note that no two TCP sockets can be bound to the same port unless the bound IP
  88 addresses are different.  IPv4 \fBINADDR_ANY\fR and IPv6 unspecified addresses
  89 compare as equal to any IPv4 or IPv6 address. For example, if a socket is bound
  90 to \fBINADDR_ANY\fR or unspecified address and port X, no other socket can bind
  91 to port X, regardless of the binding address. This special consideration of
  92 \fBINADDR_ANY\fR and unspecified address can be changed using the socket option
  93 \fBSO_REUSEADDR\fR. If \fBSO_REUSEADDR\fR is set on a socket doing a bind, IPv4
  94 \fBINADDR_ANY\fR and IPv6 unspecified address do not compare as equal to any IP
  95 address. This means that as long as the two sockets are not both bound to
  96 \fBINADDR_ANY\fR/unspecified address or the same IP address, the two sockets
  97 can be bound to the same port.
  98 .sp
  99 .LP
 100  If an application does not want to allow another socket  using the
 101 \fBSO_REUSEADDR\fR option to bind to a port its socket is bound to, the
 102 application can set the socket level option \fBSO_EXCLBIND\fR on a socket. The
 103 option values of 0 and 1 mean enabling and disabling the option respectively.
 104 Once this option is enabled on a socket, no other socket can be bound to the
 105 same port.
 106 .sp
 107 .LP
 108 Once a connection has been established, data can be exchanged using the
 109 \fBread\fR(2) and \fBwrite\fR(2) system calls.
 110 .sp
 111 .LP
 112 Under most circumstances, \fBTCP\fR sends data when it is presented. When
 113 outstanding data has not yet been acknowledged, \fBTCP\fR gathers small amounts
 114 of output to be sent in a single packet once an acknowledgement has been
 115 received. For a small number of clients, such as window systems that send a
 116 stream of mouse events which receive no replies, this packetization may cause
 117 significant delays. To circumvent this problem, \fBTCP\fR provides a
 118 socket-level boolean option, \fBTCP_NODELAY.\fR \fBTCP_NODELAY\fR is defined in
 119 \fB<netinet/tcp.h>\fR, and is set with \fBsetsockopt\fR(3SOCKET) and tested
 120 with \fBgetsockopt\fR(3SOCKET). The option level for the \fBsetsockopt()\fR

  80 unspecified in the \fBbind()\fR call by either active or passive \fBTCP\fR
  81 sockets. This feature is usually used if the local address is either unknown or
  82 irrelevant. If left unspecified, the local \fBIP\fR or IPv6 address will be
  83 bound at connection time to the address of the network interface used to
  84 service the connection.
  85 .sp
  86 .LP
  87 Note that no two TCP sockets can be bound to the same port unless the bound IP
  88 addresses are different.  IPv4 \fBINADDR_ANY\fR and IPv6 unspecified addresses
  89 compare as equal to any IPv4 or IPv6 address. For example, if a socket is bound
  90 to \fBINADDR_ANY\fR or unspecified address and port X, no other socket can bind
  91 to port X, regardless of the binding address. This special consideration of
  92 \fBINADDR_ANY\fR and unspecified address can be changed using the socket option
  93 \fBSO_REUSEADDR\fR. If \fBSO_REUSEADDR\fR is set on a socket doing a bind, IPv4
  94 \fBINADDR_ANY\fR and IPv6 unspecified address do not compare as equal to any IP
  95 address. This means that as long as the two sockets are not both bound to
  96 \fBINADDR_ANY\fR/unspecified address or the same IP address, the two sockets
  97 can be bound to the same port.
  98 .sp
  99 .LP
 100 If an application does not want to allow another socket  using the
 101 \fBSO_REUSEADDR\fR option to bind to a port its socket is bound to, the
 102 application can set the socket level option \fBSO_EXCLBIND\fR on a socket. The
 103 option values of 0 and 1 mean enabling and disabling the option respectively.
 104 Once this option is enabled on a socket, no other socket can be bound to the
 105 same port.
 106 .sp
 107 .LP
 108 Once a connection has been established, data can be exchanged using the
 109 \fBread\fR(2) and \fBwrite\fR(2) system calls.
 110 .sp
 111 .LP
 112 Under most circumstances, \fBTCP\fR sends data when it is presented. When
 113 outstanding data has not yet been acknowledged, \fBTCP\fR gathers small amounts
 114 of output to be sent in a single packet once an acknowledgement has been
 115 received. For a small number of clients, such as window systems that send a
 116 stream of mouse events which receive no replies, this packetization may cause
 117 significant delays. To circumvent this problem, \fBTCP\fR provides a
 118 socket-level boolean option, \fBTCP_NODELAY.\fR \fBTCP_NODELAY\fR is defined in
 119 \fB<netinet/tcp.h>\fR, and is set with \fBsetsockopt\fR(3SOCKET) and tested
 120 with \fBgetsockopt\fR(3SOCKET). The option level for the \fBsetsockopt()\fR