Jonathan Nobels 4e6a9ffc8c feature/exitnodehealth: warn when selected exit nodes are unavailable ...

updates tailscale/corp#33007

When a selected exit node can't carry internet traffic due to a misconfiguration (wrong ID, node
deleted, routes removed, etc), blackhole default routes are installed and all internet traffic is dropped.
That is the correct behavior -- better to drop than leak to the local network -- but it was entirely silent:
the stable-ID lookup in nodeBackend.updateRouteManagerPrefs misses without a log line, and Status
leaves ExitNodeStatus nil. The user sees a healthy Tailscale with no internet. If an admin fat-fingers the
exit node name in an IT policy, for example, it's easy to break every node with zero feedback.

This adds an exit-node-unavailable health warning covering every way the selection can fail to carry
traffic (short of reachability which is a separate concern), reported via exitnodehealth.ArgExitNodeReason.

The warning names the exit node, caching its display name while it is still a peer so the name survives
its departure, and falls back to the stable ID or IP. When the selection is mandated by the ExitNodeID
or ExitNodeIP policy settings, the message tells the user to contact their network administrator instead
of suggesting they pick another exit node.

To test this, set a forced exit node policy with some random ip or node id. The warning has a 5 second
 threshold. It should clear as soon as you change to a proper exit node.

Signed-off-by: Jonathan Nobels <jonathan@tailscale.com>

2026-09-18 14:12:40 -04:00

..

ipnext.go

feature/exitnodehealth: warn when selected exit nodes are unavailable

2026-09-18 14:12:40 -04:00