NTS2-GPS-USB Network Time Source System Manual

Transcription

1 NTS2-GPS-USB Network Time Source System Manual Red Herring Ltd. 2015

2 Document History Issue Date Comments January-2015 Based on nts1-gps manual June-2015 Add syslog information September-2015 Change user info

3 Contents 1. Introduction Overview Time and NTP Web Interface GPS NMEA 5 2. Installation and Configuration Unpacking Initial Configuration Logging into the NTS2-GPS-USB For The First Time Changing The Password Changing the Network Configuration Reset to Factory Defaults 9 3. Web User Interface Time Functions Status NTP Peers NTP Clients NTP Restart ntpd Edit ntp configuration Edit ntp MD5 keys Reset ntp configuration to factory default Diagnostics NMEA Satellites DNS resolver Ping Syslog Admin Network configuration Password modification System Reboot Additional Functions Firmware Upgrade 19

4 Document Purpose The purpose of this document is to provide. Instructions for installation of the NTS2-GPS-USB time source. Operator instructions for usage. Firmware upgrade process References [1] Ntpd. See documents at [2] NMEA. See DISCLAIMER Due to the simplicity of the construction of the NTS2-GPS-USB time source it will provide a time reference as best it can based on the reception of NMEA data and the drift of its local clock oscillator. The NTS2- GPS-USB is not designed nor intended for use in application where high-precision UTC time is required. Position information is provided by the NTS2-GPS-USB for reference only, it is not to be used for precise positioning. By using the NTS2-GPS-USB you absolve Red Herring Ltd from any liability for its use. Red Herring Ltd is not responsible for any dispute on time synchronisation or positioning when using the NTS2-GPS-USB nor is responsible or liable for its use. Use of the NTS2-GPS-USB for time synchronisation for mission-critical, healthcare, defence, aerospace or commerce applications where a high-precision ultra-stable time reference is requires is not countenanced by Red Herring Ltd.

5 1. Introduction 1.1 Overview The Red Herring NTS2-GPS-USB is a linux-based computer which utilises open-source ntpd [1] software and a USB GPS receiver to provide a network time source. NMEA [2] sentences are read from the GPS receiver via USB and the time-stamp information within this NMEA is used to discipline the local hardware clock. The unit operates as a Web Appliance - control of the unit is provided by a web interface which allows an operator to monitor the time-source, change ntp configuration files and alter the platform settings (e.g. IP address etc.). It is not necessary to ssh to the NTS2-GPS-USB to configure or control it. In addition to time synchronisation the GPS NMEA data is used to provide position information (although this is for reference only). The unit can be configured for static-ip addressing or DHCP. 1.2 Time and NTP The NTS2-GPS-USB run the standard ntpd daemon (currently ntp version 4.2.8) configured to use a local GPS NMEA reference clock. The use of the GPS NMEA allows the local system clock to be disciplined so that it stays in synchronisation with UTC system time. As the local system clock is not a temperature controlled high-precision oscillator there is some minor drift of the clocks time over the course of 24 hours. Time from ntpd is served to any network device requesting it from the NTS2-GPS-USB. Ntpd is configured to run with MD-5 keys for time authentication. 1.3 Web Interface The NTS2-GPS-USB provides a standard html interface on http on port-80. This interface is protected with a challenge-response username-password. This interface provides web pages for System and NTP status. Ntpd configuration and control. Diagnostics. Platform management, configuration and control. 1.4 GPS NMEA Local clock discipline is provided by using time-stamp data from GPS NMEA data [2]. The NMEA sentences (a stream of satellite information encoded into text) are provided by the GPS receiver over the USB connection and these are read and utilised by ntpd. The NMEA can be viewed for diagnostic purposes using the unit s web interface.

6 2. Installation and Configuration 2.1 Unpacking The unit comprises One NTS2-GPS-USB compute platform One GPS USB receiver One UK power-supply Connect the NTS2-GPS-USB to a network connection, plug in the USB GPS to the any USB port (this must be done prior to powering on the unit). Connect the mains-power to the unit and it will boot, after approximately seconds the NTS2-GPS-USB will be ready and will use the GPS receiver to search for satellites to provide time synchronisation. Place the GPS receiver in an area when it can get a clear view of the sky e.g. a window-cill or externally. For a first boot (GPS cold-start) it may take some minutes before the GPS receiver sends stable NMEA data so that time can be synchronised. The green LED on the front panel of the nts2-gps-usb is illuminated when the unit obtains time synchronisation from the satellites. 2.2 Initial Configuration The initial unit configuration is as follows Network address Netmask Gateway DNS , (Open DNS public DNS server) Web interface username Web interface password Web and SSH username Password ntpuser ntpuser ntpadmin ntpadmin The ntpadmin user can be used to log into both the web interface and SSH to the platform.

7 2.3 Logging into the NTS2-GPS-USB For The First Time Browse to with a web-browser (e.g. internet explorer, Mozilla firefox, Chrome etc). A username/password challenge-response box will be displayed : Enter admin for the username, admin for the password and click OK. The following screen will be presented 2.4 Changing The Password Click the Passwords link (in the Administration section of the left-hand navigation) and the change password page is displayed. The password for the account admin can be changed.

8 If the password is lost or forgotten it can be reset to the Initial Configuration settings (Section 2.2) by rebooting the nts2-gps-usb with the USB GPS receiver unplugged. (See Section 2.6)

9 2.5 Changing the Network Configuration Click the Network link under the title Admin, and the following screen will be presented: The network configuration can be altered and it is saved when the update button is clicked. The unit can be switched to DHCP (dynamic IP addressing) or static-ip addressing on this page. The NTS2-GPS-USB must be rebooted before the new settings take effect. If an error is made in the network configuration the unit can be reset to the Initial Configuration settings (Section 2.2) by rebooting the device with the USB GPS receiver removed (See Section 2.6) 2.6 Reset to Factory Defaults Errors in the network configuration or if the unit s password are forgotten the unit can be reset to factory default settings as follows Power down the NTS2-GPS-USB Remove the USB GPS receiver from the USB port Reboot the unit The unit will reset its networks settings and passwords as per the Initial Settings section (Section 2.2): Network address Netmask Gateway DNS , (Open DNS public DNS server) Web interface username Web interface password Web and SSH username Password ntpuser ntpuser ntpadmin ntpadmin

10 3. Web User Interface The web interface is divided into four sections Time functions NTP Configuration functions Diagnostic functions Platform administration functions 3.1 Time Functions Status This page shows the overall status of the NTS2-GPS-USB

11 3.1.2 NTP Peers This page displays the output of ntpq p which shows the status of NMEA clock for ntpd NTP Clients Previous versions of the NTS2-GPS-USB firmware allowed a list of clients synchronising to the unit to be displayed. Due to security issues this feature has been disabled in the ntpd software, and, subsequently in the NTS2-GPS-USB firmware. 3.2 NTP Restart ntpd This page allows control of the ntpd daemon. Ntpd can be stopped and started using this page.

12 3.2.2 Edit ntp configuration This page displays the ntp.conf used by the Ntpd daemon. The contents of this file can be edited and updated. The ntpd daemon will need to be restarted for the changes to take effect Edit ntp MD5 keys The Ntpd daemon uses MD5 keys for ntp authentication [1]. These MD5 can be edit or replaced using this page.. The ntpd daemon will need to be restarted for the changes to take effect.

13 3.2.4 Reset ntp configuration to factory default Should the ntp.conf configuration become corrupted it can be reset to factory defaults using this page. 3.3 Diagnostics NMEA This page shows a sample of the NMEA data received by the NTS2-GPS-USB. This data is updated every five minutes.

14 3.3.2 Satellites This page shows the current satellites which are in view and their signal strengths. This data is updated every five minutes.

15 3.3.3 DNS resolver This page allows an nslookup to be performed on a host name or IP address. The IP address of the DNS server must be configured correctly in the network settings for this to work.

16 3.3.4 Ping This page allows a host name or IP address to be pinged to test network connectivity.

17 3.3.5 Syslog This page allows syslogd to be enabled/disabled and the host name or IP address and port number for logging to be specified. Syslogd allows log information from the nts2-gps-usb to be sent to a logging server over the network. 3.4 Admin Network configuration This page allows the network configuration for the unit to be changed. The unit must be rebooted for the changes to take effect.

18 3.4.2 Password modification This page allows modification of the password for the users ntpuser and ntpadmin System Reboot This page allows reboot of the unit to take place.

19 4. Additional Functions 4.1 Firmware Upgrade This page allows firmware of the unit to be upgraded. The firmware must first be obtained from Red Herring Ltd. The user then clicks Choose File and selects the firmware file. The user then clicks Upgrade and the unit will upgrade itself. The unit must not be powered off during this time. The success or failure of the upgrade is indicated to the user.