From 2d464cecd1752c822d5dd58730062d381e033689 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Mon, 4 Oct 2021 11:42:51 -0700
Subject: [PATCH] cmd/tailscale: make netcheck work when logged out

Fixes #2993

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
---
 cmd/tailscale/cli/netcheck.go | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/cmd/tailscale/cli/netcheck.go b/cmd/tailscale/cli/netcheck.go
index 37c9611de..6b6e3b412 100644
--- a/cmd/tailscale/cli/netcheck.go
+++ b/cmd/tailscale/cli/netcheck.go
@@ -64,7 +64,11 @@ func runNetcheck(ctx context.Context, args []string) error {
 	}
 
 	dm, err := tailscale.CurrentDERPMap(ctx)
-	if err != nil {
+	noRegions := dm != nil && len(dm.Regions) == 0
+	if noRegions {
+		log.Printf("No DERP map from tailscaled; using default.")
+	}
+	if err != nil || noRegions {
 		dm, err = prodDERPMap(ctx, http.DefaultClient)
 		if err != nil {
 			return err