Is it possible to have a single host name with multiple IP addresses? The hostname will be used to access a box in LAN with 192.168.x.y and from outside with IP w.x.y.z which is portforwarded to that box in a router.
Yes, it is. You can use hostfile switching program like http://hostprofiles.codeplex.com/ (for windows and linux) and http://osxdaily.com/2010/04/29/switch-and-manage-multiple-hosts-files-with-gas-mask/ (for mac) to do that. You will have
home host file
outside host file
You will switch the hostfile accordingly and use the hostname, "myutilbox.twh" to access your box.
Why not use a simple batch file or script to rotate between HOSTS files?
For example, this works on Windows when run as Administrator (you may have to un-hide your HOSTS file and make it writable first):
Run it and it will swap HOSTS for HOSTS.OTHER and the next time you run it, it will switch them back.