(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

socket_bindBinds a name to a socket


socket_bind(Socket $socket, string $address, int $port = 0): bool

Binds the name given in address to the socket described by socket. This has to be done before a connection is established using socket_connect() or socket_listen().



A Socket instance created with socket_create().


If the socket is of the AF_INET family, the address is an IP in dotted-quad notation (e.g.

If the socket is of the AF_UNIX family, the address is the path of a Unix-domain socket (e.g. /tmp/my.sock).

port (Optional)

The port parameter is only used when binding an AF_INET socket, and designates the port on which to listen for connections.

Valor Retornado

Retorna true em caso de sucesso ou false em caso de falha.

The error code can be retrieved with socket_last_error(). This code may be passed to socket_strerror() to get a textual explanation of the error.

Registro de Alterações

Versão Descrição
8.0.0 O parâmetro socket agora espera uma instância de Socket; anteriormente, um resource era esperado.


Exemplo #1 Using socket_bind() to set the source address

// Create a new socket
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);

// An example list of IP addresses owned by the computer
$sourceips['kevin'] = '';
$sourceips['madcoder'] = '';

// Bind the source address
socket_bind($sock, $sourceips['madcoder']);

// Connect to destination address
socket_connect($sock, '', 80);

// Write
$request = 'GET / HTTP/1.1' . "\r\n" .
'Host:' . "\r\n\r\n";
socket_write($sock, $request);

// Close




This function must be used on the socket before socket_connect().


Windows 9x/ME compatibility note: socket_last_error() may return an invalid error code if trying to bind the socket to a wrong address that does not belong to your machine.

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User Contributed Notes 7 notes

21 years ago
If you want to reuse address and port, and get rid of error: unable to bind, address already in use, you have to use socket_setopt (check actual spelling for this function in you PHP verison) before calling bind:

if (!socket_set_option($sock, SOL_SOCKET, SO_REUSEADDR, 1)) {

This solution was found by
Christophe Dirac. Thank you Christophe!
dresende at thinkdigital dot pt
12 years ago
Regarding previous post:

"0" has address is no different from "" -> accept only from local host
w.x.y.z (valid local IP) -> accep only from this network -> accept from anywhere
php50613160534 dot 3 dot korkman at spamgourmet dot org
18 years ago
Use 0 for port to bind a random (free) port for incoming connections:

socket_bind ($socket, $bind_address, 0);
socket_getsockname($socket, $socket_address, $socket_port);

$socket_port contains the assigned port, you might want to send it to a remote client connecting. Tested with php 5.03.
ealexs at gmail dot com
2 years ago
I am posting this as I've spent a few hours debugging this.

If you use socket_create / socket_bind with Unix domain sockets, then using socket_close at the end is not sufficient. You will get "address already in use" the second time you run your script. Call unlink on the file that is used for Unix domain sockets, preferably before you start to create the socket.


= "./test.sock";

if (
# optional file lock
$socket = socket_create(AF_UNIX, SOCK_STREAM, 0);
# ... socket_set_option ...
socket_bind($socket, $socket_file);
# ...
# optional : release lock

gasket at cekkent dot net
21 years ago
The aforementioned tidbit about using NULL to bind to all addresses did not work for me, as I would receive an error about unknown address. Using a 0 worked for me:

socket_bind ($socket, 0, $port)

This also allows you to receive UDP broadcasts, which is what I had been trying to figure out.
gabriel at plenitech dot fr
10 years ago
When doing Unix sockets, it might be necessary to chmod the socket file so as to give Write permission to Group and/or Others. Otherwise, only the owner is allowed to write data into the stream.


= '/tmp/my.sock';
socket_bind($socket, $sockpath);
//here: write-only (socket_send) to others, only owner can fetch data.
chmod($sockpath, 0702);
12 years ago
It appears for the $address parameter:

accepts clients from localhost (eg.

accepts clients from localhost, and the server's network (eg.,,

'0' or 0
accepts clients from localhost, the server's network, and external networks (eg.,,,
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