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LISTEN(2)		  FreeBSD System Calls Manual		     LISTEN(2)

NAME
     listen -- listen for connections on a socket

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/socket.h>

     int
     listen(int	s, int backlog);

DESCRIPTION
     To	accept connections, a socket is	first created with socket(2), a	will-
     ingness to	accept incoming	connections and	a queue	limit for incoming
     connections are specified with listen(), and then the connections are
     accepted with accept(2).  The listen() call applies only to sockets of
     type SOCK_STREAM or SOCK_SEQPACKET.

     The backlog parameter defines the maximum length the queue	of pending
     connections may grow to.  If a connection request arrives with the	queue
     full the client may receive an error with an indication of	ECONNREFUSED,
     or, if the	underlying protocol supports retransmission, the request may
     be	ignored	so that	retries	may succeed.

     The sysctl(3) MIB variable	``kern.ipc.somaxconn'' specifies a hard	limit
     on	backlog; if a value greater than kern.ipc.somaxconn or less than zero
     is	specified, backlog is silently forced to kern.ipc.somaxconn.

RETURN VALUES
     The listen() function returns the value 0 if successful; otherwise	the
     value -1 is returned and the global variable errno	is set to indicate the
     error.

ERRORS
     Listen() will fail	if:

     [EBADF]		The argument s is not a	valid descriptor.

     [ENOTSOCK]		The argument s is not a	socket.

     [EOPNOTSUPP]	The socket is not of a type that supports the opera-
			tion listen().

SEE ALSO
     accept(2),	connect(2), socket(2), sysctl(3), sysctl(8)

HISTORY
     The listen() function call	appeared in 4.2BSD.  The ability to configure
     the maximum backlog at run-time, and to use a negative backlog to request
     the maximum allowable value, was introduced in FreeBSD 2.2.

FreeBSD	10.1		       November	3, 1995			  FreeBSD 10.1

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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