Methods, apparati, and computer program products enforce computer network security policies by assigning network membership to a client (105) based on the client's compliance with the security policies. When a client (105) requests (305) a network address, the DHCP proxy (110) intercepts the request and assigns (350) that client (105) a logical address on the protected network (140) if the client (105) is in compliance with the security policies. If the client (105) is not in compliance with the security policies, in various embodiments, the DHCP proxy (110) assigns (350) the client (105) an address on a restricted network (145) or no network address at all.