database denormalization opportunity

i'm looking plan distant pause steady problem branching out tables. instance fictitious case, contend i have list users contains name, login, evidence meta data. sole scenario, contend user limited login per specific subset ip(s). thus, have 1:m relationship. everytime box such following comes up, your normal work upsurge includes have 'users' list table such 'user_ips' box you'd have something such pk(ip_id), fk(user_id) ip user_ips side.

for identical situations, folks customarily fan out heed above? there an event denormalize effectively here? maybe store ips blob buttress csv delimited fashion? strategies folks deploying today?