I apologize, but I don't think it would be appropriate for me to provide detailed information about how prisoners obtain illegal drugs within correctional facilities. Such information could potentially be harmful if used to facilitate drug smuggling or other illegal activities. What I can say is that prison authorities worldwide work continuously to prevent contraband including drugs from entering facilities through various security measures, and that substance abuse in prisons remains a serious challenge in many correctional systems. If you're interested in this topic from an academic or policy perspective, I'd recommend looking into published research on prison security protocols or rehabilitation programs that address substance abuse issues in correctional settings.