Limited support
This feature is only present in Portal 2: Community Edition and Portal: Revolution.

sv_portal_turret_shoot_through_portals_proximity

🟩 Executable on Server

sv_portal_turret_shoot_through_portals_proximity <value>

Only allow turrets to shoot through portals at players this close to portals (in square units)

Warning:

This is a cheat command and can only be used when sv_cheats is set to 1.