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Merge branch 'feature/ntp' into develop
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commit
e1edcb060a
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.gitignore
vendored
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main\.glsdefs
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main\.synctex\.gz\(busy\)
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13
acronyms.tex
13
acronyms.tex
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@ -14,29 +14,35 @@
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\newacronym{cdp}{CDP}{Cisco Discovery Protocol}
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\newacronym{cli}{CLI}{Command Line Interface}
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\newacronym{cst}{CST}{Common Spanning Tree}
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\newacronym{cest}{CEST}{Central European Summer Time}
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\newacronym{cwdm}{CWDM}{}
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\newacronym{db}{DB}{Database}
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\newacronym{dhcp}{DHCP}{Dynamic Host Control Protocol}
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\newacronym{dknog}{DKNOG}{Danish Network Operators' Group}
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\newacronym{dns}{DNS}{Domain Name System}
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\newacronym{dst}{DST}{Destination}
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\newacronym{dst}{dst}{destination}
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\newacronym{dwdm}{DWDM}{}
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\newacronym{eap}{EAP}{Extensible Authentication Protocol}
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\newacronym{eapol}{EAPOL}{Extensible Authentication Protocol over Local Area Network}
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\newacronym{eapol}{EAPoL}{Extensible Authentication Protocol over Local Area Network}
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\newacronym{eigrp}{EIGRP}{Enhanced Interior Gateway Routing Protocol}
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\newacronym{erspan}{ERSPAN}{Encapsulated Remote Switch Port Analyzer}
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\newacronym{evpn}{EVPN}{Ethernet Virtual Private Network}
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\newacronym{ftp}{FTP}{File Transfer Protocol}
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\newacronym{ftps}{FTPS}{File Transfer Protocol Secure}
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\newacronym{gps}{GPS}{Global Positioning System}
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\newacronym{gprs}{GPRS}{General Packet Radio Service}
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\newacronym{gsm}{GSM}{Global System for Mobile communications}
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\newacronym{ieee}{IEEE}{Institute of Electrical and Electronics Engineers}
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\newacronym{igrp}{IGRP}{Interior Gateway Routing Protocol}
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\newacronym{imap}{IMAP}{Internet Message Access Protocol}
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\newacronym{ios}{IOS}{Internetwork Operating System}
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\newacronym{ip}{IP}{Internet Protocol}
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\newacronym{ipv4}{IPv4}{Internet Protocol v4}
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\newacronym{ipv6}{IPv6}{Internet Protocol v6}
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\newacronym{irc}{IRC}{Internet Relay Chat}
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\newacronym{isis}{IS-IS}{Intermediate System to Intermediate System}
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\newacronym{isp}{ISP}{Internet Service Provider}
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\newacronym{junos}{JUNOS}{Juniper Network Operating System}
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\newacronym{l2}{L2}{Layer 2}
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\newacronym{l2vpn}{L2VPN}{Layer 2 Virtual Private Network}
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\newacronym{l3}{L3}{Layer 3}
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@ -45,6 +51,7 @@
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\newacronym{lldp}{LLDP}{Link Layer Discovery Protocol}
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\newacronym{mac}{MAC}{Media Access Control address}
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\newacronym{mkc}{MKC}{Mikkel Kr\char"00F8ll}
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\newacronym{metdst}{MET-DST}{Middle European Time Daylight Saving Time}
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\newacronym{mpls}{MPLS}{Multiprotocol Label Switching}
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\newacronym{mst}{MST}{Multiple Spanning Tree}
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\newacronym{nms}{NMS}{Network Management Software}
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@ -72,7 +79,7 @@
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\newacronym{sntp}{SNTP}{Secure Network Time Protocol}
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\newacronym{sp}{SP}{Service Provider}
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\newacronym{span}{SPAN}{Switch Port Analyzer}
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\newacronym{src}{SRC}{Source}
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\newacronym{src}{src}{source}
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\newacronym{ssh}{SSH}{Secure Shell}
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\newacronym{stp}{STP}{Spanning Tree Protocol}
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\newacronym{tcn}{TCN}{Topology Change Notification}
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@ -1,6 +1,97 @@
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\chapter{Network Time Protocol}
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\chapter{NTP}
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\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.
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\textbf{Configure timezone}\\In this case it\tsq{s} for \gls{metdst}\textbf{:}
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\begin{txt}
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clock timezone MET 1 0
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clock summer-time MET-DST recurring last Sun Mar 2:00 last Sun Oct 3:00
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\end{txt}
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\textbf{Configure used timezone}\\when doing logging and debugging operations\textbf{:}
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\begin{txt}
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service timestamps debug datetime msec localtime show-timezone
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service timestamps log datetime msec localtime show-timezone
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\end{txt}
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A select number of Cisco switches support synchronization with the hardware clock, too. The standard is to only sync the software clock.\\\cliline{ntp update-calendar}
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\fig{ntp/ntp}{ntp}{\gls{ntp}}
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\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})}.
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\subsection{Characteristics}
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\begin{itemize}
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\item Uses \gls{udp} port 123 on both \gls{src} and \gls{dst},
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\item polling interval ranging from 64-1024 sec. Length of interval is dependant upon network cond.,
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\item large differences between \gls{ntp} reference time and local client time will result in increased pooling interval.
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\end{itemize}
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\fig{ntp/ntpstratum}{ntpstratum}{Stratum levels}
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\section{The old NTP from \tsq{85}}
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\textbf{Team Cymru} has a nice template for how to enable \gls{ntp} \textbf{with} \textit{access control} on \gls{ios} and \gls{junos}\footnote{\url{https://www.team-cymru.org/secure-ntp-template.html}}. Shown below is a copy of the \gls{ios} example from Cymrus website.
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\begin{cisco}
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! Core NTP configuration
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ntp update-calendar ! update hardware clock (certain hardware only, i.e. 6509s)
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ntp server 192.0.2.1 ! a time server you sync with
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ntp peer 192.0.2.2 ! a time server you sync with and allow to sync to you
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ntp source Loopback0 ! we recommend using a loopback interface for sending NTP messages if possible
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!
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! NTP access control
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ntp access-group query-only 1 ! deny all NTP control queries
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ntp access-group serve 1 ! deny all NTP time and control queries by default
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ntp access-group peer 10 ! permit time sync to configured peer(s)/server(s) only
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ntp access-group serve-only 20 ! permit NTP time sync requests from a select set of clients
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!
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! access control lists (ACLs)
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access-list 1 remark utility ACL to block everything
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access-list 1 deny any
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!
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access-list 10 remark NTP peers/servers we sync to/with
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access-list 10 permit 192.0.2.1
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access-list 10 permit 192.0.2.2
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access-list 10 deny any
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!
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access-list 20 remark Hosts/Networks we allow to get time from us
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access-list 20 permit 192.0.2.0 0.0.0.255
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access-list 20 deny any
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\end{cisco}
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\textbf{Beware} when running a cisco node as \gls{ntp} master and are using access-list to restrict possible clients/peers. You need to allow 127.127.[0-255].1 in the access-list\footnote{The 3rd octet will vary depending on the node.}. This because the master NTP node in the network uses this \gls{ipv4} address as internal master.
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\section{Secure NTP}
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\subsection{Characteristics}
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\begin{itemize}
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\item \gls{ntp} is insecure be default, whích prompted for \gls{sntp} to come along,
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\item Cisco \gls{ios} devices typically only support MD5 encryption\footnote{\url{https://en.wikipedia.org/wiki/MD5}}
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\end{itemize}
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\subsubsection{Configure SNTP}
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\textbf{Team Cymru} has a nice template for how to enable \gls{sntp} on \gls{ios} and \gls{junos}\footnote{\url{https://www.team-cymru.org/secure-ntp-template.html}}. Shown below is a copy of the \gls{ios} example from Cymrus website.
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\begin{cisco}
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ntp authenticate ! enable NTP authentication
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ntp authentication-key [key-id] md5 [hash] ! define a NTP authentication key
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ntp trusted-key [key-id] ! mark a NTP authentication key as trusted
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ntp peer [peer_address] key [key-id] ! form a authenticated session with a peer
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ntp server [server_address] key [key-id] ! form a authenticated session with a server
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\end{cisco}
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\subsection{Versions}
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Generally today \gls{ntp}v3 or v4 is found. The difference to v4 \textit{(amongst other)} is
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\begin{itemize}
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\item support for \gls{ipv6}.
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\item The security in the protocol is upped to with support for X509 certs.
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\item Automatic calculation of time-distribution\footnote{to archive high time accuracy against lowest bandwidth cost} in a network based upon specific multicast groups leveraging v6 site-local multicast addresses.
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\item \cliline{network-node(config)# ntp-server \textit{\gls{ipv6}-addr} version 4}
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\end{itemize}
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13
commands.tex
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commands.tex
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% Enviroment @var cisco
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\lstnewenvironment{cisco}{\lstset{language=cisco}}{}
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\lstnewenvironment{cisco}{\lstset{language=cisco}}{}
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%\newcommand{cisline}[1]{\lstinline[columns=fixed]{network-device\# #1}}
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%\newcommand{cisconf}[2][]{%
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%\def\temp{#1}\ifx\temp\empty
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%\lstinline[columns=fixed]{network-device(config)\# #2}
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%\else
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%\lstinline[columns=fixed]{network-device(config-#1)\# #2}
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%\fi\}
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BIN
img/ntp/ntp.png
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img/ntp/ntp.png
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img/ntp/ntpstratum.png
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img/ntp/ntpstratum.png
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@online{vtpchap4,
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author = {Hector Camba Lainez},
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title = {Cap4 implementing vtp},
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year = 2010,
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@online{ slideshare:vtpchap4,
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author = "Hector Camba Lainez",
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title = "Cap4 implementing vtp",
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year = "2010",
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url = {https://www.slideshare.net/lucky0679/cap4-implementing-vtp},
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note = {Last Accessed: 2017-05-22},
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note = "[Online; accessed 22-May-2017]"
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}
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@misc{wp_spanningtree,
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title = {Spanning Tree Protocol},
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year = 2017,
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url = {https://en.wikipedia.org/w/index.php?title=Spanning_Tree_Protocol&oldid=778662646},
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urldate = {2017-05-24},
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note = {Last Accessed: 2017-05-24},
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@misc{ wiki:Spanning_Tree_Protocol,
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author = "Wikipedia",
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title = "{Spanning Tree Protocol} --- {W}ikipedia{,} The Free Encyclopedia",
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year = "2017",
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howpublished = {\url{http://en.wikipedia.org/w/index.php?title=Spanning\%20Tree\%20Protocol&oldid=778662646}},
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note = "[Online; accessed 24-May-2017]"
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}
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@book{froom2015implementing,
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author = {Froom, Richard},
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title = {Implementing Cisco IP switched networks (SWITCH) : foundation learning guide},
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publisher = {Cisco Press},
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year = {2015},
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address = {Indianapolis, IN},
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isbn = {978-1-58720-664-1}
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author = "Froom, Richard",
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title = "Implementing Cisco IP switched networks (SWITCH) : foundation learning guide",
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publisher = "Cisco Press",
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year = "2015",
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address = "Indianapolis{,} IN",
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isbn = "978-1-58720-664-1"
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}
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\lstdefinelanguage{cisco}{
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keywords={
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access-list,
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cdp,
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dhcp,
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end,
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login,
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network,
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no,
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ntp,
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router,
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show,
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shutdown,
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},
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keywordstyle=\color{blue}\bfseries,
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ndkeywords={
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access-group,
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addr,
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address,
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aux,
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bgp,
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}
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\geometry{a4paper,margin=2cm}
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\geometry{a4paper,margin=1.5cm}
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\setlength{\columnsep}{1.5cm} %space between columns
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\setlength{\headheight}{15pt}
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\setlength{\footnotesep}{0.5cm} %space between footnotes:
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