So you just got a brand new VPS and installed a service, say PostgreSQL onto it. You then run your web application and found it complaining that it can’t connect to 127.0.0.1 on port 5432. Since you’re a seasoned administrator, you verify it by doing netstat -an. To your surprise, you find postgresql is binding to ::1:5432, the ipv6 localhost address. You curse the VPS provider for enabling and giving you an ipv6 network interface. You don’t even need ipv6 until 2050! But all is not lost. The reason why postgresql is binding to ::1:5432 is because it binds to localhost, which points to both ::1 (ipv6) and 127.0.0.1 (ipv4). The solution is simple. Open up /etc/hosts and find a line that says
and comment it out. Restart postgresql or any other service and enjoy dotted-quad goodness again.