\chapter{NTP} \gls{ntp} is the source of all evil and \gls{sla}. A network wide source of time configuration for all network nodes, servers, clients etc. is necessary. \textbf{Configure timezone}\\In this case it\tsq{s} for \gls{metdst}\textbf{:} \begin{txt} clock timezone MET 1 0 clock summer-time MET-DST recurring last Sun Mar 2:00 last Sun Oct 3:00 \end{txt} \textbf{Configure used timezone}\\when doing logging and debugging operations\textbf{:} \begin{txt} service timestamps debug datetime msec localtime show-timezone service timestamps log datetime msec localtime show-timezone \end{txt} \fig{ntp/ntp}{ntp}{\gls{ntp}} \gls{ntp} servers are a hierarchical tree with stratum 0 servers as the authoritative in the tree. These servers get their time from either \gls{gprs} satellites or atomic clocks {\footnotesize (i.e. an authoritative time \gls{src})}. \subsection{Characteristics} \begin{itemize} \item Uses \gls{udp} port 123 on both \gls{src} and \gls{dst}, \item polling interval ranging from 64-1024 sec. Length of interval is dependant upon network cond., \item large differences between \gls{ntp} reference time and local client time will result in increased pooling interval. \end{itemize} \fig{ntp/ntpstratum}{ntpstratum}{Stratum levels} \section{The old NTP from \tsq{85}} \section{Secure NTP} \subsection{Characteristics} \begin{itemize} \item \end{itemize}