Getting user IP

I want to receive the user's ip address when he's browser loads the page.
1. Is it possible to do so in cgi or should it run a c program ? or there is a simpler way ?
2. if to use cgi, how to call it from the html when the page is loaded to the browser ?
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CGI can run a c program.
further to Ozo's comment...

CGI is not a language as such - it's an interface between a web browser at the client, and a program on the server.  This program may be written in (almost) any language.  Perl is used mostly, but C or C++ is often used where speed is important.

as ozo briefly mentions, there is an environment variable called REMOTE_ADDR that holds the remote user's IP address. this environment variable is set by the web server when your CGI program is called.  in Perl, use:


to retrieve it, and in C it can be retrieved using the getenv() function.

There is also a lot of other information about the user that can be retrieved through the use of environment variables - such as:

HTTP_USER_AGENT - user's browser
HTTP_REFERER - the document that the user came from before they got to the CGI

There are others too - i can't think of a URL offhand - but a web search should be productive


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