Proxy Detection - fsockopen. How effective?

[slyte33]

I've searched google for hours and finally found a code that has blocked over 50+ proxies that i've tried from accessing my site:

if( @fsockopen( $_SERVER['REMOTE_ADDR'], 80, $errstr, $errno, 1 ) )
{
echo "Not allowed, using proxy!";
ext();

}

 

What I am asking is, how effective is this? Can it be bypassed or anything?

 

All help on this would be appreciated, thanks!

[ferdi]

Well, that would work for HTTP proxies, that are web-based.

There are also Socks proxies, and some other's using different ports.

 

Here are some other commonly used ports by proxies:

80
88
443
554
808
1080
3124
3127
3128
3246
6588
8000
8008
8080
8085
8088
8118
9188
36673

[ferdi]

Sorry, but I don't reply with PM's.

 

You could use this to search with each port;

<?php

$ports = array(80, 88, 443, 554, 808, 1080, 3124, 3127, 3128, 3246, 6588, 8000, 8008, 8080, 8085, 8088, 8118, 9188, 36673);

foreach($ports as $port) {
    if (@fsockopen( $_SERVER['REMOTE_ADDR'], $port, $errno, $errstr, 1)) $proxy = true;
}

if (!empty($proxy)) {
    echo 'You have been detected to be using a proxy!<br />Please contact an administrator if you feel this is incorrect.';
    exit;
}

 

Just to make something more clear, even with just those commonly used ports it would take 19 seconds to check.

I'd suggest caching the valid IP's somewhere after validation.

[lAZLf]

I've had some problems with spammers using proxy servers myself.

I tried using "fsockopen()", and it worked.

 

On the other hand loading time for my website went from roughly 1.5 seconds to nearly 25 seconds!!

 

Is there anyway around this???

[ferdi]

Not while using fsockopen, it actually has to try and connect to that certain port, and... wait.

But as I said, just validate each IP once, and store it.

[Cory94bailly]

But what if the user is running a home server (publicly) or has those ports open (for any reason)? They will be banned for no reason.

[ferdi]

Well, those are really unusual ports for any browser.

Browsers ports are usually very high in range value.