Remote CCTV access terms, explained

Remote CCTV access means reaching a camera, a recorder or another device at a site from somewhere else, such as a control room. These are the terms you meet when you set it up, grouped by topic. Each one links to the page that covers it.

Networks and addresses

CGNAT: Carrier-grade NAT: the internet provider shares one public address between many customers. Nothing can be forwarded to a site behind it, and sites on 4G, 5G and Starlink are almost always behind it. A router internet address in 100.64.0.0/10 is a sign of it. See CGNAT and security cameras.
Static IP: A public internet address that does not change, usually a paid extra from the internet provider. With one, a router can forward a port to a device. Without one, see CCTV remote access without a static IP.
Dynamic DNS: A name that follows a site's changing public address, so you can reach its router by name. Behind CGNAT it has no address of the site's own to point at, so it does not work. See port forwarding and dynamic DNS.
Port forwarding: A rule on the site's router that sends traffic arriving on a public port to a device inside. It needs a public address and access to the router, and it puts the device's own login on the internet. It does nothing behind CGNAT. See port forwarding compared.
Subnet: A range of addresses that share one local network, such as 192.168.1.0 to 192.168.1.255. Devices on another subnet or VLAN are reached only if the network routes to them. See Installing the software agent.
VPN: A virtual private network: an encrypted tunnel that joins a computer or a network to another network over the internet. A site VPN usually needs a client, a server or router settings at each end. See remote.it compared.
Mesh VPN: A VPN where each device runs a client and a central service joins them into one private network. Tailscale and ZeroTier are examples; at a site they need a client per device, or an always-on computer that passes traffic on. See Tailscale and ZeroTier compared.
P2P cloud: A camera maker's service that lets its app reach the maker's own devices through the maker's cloud, without a port forward. It is used through the maker's app or portal. See camera makers' clouds compared and Dahua P2P offline.

Cameras and recorders

IP camera: A camera that connects to the network itself and sends its video over it, usually to a recorder or to monitoring software. See Hikvision remote access.
NVR: Network video recorder: a recorder that takes video from IP cameras over the network. Software usually reaches the cameras' video through it. See When an NVR shows offline.
DVR: Digital video recorder: a recorder that analogue cameras are cabled to directly. On the network it behaves like an NVR: one device with its own address and ports. See When an NVR shows offline.
ONVIF: An open industry forum and its standard interfaces, so IP security products from different makers work together. Our health checks can ask a device's ONVIF service whether it is alive. See Device health.
RTSP: Real Time Streaming Protocol: how software sets up and controls a live video stream from a camera or recorder. Our checks send only an RTSP OPTIONS request, which opens no stream. See Device health.

Alarm monitoring

Alarm receiving centre (ARC): A control room that receives alarm signals from its clients' sites and acts on them. Also called a monitoring centre or central station. See For alarm receiving centres.
Back-to-base monitoring: An alarm system that reports its events to an ARC, which responds for the client, rather than only sounding at the site. See For alarm receiving centres.
Monitoring software: The program the control room's operators work in. It files each alarm signal on the client's account and shows it on screen. We can send alarm signals into it. See Alarm signals into your monitoring software.
SIA DC-09: An open standard from the Security Industry Association for sending alarm events over the internet to a monitoring centre's receiver, which acknowledges each message. See SIA DC-09 explained.
Contact ID: A numeric alarm event format: a digit for a new event or a restore, a three-digit event code and a zone. Inside SIA DC-09 it is marked ADM-CID. We can send our alarm signals in Contact ID or SIA format. See Alarm signals into your monitoring software.

Building and IT devices

BACnet: The protocol building controllers use for heating, ventilation and other building services. Our checks read a controller's status over BACnet/IP, read-only. See For facilities and building services.
Modbus: A protocol that inverters, batteries and EV chargers answer. Our checks read their status over Modbus TCP, read-only. See For solar and energy installers.
SNMP: Simple Network Management Protocol: how printers, UPSes, switches and NAS report how they are. Our checks read it, in versions 1, 2c and 3, read-only. See For IT providers.

Relayant's own terms

Relayant box: A small box that plugs into a LAN port of the site's router and connects out to Relayant over an encrypted WireGuard tunnel. Nothing is opened or forwarded on the router. See The Relayant box.
Software agent: The box's own software, installed on hardware the site already has: a Linux service on a PC or Raspberry Pi, or a router package. It works the same way as a box. See Software agent.
Cloud relay: Our service that carries the connection between your control room and the site. Each device you choose gets one address and port on it. See Remote access.
Local relay: A PC in your control room that the site boxes dial directly. It offers the devices as local ports, so camera traffic stays on your own network. See Setting up local relays.
Allowed addresses: The internet addresses you list in the portal. Only they can reach a device's address on the relay. See Remote access.

Something in this guide is wrong or missing? Tell us: hello@relayant.net.