It is well established that individuals on probation have significantly fewer rights than the general population. One of the rights that is generally forfeited by a probationer is the right against search and seizure by the probation officer.
While on probation, the probation officer has a right and a duty to insure that the probationer is complying with the terms of probation. The terms of probation universally prohibit the use of illegal drugs while on probation. Likewise, a probation officer can order the probationer to cease contact with known felons or drug dealers.