Vnc connections to recent Darwin releases fail as follows:

  % vncv steve.9lab.home
  vncv: authentication failure: unknown auth type 0x51e2124

The below inline patch enables connections to recent Darwin versions,
tested on MacOS Catalina and Big Sur.  The patch is attached as well
to ease git/import.

While working on a fix I collected some information re: vnc connections
to MacOS from 9front here:

  • https://9lab.org/plan9/vnc/

Finally, here is what a connection looks like after applying the patch:

  % @{ramfs ; cd /tmp ; hget -o vnc.mp4 https://9lab.org/vid/plan9/vnc.mp4 && treason vnc.mp4}

<snip>
From: Igor Böhm <igor@9lab.org>
Date: Wed, 22 Sep 2021 06:36:54 +0000
Subject: [PATCH] vnc: enable connecting to Darwin

Tested on MacOS Catalina and Big Sur releases.
---
diff 61f37abf576a02c7f1e3561cfaba3c0457f55c9d de22c9e5d93042f458a1e6c4b7f8ef97c1f68c2a
--- a/sys/src/cmd/vnc/auth.c	Fri Aug 27 16:13:11 2021
+++ b/sys/src/cmd/vnc/auth.c	Wed Sep 22 08:36:54 2021
@@ -33,6 +33,8 @@
 		v->vers = 37;
 	else if(strncmp(msg, "RFB 003.008\n", VerLen) == 0)
 		v->vers = 38;
+	else if(strncmp(msg, "RFB 003.889\n", VerLen) == 0)
+		v->vers = 38;  /* Darwin */
 	else /* RFC6143: Any other should be treated as 3.3. */
 		v->vers = 33;
 
</snip>

Cheers,
Igor