Following software must be installed on both servers:
At network level, connections between the PostgreSQL port (default: 5432) must be possible between all nodes.
Passwordless SSH connectivity between all servers in the replication cluster is not required, but is necessary in the following cases:
if you need repmgr to copy configuration files from outside the PostgreSQL data directory (as is the case with e.g. Debian packages); in this case rsync must also be installed on all servers.
to perform switchover operations
Tip: Consider setting ConnectTimeout to a low value in your SSH configuration. This will make it faster to detect any SSH connection errors.