Trending February 2024 # Avast Keeps Detecting My Network As A New One # Suggested March 2024 # Top 7 Popular

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Avast Keeps Detecting My Network as a New One [Fix] Tested solutions for Avast detecting network as new issue

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Avast detecting an old network as a new one can be due to outdated Avast software on your PC.

Updating the Avast client on your PC can fix the problem in no time.

Avast and some other antiviruses are fond of causing network connection issues. Many users complain about a problem where Avast says a new network is detected while connecting to a recent one.

Also, users complain about getting a stable antivirus for router protection on their devices.

Why does Avast keep detecting my network as new?

Avast detecting a recent network as a new one can occur for many reasons that vary from issues with the antivirus software and your PC. The most common reason is outdated Avast antivirus software on your PC. It can cause the app to malfunction and result in issues.

Furthermore, Avast can affect your network connection due to other factors, such as:

Avast firewall interference – The network issue can occur due to the interference of the Avast firewall, prompting you to reconnect to an old network as a new one. Also, the firewall can override previous connections for some reason. Check how to allow programs through the firewall here.

Issues with the network – The router network you’re connected to may be faulty or corrupt, so Avast can override the previous connection and show it as a new one. So, a compromised driver can cause it.

Virus and malware – Avast can say a new network is detected when you have an old network because of virus and malware activities on your device. It can affect your device’s performance and prompt some issues with Avast.

The cause of the problem may differ for various users. Nevertheless, you can fix the problem by following the troubleshooting steps below.

What can I do if Avast keeps detecting my network as new?

Here are some important preliminary checks:

Power cycle your network router and reconnect to the network.

Restart Windows in Safe Mode and check if the problem persists.

Try the following solutions if the problem persists:

1. Turn off the Avast shield on your PC

Expert tip:

This should fix most Avast antivirus issues on your PC.

3. Troubleshoot Network Adapter

Troubleshooting the network adapter will detect any issues with the network components on your PC that can cause the error.

Network routers can be infected by bugs from outdated firmware, resulting in errors that cause them to malfunction. So, updates and patches are deployed to fix these issues on your router.

The updating steps differ for every router device. However, you can navigate the router menu and check for the router Firmware update option. Also, you can contact the manufacturer for guidance on how to update your router.

5. Uninstall the Avast antivirus with Utility

NOTE

This is the last option to consider, as it can affect your security settings and permanently delete the configurations you have on Avast.

The uninstall tool will uninstall the Avast app and clear its data which can still prompt the problem on your PC.

Alternatively, take a closer look at our in-depth comparison of Windows Defender and Avast to know which is the most preferred. You can also check how to fix Avast blocking iTunes on Windows 11.

Still experiencing issues?

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What Is My Network Security Key? – Complete Guide

In today’s busy schedules we need to rely upon the security keys for protecting the devices from any unwanted access.

Your network security key or Wi-Fi password allows you to gain access to the wiles network.

It establishes a connection between the wireless/network device and the user who is requesting for getting access.

But sometimes your computer may be asking for that specific key and you get throttled with what is my network security key!

We have shown a VIDEO walk through at the end of the post for easy solution.

Now let us study what are the common types of network security keys.

Wi-Fi Protected Access or WPA/WPA2 and Wired Equivalent Privacy or WEP are the most common ones.

When we are using some weak keys, the cyber criminals can easily get access to our stored data giving you serious troubles. 

The WEP key is recommended for the devices using Wi-Fi. These keys act in a smarter way letting devices share encrypted messages in the meantime and denying access to decode or read them by any outsider.

They consist of numbers from 0-9 and alphabets from A to F and is generated automatically.

Depending upon the Web version, the length of a WEP key may consist of 10 or 26 or even 58 characters.

But one can easily crack these codes endangering the stored data and information.

These are much stronger than the WEP keys. You can easily obtain the WPA password from the net-owner. It is printed on the side of the Wi-Fi router you are using.

These are used mainly by businessmen to ensure more security measures.

Now let us see how to find the security key. Have a look!

Check the side of the router you are using. It will have a sticker consisting of the Wireless Network’s Name, or SSID, along with the Wireless Security Key Password.

This password is your network security key. As I have stated above it has a combination of numbers and alphabets.

In case you are having a Wi-Fi connection to your computer, and you fail to remember the password, then you can access it by opening the settings of the Computer.

Follow the steps mentioned below in case your Computer is already connected to a Wi-Fi network.

For Windows

In case you are using Windows 10, then here is a detailed guide to find out your security key from the settings. Follow the given steps:

Step 1: First of all, press Win+R to open the Run command box and then enter chúng tôi in the box.

Step 2: When you hit the OK button, you will be led to the Network Connections options.

Step 3:  Make sure that you are connected to your Wi-Fi network.

Step 5: Now move on to the Security tab as I have shown below.

Now, this is going you reveal to you the network security key Windows 10.

Use Command Prompt To Find Your Wi-Fi Password

Follow the below mentioned steps to find the Wi-Fi password with the help of Command Prompt.

Step 1: First of all, go to the Start option and then type CMD in the box and open an elevated Command Prompt.

Step 2: Next enter the following command and hit the Enter button:

netsh wlan show profile

Step 3: Now a list of the WLAN profiles will get displayed and you may choose the network name accordingly.

Step 4: Next enter the below mention command that will reveal the password for a specific Wi-Fi connection.

netsh wlan show profile “Name of the Wi-Fi” key=clear

Now this is going to successfully reveal the network security key for a specific Wi-Fi connection.

For your Mac follow the procedure mentioned below if you are confused with how do I find my network security key.

Step 3:  Now choose the Show Password option and here enter the Mac password for revealing the network security key.

The hackers or cyber-criminals can easily access the password if you are having a weak password.

In case you have selected the WPA or WPA2 key, then make sure it is stronger.

You should establish the limit of how much you should write down the password.

You must change the passwords and security keys after every six months for your safety measures.

Also, make sure that you are not creating anything easy to find, such as the name of the family members or their birthdays. Create something complicated instead.

The firewalls you use, act as a virtual wall, and restricts to allow the intruders. The antivirus software scans the files for any malware or virus attack.

You must use antivirus software on your computer whenever you get a new system for protecting against some internal threats.

Both antivirus software and firewalls protect your network and always remember to update them at the first chance you get.

There are always the latest versions available ad updating them will ensure you some sort of protection from the attacks.

The cyber-criminals are always ready to hack your information if there is any security gap.

They are always ready to hack your personal information. There are also auto-updates available.

You can easily set for an auto-update when you are not using your PC, maybe in the late hours of the night. This will ensure you automatic protection even if you forget to do the task manually.

So, there you are! Hope the article has helped you to seek an answer to your what is my network security key.

If you have any more ideas or suggestions related to this topic, please feel free to use the dedicated section below.

You can also shoot us a mail if you have any further queries. We always look forward to hearing from you.

Google My Business Adds 4 New Attributes

Google is rolling out four new attributes that businesses can use to make their Google My Business listing stand out in search results.

Carrie Hill, a local search analyst with Sterling Sky, Inc., reports the following four attributes have started appearing in business’s knowledge panels:

Online Care

Online Appointment

Online Estimates

Online Classes

Businesses can add these, and any other existing attributes, to their GMB profile and Google may show them in search results for relevant queries.

Here’s an example of what the new “Online Care” attribute looks like in search result.

— Tom Waddington (@tomwaddington8) June 15, 2023

Attributes in a Google My Business profile are designed to grab searchers’ attention by highlighting important service offerings.

Searchers can use attributes to make more informed decisions about where to visit.

Attributes have traditionally been tailored toward people visiting the location in person, such as “WiFi,” “outdoor seating,” and things of that nature.

With many businesses still being forced to remain closed, there’s been a shift toward offering online services. In some cases, businesses are serving clients online for the first time ever.

Similarly, people are seeking online alternatives to services they can no longer access in person. This may include doctors, fitness instructors, therapists, and others.

Given the sudden change in services businesses are offering, and the change in services people are looking for, it’s time for Google My Business to be updated accordingly.

Related: How to Completely Optimize Your Google My Business Listing

How to Add Attributes to Your Google My Business Listing

Businesses can the new attributes, or existing attributes, to their Google My Business listing by following the steps below:

Sign in to Google My Business.

Open the location you’d like to manage.

You can search for the attribute you want to add, or scroll through all the available options for your business.

Note that all businesses do not have access to all attributes. Available attributes vary according to the category of business.

For example, a pizza delivery place is unlikely to be able to add attributes such as “online care” and “online classes” to their GMB listing.

If your business is one that would have any of the four new attributes as service offerings, then it’s likely you’ll have access to them in GMB.

Google has been rolling out a steady stream of updates to its GMB platform ever since the pandemic hit. This is the second time new attributes have been added in less than a month.

Back in May, Google My Business added three new attributes to help restaurants highlight whether they’re offering dine-in, takeout, or delivery services.

As businesses start to re-open now, I predict the next wave of attributes will be related to businesses’ safety measures.

In the future, businesses may be able to highlight whether masks are mandatory optional, for example.

It may become important for businesses to highlight their maximum capacity as well. Then, searchers can use the in-store traffic estimates to gauge whether it’s a good time time to visit.

That’s just me brainstorming–though I imagine it won’t be long before we see more GMB updates as businesses adjust to the “new normal.”

Source: Local University

Related: How to Get More from Your Google My Business Listing

A Teamwork Tool As Versatile As Your Workforce

Web conferencing technologies — from HD cameras to intuitive software — have enabled companies and organizations to stay connected and productive, even when getting together in person has been hard or impossible. Seeing familiar faces and sharing work remotely on computer screens has bridged divides, but the next big leap forward is display technology. Display technology enables rich, fluid collaboration between people, whether they’re in the same room or all over the world.

Interactive whiteboards have grown increasingly common in environments as varied as corporate meeting rooms and kindergarten classrooms. A new class of interactive, hypercollaborative Samsung displays embraces the spirit and foundational aspects of those digital whiteboards and gives them superpowers that make learning, sharing and collaboration easy and impactful, whether everyone is gathered as a group, or working and learning separately from home offices and kitchen tables.

And that’s where the latest in interactive technology will prove effective: Samsung’s Interactive Display comes in as a wall-mounted or stand-based, 85-inch, OPS-backed, multi-touch all-in-one dynamo that can suit the needs of anyone from the boardroom to the classroom and their at-home counterparts.

Bigger and even better

The latest in collaboration tools — Samsung’s Interactive Display — is changing team capabilities, packing a monster punch with its size: a wall-mounted 85-inch 4K resolution display that takes on the same kind of big visual canvas dimensions of classroom chalkboards and meeting space dry-erase boards. Here are the other highlights:

A wide selection of connectivity options are standard, including USB, HDMI, DisplayPort, near-field communication (NFC) and an Open Pluggable Slot (OPS) in the display that allows a compatible PC to be loaded.

Viewing and changes can be synchronized between the Samsung Interactive Display and a laptop. For example, a meeting leader can connect a personal device to the 85-inch display using the “touch out” function — controlling the content on the big display from a keyboard. In brainstorming sessions, edits made to the content on the large screen also change on the laptop display, and vice versa.

Forms and templates make the Interactive Display useful throughout a working day — running messaging, schedules and other need-to-know information, even when not in active use.

Easy sharing tools allow meeting leaders and educators to quickly capture and distribute the meeting output, whether brainstorming notes, marked-up drawings and other visuals, or new material shared by participants or found online, using the built-in browser.

Pen and brush modes allow as many as 20 simultaneous users for drawing, note taking or producing original, high-definition content.

Making wherever work

With an inexorable shift to remote working and learning accelerated by global health concerns in 2023, tools that go beyond voice and video calls, emails and attachments are more important than ever. It can be particularly important for executives who find themselves working from home, detached from their teams but still needing to visually communicate ideas and plans. For example, a chief technology officer (CTO) working virtually from the comfort of their home office can use a Samsung Interactive Display to mark up the plans for a major IT overhaul, while those same visuals show up on a sister device (the Flip 2 or another Samsung Interactive Display) running on the network at the main office, where a few colleagues have gathered at a limited capacity.

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Similar scenarios could play out across many industries and working and learning environments. Consider what might happen in education, healthcare and in the creative industry:

Teaching

Classrooms become more engaging and active when students can get up and use a large screen that everyone can see. As many as 20 people can use a Samsung Interactive Display simultaneously — whether they’re working out math equations, drawing pictures, making lists or marking up and editing images pulled from the internet.

The 85-inch Samsung Interactive Display has a built-in document viewer, allowing participants to access, show, discuss and work with files commonly used on computers and other personal devices. Built-in image editing tools let users easily select, move, crop, capture and edit images. Activity is built and archived around the idea of rolls, with as many as 20 pages or screens worth of writing or activity saved to a roll. Students working remotely can get the full recaps, including the visuals and annotations, effortlessly sent their way by email.

Caregiving Creating

Conventional paper flip charts and marker-based whiteboards limit the creative collaboration process to note taking and simple drawings. The Samsung Interactive Display’s high-precision multimedia capabilities enable creative teams to do everything from mark up proofs from graphic designers to create original designs — using stylus pen and brush tools. Creatives can draw bold oil paint strokes with a pen or create delicate watercolor scenes with a highly sensitive brush.

Chalkboards and whiteboards have been central to learning, sharing and innovating for decades. The new 85-inch Samsung Interactive Display takes that idea and optimizes it for today’s working and learning climate.

Learn more about the enhanced educational experiences digital signage can provide with this white paper. Then learn how you can enhance security on your Flip 2 by password protecting its content.

Bbc Iplayer Detecting/Blocking Vpn

BBC iPlayer detecting/blocking VPN [How to fix]

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BBC Iplayer is quite aggressive when it comes to blocking VPN users.

That’s not an uncommon practice among major players in the streaming services market.

Don’t give up on hope just yet – we have compiled a few tested solutions for you.

One of the most popular solutions is upgrading to a better VPN.

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INSTALL BY CLICKING THE DOWNLOAD FILE

To fix Windows PC system issues, you will need a dedicated tool

Fortect is a tool that does not simply cleans up your PC, but has a repository with several millions of Windows System files stored in their initial version. When your PC encounters a problem, Fortect will fix it for you, by replacing bad files with fresh versions. To fix your current PC issue, here are the steps you need to take:

Download Fortect and install it on your PC.

Start the tool’s scanning process to look for corrupt files that are the source of your problem

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VPNs are commonly used for security reasons as they provide the kind of privacy most people seek while online, through encrypted tunnels across the open internet architecture.

For people who travel a lot, and for long periods of time, VPNs come in handy both to keep data secure, while being able to access geo-restricted content whenever they want to watch their favorite shows on streaming media such as Netflix, Hulu, BBC iPlayer, or Amazon Prime, among others.

The primary reason for using a VPN, however, is to bypass internet censorship, as well as country level filtering, where there are serious censorship regulations. VPNs do this by hiding your current location and IP address such that the website you visit only sees that of your VPN, and not your real one.

If you’re a BBC fan and you’d like to access the content from a different location other than the UK, sometimes you’ll find your VPN blocked by BBC, and there are reasons why this happens.

Among these reasons is that BBC blocks VPN connections from accessing the iPlayer application, though it is hard to completely block out VPN access, which can involve manual intervention because a strong, well-configured VPN can go undetected.

In fact, some reports have said that about 60 million people outside the UK are able to access BBC’s iPlayer via VPN connections or other unblocking tools, which is a bigger population compared to those living in the UK.

This is probably why the BBC is actively stopping unauthorized users from accessing the content.

To resolve the VPN blocked by BBC issue, try the solutions below.

Has BBC blocked VPN? Here’s how to unblock it

1. Preliminary checks

Sometimes the VPN blocked by BBC issue happens because your VPN account may have expired so you’re unable to connect. Confirm if your account is still valid, or has expired.

Check third-party app settings like your security software settings which sometimes block the PPTP and L2TP protocols, especially when you set them higher than the normal level. Disable them and try connecting again, then, allow PPTP, L2TP, and IPSec through your antivirus and firewall and reenable the security software.

Check your router settings if you’re connected to a WiFi router.

Check for pass-through options for PPTP, L2TP, and IPSec, under Router Firewall/Security tab and enable them. If these options don’t exist, disable the router firewall and try again then reenable the firewall.

Check that you entered the correct user credentials – username and password for logins.

If you get an error message saying: You seem to be using an unblocker or proxy or You’ll need to disable your anonymizer, contact your VPN tech support team for help.

Check your IP address for information such as your city or region (country) next to the location you selected. If it shows a location near you, it means you’re not connected to a server location associated with your VPN, so try connecting again.

Check your internet connection by first disconnecting from your VPN and trying to access websites normally. If you cannot access even when disconnected from the VPN, check your internet connection.

Try connecting to a different UK VPN server.

Try switching the web browser you’re using.

Contact your VPN’s support team and see if they can help you bypass the VPN block.

2. Change your VPN

For guaranteed access, go for a VPN that is optimized for streaming such as Private Internet Access.

When it comes to fighting online censorship, PIA is unmatched. What’s more, this world-leading VPN provider has made it its mission, according to its own statement, to liberate the internet for you, as it was always intended.

With unlimited bandwidth and the highest download speeds, PIA is your best bet to unblock BBC content and enjoy all your favorite shows buffering-free and without worrying about ISP throttling.

In addition, all the servers composing PIA‘s impressive network of worldwide gateways are streaming and P2P sharing compatible, which takes out the question of having to blindly search for a server location that is not blocked by the BBC.

Simply activate your VPN, choose the server closest to you to rule out proximity-related issues, and enjoy a smooth, reliable, and stable connection for as long as you want.

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3. Download the latest version of your VPN

Uninstall the VPN app you’re running, sign in to your VPN account, and set up the VPN. Find the latest version for your device and reconnect, then see if you can access BBC.

To set up the VPN in Windows 10, do the following:

Find your VPN from the list and select Uninstall

Connect again to your VPN and see if you can access BBC

4. Get a dedicated IP address

This may cost you a little bit more, but if you want uninterrupted streaming, go for one. A dedicated IP address is harder to blacklist because the shared ones are already on BBC’s radar.

But with a dedicated IP, you won’t be sharing with many other people, just a few selected users, which makes you look like a regular household, compared to a big company.

5. Download the latest version of your VPN

Uninstall the VPN you’re running, then sign in to your VPN account and run the setup again. Find the latest version for your device and reconnect.

6. Flush the DNS

Flushing your DNS cache allows your computer to automatically access your VPN’s DNS for the proper/correct entries. To do this:

Select All Apps

Type ipconfig /flushdns and press Enter. A confirmation that says: Windows IP Configuration Successfully flushed the DNS Resolver Cache will be displayed

7. Manually configure DNS settings

Configure your computer with your VPN’s DNS servers’ IP addresses so that it automatically connects to your VPN’s DNS servers. Manually configuring your computer with other DNS server addresses helps you access BBC, and enjoy faster connection speeds. To do this:

In the Network connections window, find your usual connection, either LAN or Wireless network connection.

Select Use the following DNS server addresses

Type these Google DNS server addresses: Preferred DNS server 8.8.8.8; Alternate DNS server 8.8.4.4

If Google DNS is blocked, try the following: Neustar DNS Advantage (156.154.70.1 and 156.154.71.1) enter and press OK; Level3 DNS (4.2.2.1 and 4.2.2.2) enter and press OK

Once configured, flush old DNS entries again as described in the previous solution.

Slow VPN connection on Windows 10? Here’s how to speed it up.

8. Manually configure proxy settings

A proxy server hides your real location so you can access websites such as BBC. Ensure your browser is set to auto-detect proxy or no proxy, then use the instructions to manually configure proxy settings for your browser. To do this:

Select Internet Options

Go to the Connections tab

Your connection is not secure – websites you visit can find out your details:

Use a VPN to protect your privacy and secure your connection.

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A Primer On Network Communication

A Primer on Network Communication

We have always heard that to perform penetration testing, a pentester must be aware about basic networking concepts like IP addresses, classful subnetting, classless subnetting, ports and broadcasting networks. The very first reason is that the activities like which hosts are live in the approved scope and what services, ports and features they have open and responsive will determine what kind of activities an assessor is going to perform in penetration testing. The environment keeps changing and systems are often reallocated. Hence, it is quite possible that old vulnerabilities may crop up again and without the good knowledge of scanning a network, it may happen that the initial scans have to be redone. In our subsequent sections, we will discuss the basics of network communication.

Reference Model

Reference Model offers a means of standardization, which is acceptable worldwide since people using the computer network are located over a wide physical range and their network devices might have heterogeneous architecture. In order to provide communication among heterogeneous devices, we need a standardized model, i.e., a reference model, which would provide us with a way these devices can communicate.

We have two reference models such as the OSI model and the TCP/IP reference model. However, the OSI model is a hypothetical one but the TCP/IP is an practical model.

OSI Model

The Open System Interface was designed by the International organization of Standardization (ISO) and therefore, it is also referred to as the ISO-OSI Model.

The OSI model consists of seven layers as shown in the following diagram. Each layer has a specific function, however each layer provides services to the layer above.

Physical Layer

The Physical layer is responsible for the following activities −

Activating, maintaining and deactivating the physical connection.

Defining voltages and data rates needed for transmission.

Converting digital bits into electrical signal.

Deciding whether the connection is simplex, half-duplex or full-duplex.

Data Link Layer

The data link layer performs the following functions −

Performs synchronization and error control for the information that is to be transmitted over the physical link.

Enables error detection, and adds error detection bits to the data that is to be transmitted.

Network Layer

The network layer performs the following functions −

To route the signals through various channels to the other end.

To act as the network controller by deciding which route data should take.

To divide the outgoing messages into packets and to assemble incoming packets into messages for higher levels.

Transport Layer

The Transport layer performs the following functions −

It decides if the data transmission should take place on parallel paths or single path.

It performs multiplexing, splitting on the data.

It breaks the data groups into smaller units so that they are handled more efficiently by the network layer.

The Transport Layer guarantees transmission of data from one end to other end.

Session Layer

The Session layer performs the following functions −

Manages the messages and synchronizes conversations between two different applications.

It controls logging on and off, user identification, billing and session management.

Presentation Layer

The Presentation layer performs the following functions −

This layer ensures that the information is delivered in such a form that the receiving system will understand and use it.

Application Layer

The Application layer performs the following functions −

It provides different services such as manipulation of information in several ways, retransferring the files of information, distributing the results, etc.

The functions such as LOGIN or password checking are also performed by the application layer.

TCP/IP Model

The Transmission Control Protocol and Internet Protocol (TCP/IP) model is a practical model and is used in the Internet.

The TCP/IP model combines the two layers (Physical and Data link layer) into one layer – Host-to-Network layer. The following diagram shows the various layers of TCP/IP model −

Application Layer

This layer is same as that of the OSI model and performs the following functions −

It provides different services such as manipulation of information in several ways, retransferring the files of information, distributing the results, etc.

The application layer also performs the functions such as LOGIN or password checking.

Following are the different protocols used in the Application layer −

TELNET

FTP

SMTP

DN

HTTP

NNTP

Transport Layer

It does the same functions as that of the transport layer in the OSI model. Consider the following important points related to the transport layer −

It uses TCP and UDP protocol for end to end transmission.

TCP is a reliable and connection oriented protocol.

TCP also handles flow control.

The UDP is not reliable and a connection less protocol does not perform flow control.

TCP/IP and UDP protocols are employed in this layer.

Internet Layer

The function of this layer is to allow the host to insert packets into network and then make them travel independently to the destination. However, the order of receiving the packet can be different from the sequence they were sent.

Internet Protocol (IP) is employed in Internet layer.

Host-to-Network Layer

This is the lowest layer in the TCP/IP model. The host has to connect to network using some protocol, so that it can send IP packets over it. This protocol varies from host to host and network to network.

The different protocols used in this layer are −

ARPANET

SATNET

LAN

Packet radio

Useful Architecture

Following are some useful architectures, which are used in network communication −

The Ethernet frame architecture

An engineer named Robert Metcalfe first invented Ethernet network, defined under IEEE standard 802.3, in 1973. It was first used to interconnect and send data between workstation and printer. More than 80% of the LANs use Ethernet standard for its speed, lower cost and ease of installation. On the other side, if we talk about frame then data travels from host to host in the way. A frame is constituted by various components like MAC address, IP header, start and end delimiter, etc.

The Ethernet frame starts with Preamble and SFD. The Ethernet header contains both Source and Destination MAC address, after which the payload of frame is present. The last field is CRC, which is used to detect the error. The basic Ethernet frame structure is defined in the IEEE 802.3 standard, which is explained as below −

The Ethernet (IEEE 802.3) frame format

The Ethernet packet transports an Ethernet frame as its payload. Following is a graphical representation of Ethernet frame along with the description of each field −

Field Name Preamble SFD(Start of frame delimiter) Destination MAC Source MAC Type Data CRC

Size(in bytes) 7 1 6 6 2 46-1500 4

Preamble

An Ethernet frame is preceded by a preamble, 7 bytes of size, which informs the receiving system that a frame is starting and allows sender as well as receiver to establish bit synchronization.

SFD (Start of frame delimiter)

This is a 1-byte field used to signify that the Destination MAC address field begins with the next byte. Sometimes the SFD field is considered to be the part of Preamble. That is why preamble is considered 8 bytes in many places.

Destination MAC − This is a 6-byte field wherein, we have the address of the receiving system.

Source MAC − This is a 6-byte field wherein, we have the address of the sending system.

Type − It defines the type of protocol inside the frame. For example, IPv4 or IPv6. Its size is 2 bytes.

Data − This is also called Payload and the actual data is inserted here. Its length must be between 46-1500 bytes. If the length is less than 46 bytes then padding 0’s is added to meet the minimum possible length, i.e., 46.

CRC (Cyclic Redundancy Check) − This is a 4-byte field containing 32-bit CRC, which allows detection of corrupted data.

Extended Ethernet Frame (Ethernet II frame) Format

Following is a graphical representation of the extended Ethernet frame using which we can get Payload larger than 1500 bytes −

Field Name Destination MAC Source MAC Type DSAP SSAP Ctrl Data CRC

Size(in bytes) 6 6 2 1 1 1 >46 4

The description of the fields, which are different from IEEE 802.3 Ethernet frame, is as follows −

DSAP (Destination Service Access Point)

DSAP is a 1-byte long field that represents the logical addresses of the network layer entity intended to receive the message.

SSAP (Source Service Access Point)

SSAP is a 1-byte long field that represents the logical address of the network layer entity that has created the message.

Ctrl

This is a 1-byte control field.

The IP Packet Architecture

Internet Protocol is one of the major protocols in the TCP/IP protocols suite. This protocol works at the network layer of the OSI model and at the Internet layer of the TCP/IP model. Thus, this protocol has the responsibility of identifying hosts based upon their logical addresses and to route data among them over the underlying network. IP provides a mechanism to uniquely identify hosts by an IP addressing scheme. IP uses best effort delivery, i.e., it does not guarantee that packets would be delivered to the destined host, but it will do its best to reach the destination.

In our subsequent sections, we will learn about the two different versions of IP.

IPv4

This is the Internet Protocol version 4, which uses 32-bit logical address. Following is the diagram of IPv4 header along with the description of fields −

Version

This is the version of the Internet Protocol used; for example, IPv4.

IHL

Internet Header Length; length of the entire IP header.

DSCP

Differentiated Services Code Point; this is the Type of Service.

ECN

Explicit Congestion Notification; it carries information about the congestion seen in the route.

Total Length

The length of the entire IP Packet (including IP header and IP Payload).

Identification

If the IP packet is fragmented during the transmission, all the fragments contain the same identification number.

Flags

As required by the network resources, if the IP Packet is too large to handle, these ‘flags’ tell if they can be fragmented or not. In this 3-bit flag, the MSB is always set to ‘0’.

Fragment Offset

This offset tells the exact position of the fragment in the original IP Packet.

Time to Live

To avoid looping in the network, every packet is sent with some TTL value set, which tells the network how many routers (hops) this packet can cross. At each hop, its value is decremented by one and when the value reaches zero, the packet is discarded.

Protocol

Tells the Network layer at the destination host, to which Protocol this packet belongs, i.e., the next level Protocol. For example, the protocol number of ICMP is 1, TCP is 6 and UDP is 17.

Header Checksum

This field is used to keep checksum value of entire header, which is then used to check if the packet is received error-free.

Source Address

32-bit address of the Sender (or source) of the packet.

Destination Address

32-bit address of the Receiver (or destination) of the packet.

Options

This is an optional field, which is used if the value of IHL is greater than 5. These options may contain values for options such as Security, Record Route, Time Stamp, etc.

IPv6

The Internet Protocol version 6 is the most recent communications protocol, which as its predecessor IPv4 works on the Network Layer (Layer-3). Along with its offering of an enormous amount of logical address space, this protocol has ample features , which address the shortcoming of IPv4. Following is the diagram of IPv4 header along with the description of fields −

Version (4-bits)

It represents the version of Internet Protocol — 0110.

Traffic Class (8-bits)

These 8 bits are divided into two parts. The most significant 6 bits are used for the Type of Service to let the Router Known what services should be provided to this packet. The least significant 2 bits are used for Explicit Congestion Notification (ECN).

Flow Label (20-bits)

This label is used to maintain the sequential flow of the packets belonging to a communication. The source labels the sequence to help the router identify that a particular packet belongs to a specific flow of information. This field helps avoid re-ordering of data packets. It is designed for streaming/real-time media.

Payload Length (16-bits)

This field is used to tell the routers how much information a particular packet contains in its payload. Payload is composed of Extension Headers and Upper Layer data. With 16 bits, up to 65535 bytes can be indicated; but if the Extension Headers contain Hop-by-Hop Extension Header, then the payload may exceed 65535 bytes and this field is set to 0.

Next Header (8-bits)

Either this field is used to indicate the type of Extension Header, or if the Extension Header is not present then it indicates the Upper Layer PDU. The values for the type of Upper Layer PDU are same as IPv4’s.

Hop Limit (8-bits)

This field is used to stop packet to loop in the network infinitely. This is same as TTL in IPv4. The value of Hop Limit field is decremented by 1 as it passes a link (router/hop). When the field reaches 0, the packet is discarded.

Source Address (128-bits)

This field indicates the address of originator of the packet.

Destination Address (128-bits)

This field provides the address of the intended recipient of the packet.

The TCP (Transmission Control Protocol) Header Architecture

As we know that TCP is a connection-oriented protocol, in which a session is established between two systems before starting communication. The connection would be closed once the communication has been completed. TCP uses a three-way handshake technique for establishing the connection socket between two systems. Three-way handshake means that three messages — SYN, SYN-ACK and ACK, are sent back and forth between two systems. The steps of working between two systems, initiating and target systems, are as follows −

Step 1 − Packet with SYN flag set

First of all the system that is trying to initiate a connection starts with a packet that has the SYN flag set.

Step 2 − Packet with SYN-ACK flag set

Now, in this step the target system returns a packet with SYN and ACK flag sets.

Step 3 − Packet with ACK flag set

At last, the initiating system will return a packet to the original target system with ACK flag set.

Following is the diagram of the TCP header along with the description of fields −

Source Port (16-bits)

It identifies the source port of the application process on the sending device.

Destination Port (16-bits)

It identifies the destination port of the application process on the receiving device.

Sequence Number (32-bits)

The sequence number of data bytes of a segment in a session.

Acknowledgement Number (32-bits)

When ACK flag is set, this number contains the next sequence number of the data byte expected and works as an acknowledgment of the previous data received.

Data Offset (4-bits)

This field implies both, the size of the TCP header (32-bit words) and the offset of data in the current packet in the whole TCP segment.

Reserved (3-bits)

Reserved for future use and set to zero by default.

Flags (1-bit each)

NS − Explicit Congestion Notification signaling process uses this Nonce Sum bit.

CWR − When a host receives packet with ECE bit set, it sets Congestion Windows Reduced to acknowledge that ECE received.

ECE − It has two meanings −

If SYN bit is clear to 0, then ECE means that the IP packet has its CE (congestion experience) bit set.

If SYN bit is set to 1, ECE means that the device is ECT capable.

URG − It indicates that Urgent Pointer field has significant data and should be processed.

ACK − It indicates that Acknowledgement field has significance. If ACK is cleared to 0, it indicates that packet does not contain any acknowledgment.

PSH − When set, it is a request to the receiving station to PUSH data (as soon as it comes) to the receiving application without buffering it.

RST − Reset flag has the following features −

It is used to refuse an incoming connection.

It is used to reject a segment.

It is used to restart a connection.

SYN − This flag is used to set up a connection between hosts.

FIN − This flag is used to release a connection and no more data is exchanged thereafter. Because packets with SYN and FIN flags have sequence numbers, they are processed in correct order.

Windows Size

This field is used for flow control between two stations and indicates the amount of buffer (in bytes) the receiver has allocated for a segment, i.e., how much data is the receiver expecting.

Checksum − This field contains the checksum of Header, Data and Pseudo Headers.

Urgent Pointer − It points to the urgent data byte if URG flag is set to 1.

Options − It facilitates additional options, which are not covered by the regular header. Option field is always described in 32-bit words. If this field contains data less than 32-bit, padding is used to cover the remaining bits to reach 32-bit boundary.

The UDP (User Datagram Protocol) header architecture

UDP is a simple connectionless protocol unlike TCP, a connection-oriented protocol. It involves minimum amount of communication mechanism. In UDP, the receiver does not generate an acknowledgment of packet received and in turn, the sender does not wait for any acknowledgment of the packet sent. This shortcoming makes this protocol unreliable as well as easier on processing. Following is the diagram of the UDP header along with the description of fields −

Source Port

This 16-bits information is used to identify the source port of the packet.

Destination Port

This 16-bits information is used to identify the application level service on the destination machine.

Length

The length field specifies the entire length of the UDP packet (including header). It is a 16-bits field and the minimum value is 8-byte, i.e., the size of the UDP header itself.

Checksum

This field stores the checksum value generated by the sender before sending. IPv4 has this field as optional so when checksum field does not contain any value, it is made 0 and all its bits are set to zero.

To study TCP in detail, please refer to this link — User Datagram Protocol

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