Comment # 2 on bug 1193592 from David Anes

Hi Thomas,

I found what's happening and it's actually easier than I thought (and expected,
by the way).

Look, we've gone lately through a hardening effort of system services/daemons
and rsyncd is one of the services that have been hardened. This is what we did
for rsyncd:
*
https://build.opensuse.org/package/rdiff/openSUSE:Factory/rsync?linkrev=base&rev=74

You have two options here:
1) Use only SSH protocol, as you already mentioned, although it may be
inconvenient for you.
2) Modify your rsyncd.service file and use ProtectKernelModules=false instead
of the defaults, as you are syncing /usr/lib/modules. Don't forget to restart
the daemon afterwards.

Be aware that the second options makes your system slightly less secure.
Please, try a let us know if this works for you.