Why run chronyd and ntpd concurrently?

Does anybody have any rationale on why a machine would be running both chronyd and ntpd concurrently on the same server?

I am thinking this is an oversight on behalf of the builder.

The only other thing I could think of would be that you would use one service as a client to another time source, and then as a mutli-homed device run the other service to be a time-source yourself.

I am hoping I can get some other feedback to see what possible rationale there might be to running both concurrently.


I believe the answer is that you cannot run both ntpd and chronyd concurrently. Using the standard time service port 123/udp, only one daemon can be active at a time. Otherwise, a port conflict would ensue.

Our organization transitioned from ntp to chrony last year, and it went very smoothly. Our main motivation was that ntp is no longer available from the base el8 repos, wherease chrony is available. We are using chrony as a client only, but it can also be configured as an authoritative time server.

Hope this helps.

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Hello John, thanks for the feedback.

Unless you need the server part systemd-timesyncd is a simple and straightforward ntp client.

@j6tqgf.s , this is a server with both packages installed, enabled and running.

I addressed my issue a long while ago.