There is no real limitation on what eviroment variables you can use, there are however severe limitations on which is set.

The above code shows how to print those that are already set from perl.
However, what do you mean by "i'm looking for remote IP and remote DNS"? If you want to find it in a CGI script, the IP is one of the variables, but you have to make a reverse DNS lookup to get the name of the ip.

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