Created attachment 1538990 [details]
patch made by git diff
After upgrading my ntp pool server from CentOS 6.10 ntpd to CentOS 7.6 chronyd I noticed that chronyd do not respond to RFC 1059 packets. There was 8.6 % NTPv1 mode 0 requests from all IPv4 NTP pakets in one 100k-packets sample (the IPv6 clients seem to use versions 3 and 4 only).
This is already fixed in the upstream:
A patched version of chrony 3.2 is already running on my server and it responds to version 1 mode 0 packets with mode 4 (server). Hope the clients are satisfied with mode 4 although this behavior doesn't follow the RFC 1059. Unfortunately I have no such version 1 client to test if it cares about mode 4.
It would be nice to include this fix in current RHEL 7 chrony package.
The chrony package will probably be rebased in RHEL7.7 to version 3.4 (bug #1636117), which should have this bug fixed.