How to get User's IP adress using Perl

In a server environment there several servers are involved in an architecture with load balancer for example the user's IP-address are retrieved using  HTTP_X_FORWARDED_FOR environment parameter in PERL:

my @ip_address = split(/,/, $ENV{'HTTP_X_FORWARDED_FOR'});
print   $ip_address[0] ;

In all other language you should be able to access to  HTTP_X_FORWARDED_FOR:

Ruby:

@remote_ip = request.env["HTTP_X_FORWARDED_FOR"]