From 1bc3c03562f26bfa9e4e6ad5ef71132ef2cc1847 Mon Sep 17 00:00:00 2001
From: David Anderson <danderson@tailscale.com>
Date: Thu, 11 Mar 2021 21:21:15 -0800
Subject: [PATCH] control/controlclient: allow for an unset linkMon.

Signed-off-by: David Anderson <danderson@tailscale.com>
---
 control/controlclient/direct.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/control/controlclient/direct.go b/control/controlclient/direct.go
index 444e755a5..186fbe53e 100644
--- a/control/controlclient/direct.go
+++ b/control/controlclient/direct.go
@@ -547,7 +547,7 @@ func (c *Direct) sendMapRequest(ctx context.Context, maxPolls int, cb func(*netm
 		OmitPeers:  cb == nil,
 	}
 	var extraDebugFlags []string
-	if hostinfo != nil && ipForwardingBroken(hostinfo.RoutableIPs, c.linkMon.InterfaceState()) {
+	if hostinfo != nil && c.linkMon != nil && ipForwardingBroken(hostinfo.RoutableIPs, c.linkMon.InterfaceState()) {
 		extraDebugFlags = append(extraDebugFlags, "warn-ip-forwarding-off")
 	}
 	if health.RouterHealth() != nil {