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how to book ccna 200-301 exam.12.3 Security Monitoring and Network Address TranslationChapter 2 covered in depth the network address translation (||) capabilities that Layer 3 devices (e.g., routers and firewalls) have. A router or firewall can "convert" the private (or real) IP address of an "internal" host to a routable public (or mapped) IP address. A NAT-enabled firewall hides internal private addresses from networks not protected by it, and exposes only external (public) addresses or address ranges that are set locally. Network administrators can use any IP address space as the unit's internal address space. Best practice is to use the IP address space reserved for private use (see RFC1918, wAddress AllocationforPrivate Internets" for details).Note: In the Cisco documentation for NAT, the terms real and mapped IP addresses are used. A real IP address is a host-based IP address that has not been translated. A mapped IP address is a 1P address after the real address has been translated.Static NAT supports bidirectional initiation of connections, that is, internal hosts can either initiate connections or receive connections initiated by external hosts.When performing security monitoring tasks, analyzing logs, NetFlow, and other data, you may face difficulties caused by NAT because the IP address of the device presented in the logs may be a "translated" IP address rather than a "real" IP address. IP address. The situation can become even more problematic with port address translation (PAT), as the IP addresses of many hosts can be converted to a single IP address, making log management nearly impossible.Some security products, such as the Cisco Lancope Stealthwatch system, have the ability to associate and correlate converted IP addresses with NetFlow data. This capability, called NAT stitching, is available on Cisco Lancope Stealthwatch systems. o This capability not only helps speed up security incident response, but also eases ongoing security monitoring and maintenance efforts.12.5 DNS Tunneling and Other "Data Entrainment" Methods 46112.4 Security Monitoring and Event Correlation Time Synchronization,,II ..... As mentioned in Chapter 11, server and endpoint logs, NetFIow, syslog data, and any other security (JI monitoring data is useless as long as the date and time are incorrect. That is why it should be considered a best practice to turn on the Network Time Protocol (NTP) feature for all network devices so that these devices are timed to the same reference clock source.Turning on the NTP feature ensures that network devices have the correct time, and it keeps all devices within the network in time synchronization. In addition, another best practice is to strive to keep the number of duplicate logs to a minimum. Because of this, it is important to think ahead and plan exactly where to deploy NetFlow, how to correlate it with other events (e.g., Syslog), and so on.