>Synopsis: Repeated NTP peers in OpenNTPD
>Category: user
>Environment:
System : OpenBSD 7.4
Details : OpenBSD 7.4 (GENERIC.MP) #0: Sun Oct 22 12:13:42 MDT 2023
r...@syspatch-74-amd64.openbsd.org:/usr/src/sys/arch/amd64/compile/GENERIC.MP
Architecture: OpenBSD.amd64
Machine : amd64
>Description:
If the same address/domain is specified multiple times in
OpenNTPD's configuration file, or if multiple domains resolve
to the same IP address, OpenNTPD will treat the same IP address
as if it was multiple peers.
>How-To-Repeat:
This can be tested by appending `server 127.0.0.1` multiple
times to the configuration file.
Alternatively, assuming a default OpenNTPD configuration file
from OpenBSD 7.4, the following entries can be added to
/etc/hosts:
127.0.0.1 time.cloudflare.com
127.0.0.1 pool.ntp.org
I noticed this bug using the default 7.4 configuration file. It
can happen because time.cloudflare.com is part of pool.ntp.org:
https://www.ntppool.org/scores/162.159.200.1
https://www.ntppool.org/scores/162.159.200.123
>Fix:
Removing the `server time.cloudflare.com` line from the
configuration file is a simple fix the user can make, but
OpenNTPD should check if an IP address it tries to add to the
list of peers is already a peer, and ignore it if so. If a
server is added with the `server` (not `servers`) keyword in the
configuration file, OpenNTPD should try the next IP the domain
resolves to if applicable.
