firebird in shutdown mode

Shutdown mode prevents everyone other than SYSDBA and the owner from
connecting.

This allows you to safely run metadata scripts etc and be sure no-one
else is connected while this happens.

gfix -shut f 300 aliasname

will terminate all connections after 5 minutes.

To allow logins again, you need to use

gfix -online

Here is the rest of the user’s blog discovering this firebird “mode”