The 5G security function is a proposed upgrade of the currently inadequate software architecture of 5G networks. It contains Firewall, Intrusion Detection and Intrusion Protection systems including the clever Intrusion Detection System (IDS) which is able to identify many of the attacks to which 5G systems at present can be extremely vulnerable. With the proposed systems many of these software attacks can be much more quickly identified. This is an important advance given that the world’s telecommunications industry is undergoing a fundamental transformation towards 5G networks.