Book Image

Mastering pfSense - Second Edition

By : David Zientara
Book Image

Mastering pfSense - Second Edition

By: David Zientara

Overview of this book

pfSense has the same reliability and stability as even the most popular commercial firewall offerings on the market – but, like the very best open-source software, it doesn’t limit you. You’re in control – you can exploit and customize pfSense around your security needs. Mastering pfSense - Second Edition, covers features that have long been part of pfSense such as captive portal, VLANs, traffic shaping, VPNs, load balancing, Common Address Redundancy Protocol (CARP), multi-WAN, and routing. It also covers features that have been added with the release of 2.4, such as support for ZFS partitions and OpenVPN 2.4. This book takes into account the fact that, in order to support increased cryptographic loads, pfSense version 2.5 will require a CPU that supports AES-NI. The second edition of this book places more of an emphasis on the practical side of utilizing pfSense than the previous edition, and, as a result, more examples are provided which show in step-by-step fashion how to implement many features.
Table of Contents (15 chapters)

NTP

NTP is an application layer protocol that controls the synchronization of various devices over the internet to within a few milliseconds of Coordinated Universal Time (CUT). NTP is hierarchical, with servers organized into different strata. At stratum 0 are high-precision time devices such as atomic clocks. At stratum 1 are computers that are synchronized within a few microseconds to their directly connected stratum 0 devices. At stratum 2 are computers that are directly connected to stratum 1 computers, and so on. Synchronization is achieved by adjusting the system time based on an offset. The offset is calculated by taking an average of the differences of the timestamps on request and response packets between the client and the server. The clock frequency is then adjusted to reduce the offset gradually, and the newly adjusted clock provides timestamps for the next request...