Traditionally IP (Internet Protocol) addresses were given to identify computers or Laptops installed on a Local area network (LAN) or the Internet. The IP address was originally fixed (static) for each PC. As computer networks became bigger and allocating a separate address to each computer became cumbersome, non permanent addressing was introduced. This is where the address was allocated by a central server and changed depending on the amount of Computers on the network and when they were turned on or off. This type of address is known as a dynamic address and is more convenient.
Cellular Fixed IP address
However a device with a fixed ip address can be accessed from anywhere on the Internet once the address is known. As the Internet of Things (IoT) and M2M Communications become more popular having hardware with a fixed ip address means it can be polled for information at regular internals. For example data from a weather station that is connected to a cellular gateway with a fixed ip address and web browser can be viewed online once the gateway is connected to the mobile network and the internet.
This is done by creating an access point on the network for GPRS/3G/4G connectivity.
The access point is given a name known as an APN (Access Point Name)Every network provider has a public APN. When the SIM card is enabled for data e.g. GPRS/3G etc the public APN is added by default. The IP address of the SIM card can be fixed or dynamic.
Public Versus Private APN.
All networks have a Public APN. It is visible to the public.This makes it less secure. A Private APN gives a customer direct access to their LAN and allows them to specify certain parameters such as the private address space allocated to the device. With a private network traffic is private and data never goes on to the public network. It stays on the GPRS/3G/4G network. As it is not visible it is not prone to virus attacks or unauthorised access.
Public IP address?
A public IP address is visible to the public at all times. Other people can access a device with a public ip address
Private IP address
The internet standards group has retained some ip addresses that are private and not visible to the public.These addresses are listed below
Private IP addresses are typically used on local networks including business, school and home. Devices with private IP addresses cannot connect directly to the Internet. Likewise, computers outside the local network cannot connect directly to a device with a private IP. Instead, access to such devices must be brokered by a router or similar device that supports Network Address Translation (NAT). NAT hides the private IP numbers but can selectively transfer messages to these devices, affording a layer of security to the local network.
With a fixed Public IP address, you can connect to your device from any machine anywhere. You do not need to set up a VPN tunnel. This is an ideal solution for customers who do not have a firewall or do not require to set up a VPN tunnel of some type. However as it is a public IP address, the device is open for anyone to connect to if they know the IP address.
With a Private IP address the IP address for the device is not known to the outside world. As a result the device cannot be accessed from any machine anywhere unless there is a secure VPN tunnel set up between the device and the machine.
This is suitable for those who do not want others to see their data.