PHP 5, PHP 7, PHP 8
stream_socket_client - Open Internet or Unix domain socket connection
Code Examples

     [interror_code = null],
     [stringerror_message = null],
     [float|null$timeout = null],
     [int$flags = STREAM_CLIENT_CONNECT],
     [resource|null$context = null]
): resource|false

Initiates a stream or datagram connection to the destination specified by address. The type of socket created is determined by the transport specified using standard URL formatting: transport://target. For Internet Domain sockets (AF_INET) such as TCP and UDP, the target portion of the address parameter should consist of a hostname or IP address followed by a colon and a port number. For Unix domain sockets, the target portion should point to the socket file on the filesystem.


The stream will by default be opened in blocking mode. You can switch it to non-blocking mode by using stream_set_blocking.



Address to the socket to connect to.


Will be set to the system level error number if connection fails.


Will be set to the system level error message if the connection fails.


Number of seconds until the connect() system call should timeout. By default, default_socket_timeout is used.


This parameter only applies when not making asynchronous connection attempts.


To set a timeout for reading/writing data over the socket, use the stream_set_timeout, as the timeout only applies while making connecting the socket.


Bitmask field which may be set to any combination of connection flags. Currently the select of connection flags is limited to STREAM_CLIENT_CONNECT (default), STREAM_CLIENT_ASYNC_CONNECT and STREAM_CLIENT_PERSISTENT.


A valid context resource created with stream_context_create.

Return Values

On success a stream resource is returned which may be used together with the other file functions (such as fgets, fgetss, fwrite, fclose, and feof), false on failure.

Exceptions and Errors

On failure the error_code and error_message arguments will be populated with the actual system level error that occurred in the system-level connect() call. If the value returned in error_code is 0 and the function returned false, it is an indication that the error occurred before the connect() call. This is most likely due to a problem initializing the socket. Note that the error_code and error_message arguments will always be passed by reference.



UDP sockets will sometimes appear to have opened without an error, even if the remote host is unreachable. The error will only become apparent when you read or write data to/from the socket. The reason for this is because UDP is a "connectionless" protocol, which means that the operating system does not try to establish a link for the socket until it actually needs to send or receive data.


When specifying a numerical IPv6 address (e.g. fe80::1), you must enclose the IP in square brackets—for example, tcp://[fe80::1]:80.


Depending on the environment, the Unix domain or the optional connect timeout may not be available. A list of available transports can be retrieved using stream_get_transports. See for a list of built in transports.


Version Description
8.0.0 timeout and context are now nullable.

Related Functions

Example of stream_socket_client

Show all examples for stream_socket_client

PHP Version:

Function stream_socket_client:

Streams Functions

Most used PHP functions