rpcbind authorization problems

Question

I am using rpcbind (SunRPC) on Arch linux and the Python rpc.py (which use standard python socket module) interface for comunication with it. Every time I try to send a request for registration or unregistration to rpcbind, I get message that I am rejected for security reasons. The only situation where everything works is when I call rpcbind in insecure mode (rpcbind -i), but I really want to make everything works in secure mode. I found information from the rpcbind datasheet that I can make a request in secure mode only from the loopback address, but I have tried every approach I had knew to make such a socket and everything fell down. How do I connect to rpcbind in secure mode?