Socks 4 bind in php example

Question

<?php

error_reporting(E_ALL);

$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
if ($socket === false)
    echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";

$result = socket_connect($socket, "92.51.77.126", 1080); // socks ip

if ($result === false)
    echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "\n";

$in  = "\x04\x02";
$in .= "\x00\x50";  // http proxy port
$in .= "\xc0\xf0\x2e\x7e";  // http proxy ip address
$in .= "\x00";

socket_write($socket, $in, strlen($in));

sleep(1);

$in  = "HEAD / HTTP/1.1\r\n";
$in .= "Host: www.example.com\r\n";
$in .= "Connection: Close\r\n\r\n";

socket_write($socket, $in, strlen($in));

$out = '';
while ($out = socket_read($socket, 2048)) {
    echo $out;
}

socket_close($socket);

?>

I'd like to bind a socks 4 proxy server to connect an another proxy. This example the secound proxy is a http proxy. When connect the first is normally connected the server answer is Granted, but the communication at this time is finished. How continued the communication this example?

Answer 1

You are lucky that you get a 'Granted' reply - I do not get any reply from SOCKS server in OpenSSH, it just closes the connection...

As I understand the SOCKS4 description, the answer for type 2 (BIND) request contains a port number and an IP address; when a connection arrives to them, your program will be able to read next status packet, which tells about the connection. There is a limited time (seems 2 minutes) of waiting for the connection. This is mainly for an FTP client - an FTP server needs back connection to the client and the BIND allows the connection to be passed.

If you want to initiate a connection from your side, use type 1 (CONNECT) request. Also, make sure the port and the IP address in the request are correct - seems in your code they are 80 and 192.240.30.126.