Dave Silvia wrote :1683
`HTTP_REFERER`
The address of the page (if any) which referred the user agent to the current page. This is set by the user agent. Not all user agents will set this, and some provide the ability to modify HTTP_REFERER as a feature. In short, it cannot really be trusted.
Dave Silvia wrote :1684
Perhaps a better choice might be:
`REMOTE_ADDR`
The IP address from which the user is viewing the current page.
`REMOTE_HOST`
The Host name from which the user is viewing the current page. The reverse dns lookup is based off the REMOTE_ADDR of the user.
Note:
Your web server must be configured to create this variable. For example in Apache you`ll need HostnameLookups On inside httpd.conf for it to exist. See also gethostbyaddr().
`REMOTE_PORT`
The port being used on the user`s machine to communicate with the web server.