Hmm? UDP is not connection-based, accept() cannot be called for UDP sockets. If done it will return EOPNOTSUPP. (See accept(2) for details)

I don't really understand what you are asking for?

Well, I should have put the 'accept' into quotation marks.

What I want is xinetd-like behavior which will allow to run in.tftpd under systemd. Do you need more details?

I have no experience with in.tftpd. But the default non-accept mode should suffice if tftpd just wants to listen on TFTP datagrams.

(In reply to comment #3)
> I have no experience with in.tftpd. But the default non-accept mode should
> suffice if tftpd just wants to listen on TFTP datagrams.

Hm, indeed it does work. Sorry for the noise.

One more thing -- is there a good way to specify that the daemon should be killed after, say, 3 minutes of silence?

We can't really know from the outside when a daemon is idle. The daemon could do various other cleanup jobs after having processed a datagram. Heck, we wouldn't even know when the datagram we activated the daemon for itself has been processed. There's really no way to figure that out from the outside, and hence all daemons need to implement this on their own if that's desirable.