{{fbdoc item="title" value="OPEN TCP SERVER"}}----
Opens a listening TCP server socket and binds it to a file number.

{{fbdoc item="syntax"}}##
	[[KeyPgDeclare|declare]] [[KeyPgFunction|function]] **Open Tcp Server** ( //options// [[KeyPgAs|as]] [[KeyPgString|string]], **As** [**#**]//filenumber// [[KeyPgAs|as]] [[KeyPgLong|long]] ) [[KeyPgAs|as]] [[KeyPgLong|long]]
##
{{fbdoc item="usage"}}##
	//result// = **Open Tcp Server**( //options//[,] **As** [**#**]//filenumber// )
	**Open Tcp Server** //options// **As** [**#**]//filenumber//
##
{{fbdoc item="param"}}
	##//options//##
		A comma-separated string describing the listening socket.
	##//filenumber//##
		The file number to bind to the server socket.

{{fbdoc item="ret"}}
	Returns zero (##0##) on success, or a non-zero error code on failure.

{{fbdoc item="desc"}}
	##**Open Tcp Server**## creates a listening TCP socket.  The server file number is passed to ##[[KeyPgTcpAccept|Tcp Accept]]## to accept incoming connections.  The accepted client receives its own file number and can then be read from or written to using normal file I/O statements.

	The options string accepts:
		- ##host=//name-or-address//##, optional bind address
		- ##port=//number//##, required
		- ##backlog=//count//##, optional listen backlog, default ##16##
		- ##timeout=//milliseconds//##, optional socket timeout

	Server file numbers are not used for data transfer.  Use ##[[KeyPgTcpAccept|Tcp Accept]]## and then read or write the returned client file number.

{{fbdoc item="ex"}}
	See ##examples/network/opentcp/http-server.bas## and ##examples/network/opentcp/two-connections-selftest.bas##.

{{fbdoc item="target"}}
	- TCP support is not available on all targets.  Programs that need to be portable should use target defines such as ##__FB_DOS__##, ##__FB_JS__##, and ##__FB_XBOX__## where appropriate.

{{fbdoc item="diff"}}
	- New to ""FreeBASIC"".

{{fbdoc item="see"}}
	- ##[[KeyPgOpenTcp|Open Tcp]]##
	- ##[[KeyPgTcpAccept|Tcp Accept]]##
	- ##[[KeyPgClose|Close]]##

{{fbdoc item="back" value="CatPgFile|File I/O Functions"}}