Force PostgreSQL clients to use SSL? I have configured ssl = on in postgresql.conf (and installed a certificate etcetera). Does this ensure that all clients will always connect over SSL?

(I.e. does ssl = on it make it impossible to connect without SSL encryption?)

Are there other ways to ensure that all clients always connect over SSL/TLS?
ssl = on only enables the possibility of using SSL.

To ensure that all clients are using SSL, add hostssl lines in pg_hba.conf, e.g.,

hostssl  all  all  0.0.0.0/0  md5


and remove all host lines.  (Well, maybe keep the ones for localhost.)

If the desire is to force the client to send a certificate, then md5 has to be changed to cert. e.g.,

hostssl  all  all  0.0.0.0/0  cert