Detecting firewall

zingbats

I am trying to set up a system where a script can "attack" various ports on a computer and display whether the port is open, closed or "stealthed". This will help the user know whether their computer is safe or not. Do you know HOW to send packets to the remote computer.

NOTE: THIS IS NOT A HACKING POST!

LordShryku

Have you tried pinging it?

zingbats

I don't think you understand... I need a system to probe specific ports and see whether the response is stealth, open or closed... like:

https://grc.com/x/ne.dll?bh0bkyd2

Alex.

laserlight

I think you might have to use fsockopen() for that sort of thing.

zingbats

<?php
$fp = fsockopen ("www.example.com", 80, $errno, $errstr, 30);
if (!$fp) {
    echo "$errstr ($errno)<br>\n";
} else {
    fputs ($fp, "GET / HTTP/1.0\r\nHost: www.example.com\r\n\r\n");
    while (!feof($fp)) {
        echo fgets ($fp,128);
    }
    fclose ($fp);
}
?>

(Taken from http://uk2.php.net/fsockopen)

I have determined that this opens a socket on port 80 on the domain name www.example.com. What would $errno and $errstr be? And, also, what does the 30 mean?

LordShryku

Take from the same page....

If the call fails, it will return FALSE and if the optional errno and errstr arguments are present they will be set to indicate the actual system level error that occurred in the system-level connect() call. If the value returned in errno 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 errno and errstr arguments will always be passed by reference.

And the 30 is the timeout

Note: If you need to set a timeout for reading/writing data over the socket, use socket_set_timeout(), as the timeout parameter to fsockopen() only applies while connecting the socket.

laserlight

int fsockopen ( string target, int port [, int errno [, string errstr [, float timeout]]] )

I'm not too familiar with fsockopen() myself, but my interpretation is that errno and errstr would help determine the nature of any error, presumably depending on the protocol.