Port knocking is a technique for adding an additional layer of access control before accessing certain ports on a computer. Unfortunately in the standard port knocking protocol, the knock sequence can be eavesdropped by anyone, and retransmitted/replayed. The replay of knock sequence by an adversary will omit the access control provided by port knocking protocol. In this research, we implement OTP S/Key protocol, combined with Diffie Hellman Key Exchange (DHKE), to supply a knock sequence that changes every time it is used, thus preventing knock sequence retransmission or also known as replay attacks. By comparing the intercepted port sequence of the standard port knocking protocol and the proposed protocol, it is concluded that OTP S/Key and DHKE can prevent replay attacks in port knocking.

27/11/2018

978-602-53524-0-9

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