The UDP option not useful without call to s.send()

[mhmeadows63]

@grongor
For UDP s.send(...) needed between select.select(...) and s.close(...)

    select.select([s], [s], [s], self.timeout)
+   if self.use_udp: s.send(bytes('', 'utf8'))
    s.close()

[grongor]

Yeah, of course, that makes sense. Thank you. I didn't actually test the UDP version - I just quickly put together something that works for my case (all other knock clients failed for some reason). I will soon find some time to test the UDP functionality and then get back to you ;-)

[mhmeadows63]

No problem, yours is the only one I found with IPv6 support and it also works with link-local addresses having a %<interface> suffix.

My UDP fix suggestion is working fine for me on both IPv4 and IPv6.