Ports¶
A server listening in a machine on port 1024 or above is reachable at the same port on host 127.0.0.1. There is nothing to configure: a development server started in a machine on port 5173 answers at http://127.0.0.1:5173/ in your host browser within a second or so.
How forwarding works¶
A forwarder runs beside each VM as a user unit. Once a second it asks the VM's agent which TCP ports machines are listening on, and binds each one on host 127.0.0.1:
| The machine listens on | The host forwards to |
|---|---|
127.0.0.1, 0.0.0.0 or :: |
The VM's 127.0.0.1 |
Only ::1, such as a dev server bound to localhost |
The VM's [::1] |
Ports 1024 to 65535 are forwarded, except 5353 and 5355. Forwarding binds host loopback only; nothing is exposed on your network.
See what is forwarded¶
Each port shows its machine and its state: forwarded, or conflict with the error.
Conflicts¶
- A host program already uses the port. The forwarder reports a conflict and retries. It never displaces an existing listener.
- Two machines use the same port. Machines share the VM's network namespace, so the second one cannot listen at all, as in WSL. Give one of them another port.
Outbound traffic¶
Machines reach the network through the VM's user-mode networking and use the VM's resolver. They have no network configuration of their own.
Isolated machines have their own VM and forwarder, and their ports reach host loopback the same way.