NTP on Router or Raspberry Pi

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Bugsysiegals
DD-WRT Novice


Joined: 15 Apr 2018
Posts: 40

PostPosted: Thu Nov 29, 2018 21:41    Post subject: NTP on Router or Raspberry Pi Reply with quote
I've recently connected security cameras to my network which require NTP to keep time. I'd prefer to limit the open ports on my router and therefore would like to install and run NTP locally.

Would it be better to connect a Raspberry Pi 3 and run NTP and perhaps other optware/entware software on it rather than installing NTP on the router itself?
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jxm
DD-WRT Guru


Joined: 23 Jul 2017
Posts: 706
Location: Brisbane, Australia

PostPosted: Fri Nov 30, 2018 3:14    Post subject: Reply with quote
You really should not need to open a port to allow devices on your LAN to access NTP servers. On the WAN. Your security system controller should be able to connect any NTP server on the WAN to synchronise its clock without changing any router setting, the same way all your comuters do. Wouldn't the controller / recorder overlay its time on the recordings for all the cameras?

You can run an NTP server on your router... there are links in this thread that should help you with that.
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=290375&sid=39003e15d9ffa6378907e0ec3041e8cc

If you run a Time Server on a Raspberry Pi you would be able to synchronis it with any NTP server on the WAN, or I imagine you could use an attached GPS capable device.

Cheers
d0ug
DD-WRT Guru


Joined: 31 Jul 2015
Posts: 758

PostPosted: Fri Nov 30, 2018 15:07    Post subject: Reply with quote
jxm wrote:
You really should not need to open a port to allow devices on your LAN to access NTP servers. On the WAN. Your security system controller should be able to connect any NTP server on the WAN to synchronise its clock without changing any router setting, the same way all your comuters do. Wouldn't the controller / recorder overlay its time on the recordings for all the cameras?

You can run an NTP server on your router... there are links in this thread that should help you with that.
https://forum.dd-wrt.com/phpBB2/viewtopic.php?t=290375&sid=39003e15d9ffa6378907e0ec3041e8cc

If you run a Time Server on a Raspberry Pi you would be able to synchronis it with any NTP server on the WAN, or I imagine you could use an attached GPS capable device.

Cheers


Some cameras can overlay time and other info in the video stream directly from the camera. The IP based security cameras that I use can do this.

I personally would not run an NTP server on either a router or a PI. Neither have an real time clock chip and the time will drift significantly over time if the router or pi doesn't keep its own time synced with an external NTP server.

I'd suggest just pointing the cameras time sync at pool.ntp.org As said previously, you shouldn't need to open up any ports on your router for them to communicate to an external ntp server.

If you really want an NTP server that exists in isolation from the internet, i can suggest the link below. I have set one of these up myself. I have a PC based server that syncs it's time to the GPS NTP server that I setup, and all the other devices on my network sync time off the NTP server running on that server. http://absolutelyautomation.com/articles/2016/09/15/esp8266-based-wireless-ntp-server-no-internet-connection-needed
Bugsysiegals
DD-WRT Novice


Joined: 15 Apr 2018
Posts: 40

PostPosted: Fri Dec 07, 2018 14:06    Post subject: Reply with quote
I have my IP Cameras connected to a PoE switch which then connects to a NIC on a PC which manages recording. The PC connects to a port on my router from another NIC. AFAIK, this firewalls the cameras from accessing anything on the internet but allows me to still access the cameras through Blue Iris software.

I've seen the PC making a lot of outbound connections on port 8888 so I've now blocked the PC except from gmail, port 123 NTP, and OpenVPN.

What I really want to do is point the cameras to the PC to get their time, which is overlaid in the video, and allow the PC to get the time from the internet. Perhaps the links you've shared will allow this, I'll have to check ... thanks!
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