If you are receiving the rip44 announcements, you have properly configured your tunnel to receive IP-in-IP encapsulation from 44.0.0.1. Feel free to use:44.0.0.1 responds to pings received from the Internet. It does not respond to pings coming into it over an encap connection to it, for some reason that I've not been able to figure out. I believe it to be a difficulty in getting it to recognize decapped pings.