Extending mobile IP to ad hoc networks with the foreign agent (FA) acting as the bridge between the wired network and ad hoc networks can provide the global Internet connectivity for ad hoc hosts. The existing research in the area of the integrated wired and ad hoc network is carried out in a nonadversarial setting. This work proposes an effective solution to solve the security related problems encountered in these integrated networks. The proposed approach uses the modified minimal public based authentication protocol not only for mobility binding at the home agent (HA) but also for access control and route discovery. This security protocol also excludes malicious nodes from performing the ad hoc network routing. This paper focuses on preventing ad hoc hosts from the attacks of antiintegrity, anticonfidentiality, antiauthentication and duplication.