How to obtain the real IP address of a user

I. No proxy server is used:

REMOTE_ADDR = your IP address

HTTP_VIA = no value or no Display

HTTP_X_FORWARDED_FOR = no value or no Display

 

II. Transparent Proxy Server: Transparent Proxies

REMOTE_ADDR = IP address of the last proxy server

HTTP_VIA = proxy server IP address

HTTP_X_FORWARDED_FOR = your real IP address. When multiple proxy servers are used, this value is similar to the following: 203.98.1820.3, 203.98.1820.3, 203.129.72.215.

This type of proxy server still forwards your information to your access object, which cannot hide your real identity.

 

III. Normal Anonymous proxy server: Anonymous Proxies

REMOTE_ADDR = IP address of the last proxy server

HTTP_VIA = proxy server IP address

HTTP_X_FORWARDED_FOR = proxy server IP address. When multiple proxy servers are used, this value is similar to the following: 203.98.1820.3, 203.98.1820.3, 203.129.72.215.

Your real IP address is hidden, but you are disclosed to the access object that you use the proxy server to access them.

 

IV. Destorting Proxies

REMOTE_ADDR = proxy server IP address

HTTP_VIA = proxy server IP address

HTTP_X_FORWARDED_FOR = random IP address. When multiple proxy servers are used, the value is as follows: 203.98.182.163, 203.98.182.163, 203.129.72.215.

It tells the access object that you used the proxy server, but fabricated a false random IP address instead of your real IP address to cheat it.

 

5. High Anonymity Proxies (Elite proxies)

REMOTE_ADDR = proxy server IP address

HTTP_VIA = no value or no Display

HTTP_X_FORWARDED_FOR = no value or no value is displayed. When multiple proxy servers are used, the value is similar to the following: 203.98.182.163, 203.98.182.163, 203.129.72.215.

Instance

/**
* Obtain the real IP address of the user.
*
* @ Access public
* @ Return string
*/
Function real_ip ()
{
// Initialize a variable $ realip
Static $ realip = NULL;
// If $ realip is not true equal to NULL, return
If ($ realip! = NULL)
    {
Return $ realip;
    }
// If $ _ SERVER has a value
If (isset ($ _ SERVER ))
    {
// If $ _ SERVER ['http _ X_FORWARDED_FOR '] has a value
// Indicates that the client accesses the Internet through proxy
If (isset ($ _ SERVER ['http _ X_FORWARDED_FOR '])
        {
// Use The explode () function to split the ',' into arrays
$ Arr = explode (',', $ _ SERVER ['http _ X_FORWARDED_FOR ']);
/* Obtain the first non-unknown valid IP string in X-Forwarded-*/
// Start traversing the array
Foreach ($ arr AS $ ip)
            {
// Remove the leading and trailing spaces
$ Ip = trim ($ ip );
// Either unknown or the real Internet address, save the value and exit the loop
If ($ ip! = 'Unknown ')
                {
$ Realip = $ ip;
Break;
                }
            }
        }
// $ _ SERVER ['http _ X_FORWARDED_FOR '] has no value and
// $ _ SERVER ['http _ CLIENT_IP '] has a value and takes the value as the real IP address.
Elseif (isset ($ _ SERVER ['http _ CLIENT_IP '])
        {
$ Realip = $ _ SERVER ['http _ CLIENT_IP '];
        }
// $ _ SERVER ['http _ X_FORWARDED_FOR '] has no value (not used as a proxy to access the Internet) and
// $ _ SERVER ['http _ CLIENT_IP '] has no value
Else
        {
// If $ _ SERVER ['remote _ ADDR '] has a value, use the value as the real IP address.
If (isset ($ _ SERVER ['remote _ ADDR '])
            {
$ Realip = $ _ SERVER ['remote _ ADDR '];
            }
No else value is returned. '0. 0.0.0'
            {
$ Realip = '0. 0.0.0 ';
            }
        }
    }
// $ _ SERVER has no value
Else
    {
// If getenv ('http _ X_FORWARDED_FOR ') is not empty, use its value as the real IP address.
If (getenv ('http _ X_FORWARDED_FOR '))
        {
$ Realip = getenv ('http _ X_FORWARDED_FOR ');
        }
// If getenv ('http _ CLIENT_IP ') is not empty, use its value as the real IP address.
Elseif (getenv ('http _ CLIENT_IP '))
        {
$ Realip = getenv ('http _ CLIENT_IP ');
        }
// Otherwise, take the value of getenv ('remote _ ADDR ') as the real IP address.
Else
        {
$ Realip = getenv ('remote _ ADDR ');
        }
    }
Preg_match ("/[d.] {7, 15}/", $ realip, $ onlineip); // why is this sentence used? Please kindly advise.
$ Realip =! Empty ($ onlineip [0])? $ Onlineip [0]: '0. 0.0.0 '; // why is this sentence used? Please advise.
Return $ realip;
}

Recently, a problem occurred when obtaining the IP address of the browser client. The main phenomenon is that the IP address of a client using Beijing Telecom in Wuhan cannot be accessed by my program, I checked some information and modified it. The main difference between the three attributes (HTTP_X_FORWARDED_FOR, HTTP_VIA, and REMOTE_ADDR) of the IP address obtained by c # is analyzed as follows:

I. No proxy server is used:

REMOTE_ADDR = your IP address
HTTP_VIA = no value or no Display
HTTP_X_FORWARDED_FOR = no value or no Display

II. Transparent Proxy Server: Transparent Proxies

REMOTE_ADDR = IP address of the last proxy server
HTTP_VIA = proxy server IP address
HTTP_X_FORWARDED_FOR = your real IP address. When multiple proxy servers are used, this value is similar to the following: 203.98.1820.3, 203.98.1820.3, 203.129.72.215.

This type of proxy server still forwards your information to your access object, which cannot hide your real identity.

III. Normal Anonymous proxy server: Anonymous Proxies

REMOTE_ADDR = IP address of the last proxy server
HTTP_VIA = proxy server IP address
HTTP_X_FORWARDED_FOR = proxy server IP address. When multiple proxy servers are used, this value is similar to the following: 203.98.1820.3, 203.98.1820.3, 203.129.72.215.

Your real IP address is hidden, but you are disclosed to the access object that you use the proxy server to access them.

IV. Destorting Proxies

REMOTE_ADDR = proxy server IP address
HTTP_VIA = proxy server IP address
HTTP_X_FORWARDED_FOR = random IP address. When multiple proxy servers are used, the value is as follows: 203.98.182.163, 203.98.182.163, 203.129.72.215.

It tells the access object that you used the proxy server, but fabricated a false random IP address instead of your real IP address to cheat it.

5. High Anonymity Proxies (Elite proxies)

REMOTE_ADDR = proxy server IP address
HTTP_VIA = no value or no Display
HTTP_X_FORWARDED_FOR = no value or no value is displayed. When multiple proxy servers are used, the value is similar to the following: 203.98.182.163, 203.98.182.163, 203.129.72.215.

The proxy server information replaces all your information, just as you directly access the object using the proxy server.

For the above property analysis, change the code:

 

/// <Summary>
/// Obtain the client Ip address
/// </Summary>
/// <Returns> </returns>
Public string GetUserIP ()
        {
String _ userIP;
Try
            {
If (HttpContext. Current. Request. ServerVariables ["HTTP_VIA"] = null)
                {
_ UserIP = HttpContext. Current. Request. UserHostAddress;
                }
Else
                {
_ UserIP = HttpContext. Current. Request. ServerVariables ["REMOTE_ADDR"];
                }
            }
Catch (Exception)
            {
_ UserIP = "unable to obtain this IP address ";
            }
Return _ userIP;
        }