ackets (either IPv4 or IPv6) which travel across the Internet, regardless of the type of traffic they carry (voice, video, or some other data). IPs as well as all other Internet technologies are being standardized by the IETF (www .ietf.org) in a form of RFCs (request for comments). Not all RFCs are Internet standards, some are informational only. Also, there are Internet technologies which are proprietary and not standardized (e.g. developed by certain vendors). Such proprietary technolo- gies are typically developed on the application layer (e.g. various OTT applications in the public Internet), although there are also proprietary versions of some networking protocols, such as proprietary TCP versions and proprietary routing protocols. 2.1.2 Main Internet Transport Layer Protocols: TCP and UDP Internet networking is based on network layer protocol (IP) and transport layer proto- cols (TCP, UDP). Networking protocols are implemented in the operating system (OS) of the hosts or network nodes and they are connected with the application using the abstraction called "socket," as an endpoint of a communication call/session in IP envi- ronments. What is a "socket"? It is an abstraction which connects the IP address of the network interface (used for access to the IP network), port numbers, and type of transport pro- tocol being used in the communication. From an application point of view, it hides from the application all Internet networking protocols below (e.g. TCP/IP, UDP/IP), which are built into the os of the host or the network node (e.g. router, gateway). The socket interface for the application is defined with an application programming interface (API), which is specific to the os of the given host or network node. Therefore there is required development of a given application for a given os (different API exists in Windows, Linux, Android, iOS, etc.). From the network point of view, the socket is the endpoint of a given Internet connec- tion. So, if a typical connection includes two end parties (e.g. two Inte