0.0.0.0
just stand for "all IPv4 IPs", in this case it means that the middleman server listens on port 4567 on all local IPs.
It's important to note that 0.0.0.0 is not an actual IP you can use in your browser. Instead, you can navigate to any of your actually assigned local IPs, e.g. 127.0.0.1 which is the local IP on your system.
Just using localhost
doesn't work as Windows has IPv6 enabled by default (which has precedence before IPv4) and thus maps localhost
to ::1
, the local IPv6 IP. As Middleman only binds to the local IPv4 IPs, it doesn't answer on ::1
.