Tag: NTP

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Explaining NTP

Time synchronization is an often overlooked concept in computer networking. The Network Time Protocol, also just shortened to NTP, is a network protocol and standard that allows distributed computers to synchronize their time.

Why is this important? Keeping proper time on computers, particularly when dealing with several computers communicating with each other, is important for things such as logging data and tracing of activity. On an NVR, perhaps the most important aspect is that of file system accuracy. Knowing when files were written or read is important to verify the when the activities in recorded video took place, as well as to perform forensic searches. Computer systems also need to know which version of files are most current for syncing files and performing file recovery. Time is also used by operating systems for many security and management controls, such as when using Active Directory/LDAP.

NTP consists of different tiers, originating from extremely accurate atomic clocks. These tiers are referred to as “stratum,” and measure the distance between systems in each tier and the atomic clocks in the top-most tier, deemed to be officially accurate. As the stratum number increases, the confidence of being synched to the most official time decreases. Primary time servers, such as time.nist.gov, pool.ntp.org, time.windows.com, time.google.com, and many others, are in Stratum 1.

When enabled, an NTP client like the NVR running your ExacqVision Server, begins a request from the NTP server.

Your system then automatically calculates the delay in the network link and uses the offset time (the offset time is based on the time zone setting you choose) and adjusts its own clock to the correct time and date.

If your system time is much different from the NTP source when this begins, it may take 5-10 minutes and several of these exchanges with the NTP source to initially bring the system clock into alignment with the NTP source. Once your system is synchronized it will continue checking for updates about every 10 minutes.

If you are experiencing problems communicating with an NTP source on the internet, you may need to investigate your firewall or antivirus settings. The exchanges made by the NTP protocol utilize UDP on Port 123.

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How to check the Stratum level used on Windows

  1. Open a CMD window to reveal a CLI prompt.
  2. Enter the following command:
    C:\Windows\System32\w32tm.exe /query /status
  1. The stratum level can be seen on the second line of the results. The following example:

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How to check the Stratum level used on Linux (Ubuntu)

  1. Open a Terminal window to reveal a CLI prompt.
  2. Enter the following command:
    ntpq -c rv
  1. The stratum level can be seen on row three of the results, as pictured in the example below:

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Panasonic cameras OSD incorrect after Server time change

Issue:

After a Server time change of less that 60 seconds, Panasonic cameras may continue to show the OSD time incorrectly until the camera is disconnected/reconnected.

The stored video also contains the incorrect time-stamp. This means the searched video will be off by the amount of seconds that they system time changed.

Workaround:

Disconnect and reconnect the camera on the Add IP Cameras page.

Fixed In:

Dev 21.06.108
Expected in public release 21.09.

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Knowledge Support Support Categories Products exacqVision Integrations

Verifying NTP on Linux system (8.04)

I verified the following in my Ubuntu 8.04 VM. So, hopefully should also be accurate for a natively-installed system.

1 – Verify that ntpd is running:

            ps -Af | grep ntp

            sudo netstat -nap | grep ntp

            Verify that ntpd is running and listening on port 123.

2 – Verify the following lines within /etc/ntp.conf:

            server 127.127.1.0

            fudge 127.127.1.0 stratum 13

            There may be an additional server line preceding these lines, depending on whether the user has used eV to configure NTP.

3 – Start ntpd if not already started:

            sudo /etc/init.d/ntpd start

            Then use ps to verify that ntpd is running – don’t just assume so because initscript didn’t display any errors.

4 – Test NTP server with local command-line client:

            sudo ntpdate -q localhost

            The “-q” means just query, don’t change anything.

            You will likely get initial output resembling:

                  server 127.0.0.1, stratum 16, offset -0.000007, delay 0.02563

                  23 Feb 13:39:57 ntpdate[12987]: no server suitable for synchronization found

            After nearly 5 minutes (perhaps less, but definitely more than a couple), you’ll start getting output resembling:

                  server 127.0.0.1, stratum 14, offset -0.000006, delay 0.02563

                  23 Feb 13:43:57 ntpdate[13001]: adjust time server 127.0.0.1 offset -0.000006 sec

The apparent necessary delay in #4 above was *really* interesting.

So first, it appeared that ntpd was NOT running on the customer’s system, so we started it while I was at Gary’s desk. Then, you tried rebooting the Axis camera, but got the ntp failure in the camera’s log. I suggest allowing up to 5 minutes, verify on the Linux system itself with ntpdate as I described above, and then if that looks good, THEN reboot the Axis camera and see if you get better results in the camera’s log.

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Sony generates excessive configuration events with invalid ntp server

Description

sony generates excessive configuration events with invalid ntp server

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Version Introduced

v3.3.3.15350

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Steps to reproduce

enable an ip camera time server override with characters requiring url encoding

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Expected result

time server override value is set in camera

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Actual result

plugin continuously fails to update camera

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Work Around

configure the ntp server using the camera’s web interface

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Version Fixed

none

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Keywords

Sony NTP

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User Guides exacqVision Server Categories Products

exacqVision Edge Time Zone Configuration

exacqVision Edge is a version of exacqVision Server that runs directly on supported camera models and only connects to, and records video from, the camera it is hosted on. Cameras running the exacqVision Edge, or Edge+, application must be configured for the GMT+0 time zone.

Because the server application runs directly on the camera, the Time Zone field cannot be configured from a connected exacqVision Client, but will need to be configured through the camera’s web browser interface.

However, the Time and Date fields can be configured from within the exacqVision Client and should be configured to GMT+0 rather than the current time where the camera is located.

Because the server application is running directly on the camera, the application tells the camera to use the loopback address of 127.0.0.1 as its time source, effectively telling the camera to look to itself for its time. Enabling the Time Server setting will not correct this. But you may override this behavior by selecting the Enable Override option and entering the URL or IP address of an NTP source of your choice. This will override the localhost setting, forcing the camera to use a trusted network time source. For more information on NTP sources, refer to Explaining NTP.

The below example, from an Illustra camera, illustrates that the Time Zone will be set to GMT+0 in the camera. You will need to restart the Edge Server application on the camera if changing this after it has started.

When connecting the exacqVision Client to an exacqVision Edge Server instance, the Client will display the time of the client workstation in the OSD unless you configure the OSD to display Timezone information, in which case it will display the camera’s time of GMT+0.

The two example images below illustrate this effect. With the Timezone checked, the client time shown in the bottom-right of the window’s status bar is reflected in the camera OSD time. When the Timezone field is unchecked, the camera OSD time will match GMT+0 rather than the local client time.

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Time Settings and Time Zone Information

Background Information

The Windows or Linux (Ubuntu) operating system time of your exacqVision Server host should be set to the local time and time zone where it is located.

It is often desirable to synchronize the system to a central time server, rather than rely on the internal clock of the recording server. There are many freely available time servers available online capable of providing reliable time references, such as:

  • pool.ntp.org
  • time.google.com
  • time.windows.com
  • time.nist.gov

These time servers communicate using the Network Time Protocol (NTP), using network port 123. For more information about network time servers, refer to the article Explaining NTP.

If your system is on an isolated network without access to the internet, or you prefer to provide your own source for time, many SOHO routers provide NTP capabilities, or you may choose to run an NTP service on another device or system of your own. <br><br>

Best Practice Configuration Steps

  1. With the exacqVision Desktop Client connected to your exacqVision Server instance, navigate to the Configure System node on the navigation tree along the left, then select the Date/Time tab from the top of the page.

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  2. The URL or IP address of the time server you choose to use will be entered into the Time Server field after checking the Enable Time Server checkbox. If the Enable Time Server box is left unchecked, the system will rely on its internal clock, which is not as reliable as the NTP sources mentioned above. <br><br>
  3. Your networked IP cameras should be synchronized to the time and date of the exacqVision Server. While it seems counterintuitive, you will log into your cameras to configure their time settings and set them to the GMT-0 time zone. Then enter the IP address or URL of your exacqVision Server as the Time Server in the camera’s settings.

    This will ensure that video sent to the exacqVision Server is recorded with a time code in reference to the Server time. For this reason, it is recommended to use the exacqVision Client’s on-screen display (OSD), to display the time and date overlay on your live video panels. If enabling the OSD within the camera instead, your time and date may display incorrectly because the exacqVision software has not accounted for your local time zone difference from GMT.<br><br>
  4. The IP Camera Time Server field shown at the bottom of the Date/Time tab within the exacqVision Client is not commonly used for most deployments. Enabling the override feature allows an administrator to enter the URL or address of another time server. The exacqVision Server will then inform connected IP cameras to refer to the entered address as it’s “source of truth” for time, rather than using the time shown on the exacqVision Server.

    NOTE: If using this feature, the cameras will require a network path to reach any address entered here, which may not be possible if your cameras reside on an isolated network or VLAN. <br><br>

Client Workstations

Client workstations running the exacqVision Client application should be configured to use the local time and time zone where they are located.

If they are remote users in a different time zone than the exacqVision Server, all times for live and searched video will be displayed in the client’s local time.

All video recorded by exacqVision is timestamped in Coordinated Universal Time, also known as UTC, so there is no ambiguity as to the absolute time when the video was recorded. In the exacqVision Client, the OSD display shows the server time zone as an offset from UTC with the timestamp. If the timezone is not configured for the OSD, the timestamp shown is the Client’s local time.

exacqVision ePlayer

Within the exacqVision ePlayer, the timestamp of the recorded video will display the timezone of the local computer on which it is playing, but will also show the time zone offset.

As an example, if you watch a video on a computer set to Eastern Daylight Time, you could see 9:00am (GMT-4:00), while the same video viewed on a computer set to British Summer Time would show 2:00pm (GMT+1:00). The UTC timestamp is the same in both cases.

Knowledge of the physical location of the recording server, which may be needed for evidentiary purposes, can be correlated to the local time of the machine on which video is being watched and the local time of the server on when it was recorded.<br><br>

exacqVision Edge/Edge+

This article applies to exacqVision Server software. For information on exacqVision Edge/Edge+ time settings, please refer to exacqVision Edge Time Zone Configuration.

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