If your remote side doesn't have an SSH server installed, you can use DirectTLS mode instead. The connection is encrypted, and both the client and server will authenticate each other with a certificate (so no password is needed for security). The server will automatically generate a certificate the first time it's run, and you will copy it to the client.
Run this command on the remote side to start the DirectTLS server. Replace 12345 with the port you want it to listen on.
unisync -server :12345
The first time you run it, it will say something like:
Created new key at ~/.unisync/secure.key, make sure to copy this to the client so it can connect!
listening at :12345
It's telling you that it created a TLS certificate and saved it at ~/.unisync/secure.key
. You'll need to copy this file to ~/.unisync
on the local side. Both the client and server will use it to authenticate each other, so no password is needed for security.
Make sure the client config file has these lines:
method = directtls
tls_key = secure.key
host = 123.123.123.123
port = 12345
Replace the IP and port with the correct ones for your remote side. Then run unisync normally, and it will connect and sync.