Distinguishing between connections in pg_hba.conf

Hi,

I have a web application (PHP) which runs on its own box, and connects to a
database on a second box. The database box is behind the firewall and only
accepts connections from the web server.

I have set up stunnel on the web server and I would like to allow some
limited external direct access to the db server, but I would like
connections from stunnel to only access a specific database. The problem is
that both the web server and the stunnel connections will come from the same
box, and hence the same IP address, is there anyway I can distinguish
between these two connection methods in pg_hba.conf? (I can't do it on
username either)

Thanks for any advice

Adam

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