So then do pairing once and you are done, nothing to restrict. If your device is GAP Peripheral and you want to restrict connections from other peripherals then you can easily refuse (terminate) any unwanted connection with device which is not your peer. If you want to prevent even these short connections then you can use direct advertising but remember that it's just for devices which play "nicely" and according to the spec. If some rough Central wants to issue CONNECT_REQ packet even it is not targeted by directed advertisement it indeed can try it and it's up to your device to protect itself.
So then do pairing once and you are done, nothing to restrict. If your device is GAP Peripheral and you want to restrict connections from other peripherals then you can easily refuse (terminate) any unwanted connection with device which is not your peer. If you want to prevent even these short connections then you can use direct advertising but remember that it's just for devices which play "nicely" and according to the spec. If some rough Central wants to issue CONNECT_REQ packet even it is not targeted by directed advertisement it indeed can try it and it's up to your device to protect itself.
