Internet Protocol addresses (IP addresses)
It is our device's address on 'www'(World Wide Web) or internet.Each devices (smartphone,laptop etc) connected to the internet has assigned it's own IP address.

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Dynamic Host Configuration Protocol (DHCP)

• It assigns IP addresses dynamically (different IP address everytime) to the network devices but the subnet and range remains same.
  For instance, 192.168.0.0 - 192.168.255.255.

• When each device is connected to a network, it request an IP address. That device sends that request to the DHCP server which then assigns an IP address to that device for a fixed length of time known as a "lease".

Behind the scenes

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Network Address Translation (NAT)

With this protocol internal private IP addresse is "translated" to an external public IP address that can be routed through the internet to its destination.

NAT device first accepts requests from an internal machine to travel the internet. It then records that machine's IP address in a table and converts the IP address to the external IP address of the router.

Static network address translation (static NAT) is a type of NAT technique that routes and maps network traffic from a static public IP address to an internal private IP address and/or network.

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Static IP - fixed or dedicated IP addresses

• It is manually configured for a device and not assigned by DHCP. It's called static because it doesn't change (opposite of dynamic).
• It makes contacting or finding someone easy on the internet and is useful for hosting a website,remote access,port forwarding.DNS servers use static IP addresses so that devices always knows how to connect to them.
• The major disadvantage that static IP addresses have over dynamic addresses is that the devices must be configured manually.
• By default networks uses DHCP provided IPs and the public IP address assigned to the routers of home and business network is a dynamic IP address.

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Ports
IP address is the primary address and the port is the sub-address.

IP Address - Street Address

Port - Apartment Number

• The IP address gets us to right machine, but the port takes us to correct service, say HTTP on port 80.There are 65536 (2¹⁶ ports).
• The first 1,024 are generally referred to as the "common ports".

• Every software in computer is usually programmed to send its packets through a specific port.

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Port forwarding
Port forwarding is the redirecting of computer signals to follow specific electronic paths (ports) into the computer. It increases speed dramatically.

How packets are transfered?

Packets follow stop-and-go set of rules, where they are required to stop at each major network network intersection and do three things:

1. Find an open port.

2. Pass the identification test that will allow them through that port, and if not...

3. Move to the next port and try again, until they are allowed to pass through one.

In some cases, packets sent by hackers will be caught and held at the intersection, where they will then be dissolved into random electrons.

Instead of having every packet stop at each port in turn until it finds an open port, a router can be programmed to speed up the process by identifying and redirecting packets through port forwarding.

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