At this point we would like to point out once again that installations that have been downloaded via a download image must be protected against unauthorized access! The minimum is the immediate change of the passwords for pi, root, etc…. But this is only one topic, here are some hints as a suggestion:
change ssh port (no longer 22/tcp)
only unlock the ports that are absolutely necessary
Limit the number of accesses and possible intervals with iptables
allow ssh access only from certain computers
ideally set up ssh access via certificates
There are lots of instructions on the Internet on how to protect your servers against unauthorized access, but explaining this can no longer be the job of a SvxLink website.