From f9611764c699fe98ad45996f3c87b9bdd14db716 Mon Sep 17 00:00:00 2001 From: Niklas Hambüchen Date: Sat, 11 Nov 2023 01:22:13 +0100 Subject: manual: Fix QEMU_NET_OPTS VM-side address. In my earlier commit manual: Don't suggest exposing VM port to local network. I made a side change titled Use `127.0.0.1` also on the VM side, otherwise connections to services that, in the VM, bind to `127.0.0.1` only (doing the safe approach) do not work. Unfortunately, that was wrong: QEMU inside the VM always communicates via the virtualised Ethernet interface, not via the VM's loopback interface. So trying to connect to `127.0.0.1` on the VM's side cannot work. --- .../development/running-nixos-tests-interactively.section.md | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'nixos/doc/manual/development') diff --git a/nixos/doc/manual/development/running-nixos-tests-interactively.section.md b/nixos/doc/manual/development/running-nixos-tests-interactively.section.md index a816213f37d..4b8385d7e0d 100644 --- a/nixos/doc/manual/development/running-nixos-tests-interactively.section.md +++ b/nixos/doc/manual/development/running-nixos-tests-interactively.section.md @@ -62,7 +62,7 @@ where socat is running. If your test has only a single VM, you may use e.g. ```ShellSession -$ QEMU_NET_OPTS="hostfwd=tcp:127.0.0.1:2222-127.0.0.1:22" ./result/bin/nixos-test-driver +$ QEMU_NET_OPTS="hostfwd=tcp:127.0.0.1:2222-:22" ./result/bin/nixos-test-driver ``` to port-forward a port in the VM (here `22`) to the host machine (here port `2222`). @@ -73,6 +73,11 @@ since a single port on the host cannot forward to multiple VMs. If the test defines multiple machines, you may opt to _temporarily_ set `virtualisation.forwardPorts` in the test definition for debugging. +Such port forwardings connect via the VM's virtual network interface. +Thus they cannot connect to ports that are only bound to the VM's +loopback interface (`127.0.0.1`), and the VM's NixOS firewall +must be configured to allow these connections. + ## Reuse VM state {#sec-nixos-test-reuse-vm-state} You can re-use the VM states coming from a previous run by setting the -- cgit 1.4.1