446 ITU‐T's Technical Reports and Specifications In the firewall‐centered security environment, all security measures (e.g. passwords, encryption, authentication and auditing, among others) can be configured on the firewall. This approach is more cost‐effective than a decentralized network security mode. If all network accesses go through the firewall, this can record and make a log of these visits, and also provide statistical data of network usage. When suspicious actions occur, the firewall can then generate the appropriate alarm, and provide detailed information about the incident for threat analysis purposes. Protecting intrusion dynamically Intrusion detection is another important dynamic security technology, which can collect and analyze information from a number of key points of computer network and system, and find out whether there is any suspicious behavior, sign of an attack or policy violation. There are three types of intrusion detection systems (IDSs): (a) network‐based IDS; (b) host‐based IDS; (c) integrated IDS. Preventing DDoS attacks There are different mechanisms that can enhance the ability to withstand DDoS through increasing the cost of attack. These include the use of high‐performance network equipment, the guarantee of sufficient network bandwidth, the upgrade of the host server hardware, the use of static pages whenever possible, the enhancement of the operating system transmission control protocol (TCP)/IP stack, and the installation of specialized anti‐DDoS firewall. Network security audit A network security audit carries out compliance management by fine‐grained auditing the network operating behavior of the business environment. Through recording, analyzing, and reporting the network behavior of system and authorized users, the network security audit can function as a mechanism for planning and preventing, concurrently monitoring, as well as reporting and tracking the source after the incidents take place. Consequently, network security audits can strengthen the internal and external networks behavioural regulation. Child online protection in SSC As the analysis conducted thus far has demonstrated, the design of a comprehensive cybersecurity strategy for SSC should take into account multiple sources of vulnerabilities, as well as existing and emerging threats. Children are among the most vulnerable users of online services. As identified by the ITU‐T Joint Coordination Activity on Child Online Protection (ITU‐T JCA‐COP): \"Child online protection covers a number of issues, and is being addressed at national, regional and international levels, across a myriad of environments, including social and legal. At the international level, and within the ITU, the Council Working Group on Child Online Protection has received much information on national activities, and has developed guidelines, and the Joint Coordination Activity on Child Online Protection has identified many technical activities that are contributing to the safety of children on line at a global level.\"(ITU‐T JCA‐COP) Further details about child online protection can be found in the reports produced by the ITU‐T JCA‐COP, at http://www.itu.int/en/ITU‐T/jca/COP/Pages/default.aspx.