Extending Your Network

Port forwarding, firewalls, VPNs

Port Forwarding

a network configuration technique that allows external devices to access services on a private network by redirecting network traffic from a public IP address and port to a specific device and port on the private network.

Virtual Private Network (or VPN)

a technology that allows devices on separate networks to communicate securely by creating a dedicated path between each other over the Internet (known as a tunnel).

VPN Technologies

VPN Technology	Description
PPP	This technology is used by PPTP (explained below) to allow for authentication and provide encryption of data. VPNs work by using a private key and public certificate (similar to SSH). A private key & certificate must match for you to connect. This technology is not capable of leaving a network by itself (non-routable).
PPTP	The Point-to-Point Tunneling Protocol (PPTP) is the technology that allows the data from PPP to travel and leave a network.  PPTP is very easy to set up and is supported by most devices. It is, however, weakly encrypted in comparison to alternatives.
IPSec	Internet Protocol Security (IPsec) encrypts data using the existing Internet Protocol (IP) framework. IPSec is difficult to set up in comparison to alternatives; however, if successful, it boasts strong encryption and is also supported on many devices.

Layer 2 Switch

These switches will forward frames (remember these are no longer packets as the IP protocol has been stripped) onto the connected devices using their MAC address.

Layer 3 Switch

they can perform some of the responsibilities of a router. Namely, these switches will send frames to devices (as layer 2 does) and route packets to other devices using the IP protocol. 

VLAN (Virtual Local Area Network)

Allows specific devices within a network to be virtually split up. This split means they can all benefit from things such as an Internet connection but are treated separately.