synching postgresql database between two EC2 instances

When running (fictitious ip addresses) on an EC2 instance that is intended to be a slave postgresql database:

ubuntu@ip-127-31-71-50:/var/lib/postgresql/9.3$ sudo -u postgres pg_basebackup -h 54.419.311.274 -D /var/lib/postgresql/9.3/main -U rep -v -P -x

The response is:

pg_basebackup: could not connect to server: could not connect to server: Connection refused
    Is the server running on host "54.419.311.274" and accepting
    TCP/IP connections on port 5432?

Having run this command on non_AWS instances successfully, I wonder what configuration is required under AWS to make this run properly. User postgres exists on the master as

sudo su postgres

allows editing postgre via its main user.

postgresql.conf on master EC2 instance has

listen_addresses = 'localhost,54.419.311.274,54.86.79.188'

What am I missing?