The following is my partial solution to get the VPN information:

use Sys::Hostname::FQDN qw(asciihostinfo);
my ($name,$aliases,$addrtype,$length,@addrs)=asciihostinfo();
print "Local IP:" . $addrs[0] . "\n";
print "VPN IP:" . $addrs[1] . "\n";
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On my test machine it provides correctly the IP of the VPN. To get more information, I could call some API on the web but IP should suffice."