PHP implementation of the restricted IP voting program IP source analysis, IP voting _php tutorial

PHP implementation of restricted IP voting program IP source analysis, IP polling

This paper analyzes the implementation of PHP restricted IP voting program. Share to everyone for your reference, as follows:

The need for a polling activity requires IP restrictions, each of which limits a certain chance of voting. I searched the search engine on the keywords: PHP client IP, the results are basically the following:

if (getenv (' http_client_ip ') && strcasecmp (getenv (' http_client_ip '), ' unknown ') {   $onlineip = getenv (' Http_client_ip ');} ElseIf (getenv (' http_x_forwarded_for ') && strcasecmp (getenv (' http_x_forwarded_for '), ' unknown ')) {   $ Onlineip = getenv (' http_x_forwarded_for ');} ElseIf (getenv (' remote_addr ') && strcasecmp (getenv (' remote_addr '), ' unknown ') {   $onlineip = getenv (' Remote_addr ');} ElseIf (Isset ($_server[' remote_addr ") && $_server[' remote_addr '] && strcasecmp ($_server[' Remote_ ADDR '], ' unknown ') {   $onlineip = $_server[' remote_addr ');}

This code is used in a wide range of "Discuz" forum software, as well as many open source PHP software, and the general idea is to obtain the final client IP address (the IP address of the user who can access the proxy).

Because many mature programs use this code to get the client IP address, so I also rest assured that the application in the program, fortunately, later a colleague reminded, found that this code can not be used in the restricted IP voting program, because http_x_forwarded_for this can be forged, Just add x-forwarded-for in the request. The content of this request header is received by $_server[' Http_x_forwarded_for ' on the server side.

Here I use the program to explain:

http://localhost/i.php content is obtained through the above code to obtain the IP address, and print out.

Write the generation that constructs the request, request this URL: Which adds x-forwarded-for this parameter in the request head:

$head = Array (), $head [] = ' get/i.php http/1.1 '; $head [] = ' host:localhost '; $head [] = ' x-forwarded-for:255.255.255.255 '; $head [] = ' connection:close '; $head = Join ("RN", $head) $head. = "Rnrn"; $fp = Fsockopen (' localhost '); fwrite ($FP, $hea d); $response = Array (); while ($buff = Fread ($fp, 4096)) {   $response [] = $buff;} Print join (' ', $response);

By executing this code, you know that the server side (localhost/i.php) prints 255.255.255.255.
It is indicated that this method of acquiring client IP is undesirable in restricting the voting activity of IP, and the IP address of the client can be forged. While the direct use of $_server[' REMOTE_ADDR ') is not the final IP address of the user, but the limited function is directly effective to achieve.

Of course, you can't say that the code is wrong. In some of the need for IP restrictions, should be used, for example, in some of the sites have a lot of geographical temperament site, through the user access to the IP, directly to the user's area of the subsite, and so on.

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I hope this article is helpful to you in PHP programming.

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