The initialization section gives you more information: http://pytorch.org/docs/master/distributed.html#initialization 749
Basically, if you use TCP Initialization, you can get the IP address (and some random port) of the first host machine, and use this as the address:port. For example:  init_method='tcp://10.1.1.20:23456'
This is the simplest and easiest initialization method.
If you have access to a shared file system, you can use the Shared file-system initialization 213 methods.