Port-knocking is a security mechanism used in computer systems to hide available network services. Its operation relies on a drop policy firewall setting in order to make impossible for port-scanning attacks to occur. This project researches the impact of implementing such a software solution. Furthermore, it looks into the behavior of three chosen implementations and make conclusions on the benefits and disadvantages that they bring. In addition, the surrounding implications related to both user and administrator are explored. This thesis includes tests on the resource consumption of the implementations as well as records of the added delay of using the mechanism when initiating a SSH session. There has not been such research performed in this field and the results of it could be beneficial to those who are involved in computer science and network security in particular. Finally, the product of this study state that port-knocking is overlooked and has great benefits in preventing zero-day exploits and hacker tools relying on exposed network services.