How to remember ssh password with lsyncd?

I' m using lsyncd to sync a folder between local and remote machines with default.rsyncssh config. But it asks for password every time file changes. I found there' s an option password_file, but using it causes the daemon exist giving no message. How to remember ssh password with lsyncd? Or is there any cross-platform GUI that can be easily configured to sync file/folder through ssh? I like the sync GUI of Transmit very much, but it is paid and only on OS X.