International Journal of Scientific and Research Publication (IJSRP)
It is sometimes desirable to allow access to open ports on a firewall only to authorized external users and present closed ports to all others. The authors examine ways to construct an authentication service to achieve this goal. Taking into consideration the strengths and weaknesses of existing port knocking designs they have designed their own port knocking system using a cryptographically-secure challenge response authentication system that accounts for out-of order packet delivery. They improve upon existing implementations by presenting a novel port knocking architecture with unilateral scheme, where increment in protocol execution time using unilateral authentication scheme is more for lowest inter packet delays which will reduce packet re-ordering.