sur Tower

ssh-keygen -t rsa -b 2048 -f /root/.ssh/Tower-rsync-key

de Tower

scp /root/.ssh/Tower-rsync-key.pub root@192.168.1.203:/root/

sur patate2

cd /root/
if [ ! -d .ssh ]; then mkdir .ssh ; chmod 700 .ssh ; fi 
mv Tower-rsync-key.pub .ssh/ 
cd .ssh/ 
if [ ! -f authorized_keys ]; then touch authorized_keys ; chmod 600 authorized_keys ; fi 
cat Tower-rsync-key.pub >> authorized_keys 

https://forums.unraid.net/topic/52830-syncronize-servers-using-rsync-over-ssh-next-door-or-across-the-world/