mssntp option breaking time service: tester(s) wanted

James Browning jamesb192 at
Wed Oct 4 23:11:13 UTC 2023

> On 10/04/2023 3:41 PM PDT Hal Murray <halmurray at> wrote:
> Does anybody have details on how MSSNTP signing works?
> If we can find that, we can write some POSIX code to test things.

I have test tools that should push the right buttons IF I can get
the correct magic number in the key ID. After running it with a
rainbow table, it did not work.

1) The client does client things I should not have to care about
2) The client sends an NTP request with a magic key ID
   and 16-byte NUL MAC
3) after correctness checks, the server forms a reply and then
   sends it like this.
   a) ntpsec connects to Samba (works)
   b) ntpsec sends a length (tested/seems to work)
   c) ntpsec sends serialized struct samb_key_in.
   d) samba responds with a length (always 12 IIRC)
   e) samba continues with serialized struct samba_key_out
4) ntpsec reads that and concludes that the packet is not
   correctly signed and tries to throw a couple of new error

> There is a link in ntpd/ntp_signd.c
> But I didn't find anything interesting there. (Maybe my browser was filtering
> something.)

I see walls of text that I do not want to read.

> We still need to test with real Windows at least once to make sure our test
> code does the right thing.

Yes, I probably should.


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