RezwanAhmed & His Team || Software Engineer


DHCP Dynamic Host Configuration Protocol

DHCP – Dynamic Host Configuration Protocol [RFC 2131]. DHCP allows a host to obtain (be allocated) an IP address automatically. A network administrator can configure DHCP so that a given host receives the same IP address each time it connects to the network, or a host may be assigned a temporary IP address that will be different each time the host connects to the network. In addition to host IP address assignment, DHCP also allows a host to learn additional information, such as its subnet mask, the address of its first-hop router (often called the default gateway), and the address of its local DNS server.

DHCP’s ability to automate the network-related aspects of connecting a host into a network, it is often referred to as a plug-and-play protocol. This capability makes it very attractive to the network administrator who would otherwise have to perform these tasks manually!

DHCP is also enjoying widespread use in residential Internet access networks and in wireless LANs, where hosts join and leave the network frequently. Consider, for example, the student who carries a laptop from a dormitory room to a library to a classroom. It is likely that in each location, the student will be connecting into a new subnet and hence will need a new IP address at each location. DHCP is ideally suited to this situation, as there are many users coming and going, and addresses are needed for only a limited amount of time.



The Internet is a computer network that interconnects hundreds of millions of computing devices throughout the world. We’ll use the public Internet, a specific computer network, as our principal vehicle for discussing computer networks and their protocols.

A Nuts-and-Bolts Description

Internet : Computing devices were primarily traditional desktop PCs, Linux workstations, and so-called servers that store and transmit information such as Web pages and e-mail messages. Increasingly, however, nontraditional Internet end systems such as laptop, Smartphone, tablets, TVs, gaming consoles, Web cams, automobiles, environmental sensing devices, picture frames, and home electrical and security systems are being connected to the Internet.

Indeed, the term computer network is beginning to sound a bit dated, given the many nontraditional devices that are being hooked up to the Internet. In Internet language, all of these devices are called hosts or end systems.



A ping test is a method of checking if the computer is connected to a network. It also determines the latency or delay between two computers. It is used to ensure that a host computer which your computer tries to access is operating. A ping test is a physical test to determine the natural frequency of an object or assembly.

5G : 5th Generation or 5G Technology Will Save Time

5th Generation or 5G Technology will deliver faster speeds and lower latency.
With 5G technology, movie downloads will decrease from 7 minutes to just 6 seconds. People will save 2 minutes and 20 seconds a day waiting for social media content to load, 7 minutes when downloading an HD movie, nearly 7 hours on large game downloads.

5G is like having high-powered Wi-Fi routers dispersed all over the city to function as the network nodes. So, your internet provider’s network will function more like your home network, but much faster.”

5G nodes can’t cover the same area as a cell tower but will transmit data at higher speeds. To make up for the reduced coverage area, companies will need to install more 5G nodes. 


Overview of the IPsec Protocol Suite

The IP security protocol, more commonly known as IPsec, provides security at the network layer. IPsec secures IP datagrams between any two network-layer entities, including hosts and routers. As we will soon describe, many institutions (corporations, government branches, non-profit organizations, and so on) use IPsec to create Virtual Private Networks (VPNs) that run over the public Internet. 

In the IPsec Protocol Suite, there are two principal protocols: the Authentication Header (AH) protocol and the Encapsulation Security Payload (ESP) protocol.

When a source IPsec entity (typically a host or a router) sends secure datagrams to a destination entity (also a host or a router), it does so with either the AH protocol or the ESP protocol.

The AH protocol provides source authentication and data integrity but does not provide confidentiality. The ESP protocol provides source authentication, data integrity, and confidentiality.

Because confidentiality is often critical for VPN and other IPsec applications, the ESP protocol is much more widely used than the AH protocol. In order to de-mystify IPsec and avoid much of its complication, we will henceforth focus exclusively on the ESP protocol. Readers wanting to learn also about the AH protocol are encouraged to explore the RFCs and other online resources.

IP Sec Protocol Sructure Diagram


VPN – Virtual Private Network


VPN, Virtual Private Network – the institution’s interoffice traffic is sent over the public Internet rather than over a physically independent network. But to provide confidentiality, the inter-office traffic is encrypted before it enters the public Internet.

When a user connects to a VPN, a “tunnel” is created. This tunnel acts as a secure line of communication. The information passed through it can’t be read if intercepted because it has been encrypted. The VPN client on your computer and the VPN Server know the key to the encryption so data is only encrypted in transit, but instantly decipherable at the source and destination.

There has some best VPN software people use, when facing trouble in Internet or block any application services. All of these solid VPN software are :
1. Betternet VPN,
2. Hotspot Shield
3. Opera
4. TunnelBear
5. PureVPN
6. CyberGhost VPN

History of TLS and SSL

Transport Layer Security (TLS)
A slightly modified version of Secure Sockets Layer SSL version 3, called Transport Layer Security (TLS), has been standardized by the IETF (Internet Engineering Task Force ) [RFC 2246]. TLS uses HMAC for MAC, additional alert codes, different digest functions and different set of encryption algorithm.

A simplified version of SSL, one that will allow us to get a big-picture understanding of the why and how of SSL. We will refer to this simplified version of SSL as “almost-SSL.”

Almost-SSL (and SSL) has three phases: handshake, key derivation, and data transfer.

TLS Transport Layer Security

Transport Layer Security (TLS)

A slightly modified version of Secure Sockets Layer SSL version 3, called Transport Layer Security (TLS), has been standardized by the IETF (Internet Engineering Task Force ) [RFC 2246]. TLS uses HMAC for MAC, additional alert codes, different digest functions and different set of encryption algorithm.

The SSL protocol was originally designed by Netscape, but the basic ideas behind securing TCP had predated Netscape’s work (for example, see Woo [Woo 1994]). Since its inception, SSL has enjoyed broad deployment. SSL is supported by all popular Web browsers and Web servers, and it is used by essentially all Internet commerce sites (including Amazon, eBay, Yahoo!, MSN, and so on).

Tens of billions of dollars are spent over SSL every year.

In fact, if you have ever purchased anything over the Internet with your credit card, the communication between your browser and the server for this purchase almost certainly went over SSL. (You can identify that SSL is being used by your browser when the URL begins with https: rather than http.)

SSL addresses these issues by enhancing TCP with confidentiality, data integrity, server authentication, and client authentication. SSL is often used to provide security to transactions that take place over HTTP. However, because SSL secures TCP, it can be employed by any application that runs over TCP.