Symfony: sfGuardUser restrict access only to certain modules

set global security.yml
is_secure: off
and then in your modules/<Nume modul>/config create a new security.yml file where you add

all:
is_secure: on
credentials: [admin, selling_team , or what ever you want to set in ]

to enable action level restriction it would be:
all:
is_secure: on
credentials: [admin, selling_team , or what ever you want to set in ]
your_action:
is_secure: on
credentials: [ whatever you want ]