TCP IP Networking Basics

by Amir Sadeghian Posted on | Information Security

Basically, computers are connected to each other through networks, we can divide the networks into two main categories of :

  • LAN (Local Area Networks): LAN networks used for connecting computers in limited areas such as an office, a building or schools.
  • WAN (Wide Area Networks): WAN networks connect LAN networks to each other. The most obvious example of these networks is the Internet.

Networks other than having benefits of ease in connectivity and sharing data, they also have some security risks as well. These security risks derive from the fact, which you open a pathway from your computer to the outside world. Therefore security professionals have to have a good understanding of networks and network protocols used to protect Confidentiality, Integrity, Availability of information in computer networks. 

TCP/IP protocols suite

TCP/IP is the most common standard for networking. TCP/IP protocols suite consist of four main protocols such as:

  • Internet Protocol (IP): IP protocol is responsible for delivering packets from the source computer to the destination computer based on the IP addresses in the packets headers. IP also breaks the data to smaller packages known as “Packet” for sending them over the network. The whole Internet network relay on the IP addresses. IP has two versions. Version 4 which established in 1981 and still is in use but later because engineers felt there will be more demand for address spaces they introduce IP version 6 in 1998. But still, IP V6 is not very adopted and it is due to the fact that IP V4 and IP V6 are not compatible.
  • Transmission Control Protocol (TCP): TCP protocol is responsible for providing a reliable and guaranteed packet delivery between computers. TCP protocol uses a “three-way handshake process” for establishing the connection between the computers. In this process, the client sends a “Synchronized packet (SYN)” to the server which wants to connect to. Afterward, the server will receive this package and in response sends a “Synchronized/Acknowledge packet (SYN/ACK)”. ACK packet is showing that the server received the packet successfully and the SYN packet is for establishing a connection to the client-side. In the last step when the client received the SYN will send an ACK packet to the server to finalize and establish the connection.
  • User Datagram Protocol (UDP): UDP also likes the TCP used for sending Datagrams (messages), the only difference is that this method is not reliable because there is no handshake exist for making the connection. Mostly UDP used in cases that guarantied delivery is not necessary.
  • Internet Control Message Protocol (ICMP): ICMP protocol used by computers and systems in the networks to manage and control the fellow of data on the network. When there is a traffic problem in the network ICMP messages used to inform computers or routers. They also used when the destination unreachable.

In the end, if you are interested to know your public IP address you just need to search the word “IP” in the Google search engine. You can also refer to the IP2Location website which can show more information based on your IP address. On this website, you can check the country, city and the ISP name of any IP address.