thanks David R1, if the VPN option( ipsec, OpenVPN will work this solution, but do you have in mind the kind of router to use for this ?
Well to be able to monitor and playback without going to the office and no one should have access to the NVR.
Your best bet is always whatever you or your IT staff is familiar with - you may even have the ability to use the equipment you already have depending on what it is. I don't use consumer products for the PTP connections I manage so I wouldn't be able to recommend something affordable and "off the shelf" if that's really something you want to pursue. If you don't have the expertise in-house, then your best bet is a consultant (who will probably also tell you this isn't ideal, unless they're happy just making a buck on the initial configuration.)
you know an additional 4 cameras are installed at office B and is connected to the NVR and there are free 4port that is why i want deploy this solution
I understand the desire for cost-savings. I think in the long run, you'll save yourself money and hassle just getting a second NVR for office A. Some other things to consider:
- Cameras at office A need to be powered somehow.
- Cameras at office A need network connectivity.
- Cameras at office A need to store video somewhere.
An NVR for each site seems like the ideal solution if you want to keep things simple. That's just my opinion though.
As for worrying about people accessing the NVR, they also shouldn't access your network equipment; presumably that equipment is secured somehow? If so, that same location would be an ideal place for your NVR (which should also be kept cool, on a UPS, etc. just like other network and computer gear.) Also, please realize that you're talking about building a solution where the network (including pieces completely beyond your control) is an integral part at all times - not just for monitoring and playback.
If you just want to monitor and playback without traveling to an offsite location, then you really you should record on site, and use a VPN only for viewing video as needed. Then it doesn't matter if there are temporary problems with your provider at either location or on the open Internet. You can view lower quality feeds remotely the majority of the time to reduce bandwidth requirements, while still having full quality available on site to be accessed when needed.