What Is Wireshark, How It Works & Example

Wireshark is one of the most popular network protocol analyzers used to capture, inspect, and troubleshoot network traffic. It helps network administrators, cybersecurity professionals, developers, and students understand what is happening on a network.

In simple words, Wireshark lets you see and analyze network packets traveling between devices.

For example, if a computer cannot access a website, Wireshark can help you determine whether the problem is related to DNS, TCP, TLS, HTTP, or another part of the network connection.

Important: Only capture and analyze network traffic that you own or are authorized to inspect. Captured traffic can contain sensitive information.

What Is Wireshark?

Wireshark is a free and open source network protocol analyzer. It captures network packets from a selected network interface and displays detailed information about those packets.

A packet is a small unit of data transmitted across a network.

When you open a website, send an email, stream a video, or use an online application, your device exchanges thousands of packets with other systems.

Wireshark can help you examine these packets and understand how the communication works.

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Simple Example

Suppose you open:

https://example.com

Your computer may perform several network operations:

1. Resolve the domain name using DNS.
2. Establish a connection with the destination server.
3. Establish TLS encryption for HTTPS.
4. Exchange application data.
5. Receive the server’s response.

Wireshark can show the network packets associated with these operations.

How Does Wireshark Work?

Wireshark works by capturing packets from a network interface such as:

• Wi-Fi
• Ethernet
• Virtual network interfaces
• Loopback interfaces

The general process looks like this:

Device → Network Interface → Packet Capture → Wireshark → Packet Analysis

Wireshark then decodes the packets according to their protocols and presents the information in a human-readable format.

For example, a captured packet might contain information related to:

• Source IP address
• Destination IP address
• Protocol
• Source port
• Destination port
• Packet length
• TCP flags
• DNS information
• TLS information

The amount of information visible depends on the protocol and whether encryption is being used.

What Is a Network Packet or (wireshark online)?

Before learning wireshark online, it is important to understand packets.

A network communication is divided into smaller units called packets.

For example, when you request information from a web server, the communication is transferred through multiple packets.

A simplified packet can be represented as:

• Source Information
• Destination
• Protocol Information
• Data                

Wireshark allows you to inspect the different protocol layers contained in captured packets.

Main Features of Wireshark

Wireshark provides many features for network analysis.

1. Live Packet Capture

Wireshark can capture packets as they travel through a supported network interface.

This is useful for troubleshooting problems while they are happening.

2. Protocol Analysis

Wireshark can decode and display many different network protocols.

Common examples include:

• TCP
• UDP
• DNS
• DHCP
• ARP
• ICMP
• HTTP
• TLS
• IPv4
• IPv6

3. Packet wireshark Filter

Large packet captures can contain thousands or millions of packets.

Wireshark provides display filters that allow you to focus on specific traffic.

For example:

dns

displays DNS related packets.

To view TCP traffic:

tcp

To view traffic associated with a particular IP address:

ip.addr == 192.168.1.10

These filters make packet analysis much easier.

4. Packet Details

Selecting a packet allows you to expand its protocol layers and inspect fields in detail.

For example, a TCP packet may show:

• Source port
• Destination port
• Sequence number
• Acknowledgment number
• TCP flags
• Window size

5. Statistics

Wireshark provides various statistics that can help identify network behavior.

Examples include:

• Protocol hierarchy
• Conversations
• Endpoints
• Packet lengths
• I/O graphs

Understanding the Wireshark Interface

After starting Wireshark, you will typically see a list of available network interfaces.

Examples might include:

Wi-Fi

Ethernet

Loopback

Select the interface that is carrying the traffic you want to analyze.

The main packet list area commonly contains columns such as:

For example:

This provides a high level view of network communication.

Wireshark and Common Network Protocols

Understanding common protocols makes Wireshark much easier to use.

DNS

DNS (Domain Name System) translates domain names into IP addresses.

For example:

example.com

      ↓

93.184.216.34

You can use this filter:

dns

to focus on DNS packets.

TCP

TCP (Transmission Control Protocol) provides reliable communication between systems.

A TCP connection commonly begins with the three way handshake:

Client → SYN → Server

Client ← SYN-ACK ← Server

Client → ACK → Server

This is called the TCP three way handshake.

UDP

UDP (User Datagram Protocol) provides connectionless communication and is commonly used where low overhead and speed are important.

Examples include DNS queries and some real time applications.

ICMP

ICMP (Internet Control Message Protocol) is commonly used for network diagnostic and control messages.

The ping command is a familiar example.

A Wireshark filter for ICMP traffic is:

icmp

Example: Troubleshooting or (wireshark network analyzer) a Website That Will Not Open

For wireshark network analyzer Imagine an employee reports:

“I can access Google, but one particular website is not opening.”

Instead of guessing, a network administrator can use Wireshark to investigate the problem.

Step 1: Start Wireshark

The administrator opens Wireshark and selects the computer’s active network interface.

For example:

Wi-Fi

Step 2: Start Capturing

The administrator starts the packet capture and then attempts to open the problematic website in a browser.

Suppose the user visits:

https://example.com

Step 3: Check DNS

The administrator first looks at DNS traffic.

A display filter can be used:

dns

The administrator may see:

DNS Query

example.com

DNS Response

example.com → 93.184.216.34

This suggests that DNS resolution is working.

Step 4: Check TCP

Next, the administrator examines TCP traffic.

A filter such as:

tcp

can be used.

The administrator looks for the TCP handshake:

Client → Server: SYN

Server → Client: SYN-ACK

Client → Server: ACK

If the handshake completes, the client can establish the TCP connection.

Step 5: Check TLS

Because the website uses HTTPS, the next stage involves TLS.

The administrator may see TLS related packets indicating that the client and server are negotiating an encrypted connection.

However, the contents of properly encrypted HTTPS application traffic are generally not readable simply by capturing packets.

Step 6: Identify the Problem

Suppose the capture shows repeated connection attempts:

Client → Server: SYN

Client → Server: SYN

Client → Server: SYN

but no corresponding:

Server → Client: SYN-ACK

The administrator now has evidence that the connection is not completing.

This could point to a problem such as:

• Network routing
• Firewall filtering
• Server availability
• Incorrect network configuration
• Connectivity between the client and destination

The administrator can then investigate the relevant network component.

Why This Is Useful

Without packet analysis, someone might simply say:

“The website is down.”

Wireshark provides much more information.

It can help determine where the communication is failing, rather than relying only on assumptions.

Another Example: Slow Network Performance

Imagine an office where employees complain:

“The internet is very slow today.”

A network administrator captures traffic and analyzes it with Wireshark.

The administrator may investigate:

1. DNS response times
2. TCP retransmissions
3. TCP connection behavior
4. Packet loss
5. Network conversations
6. Traffic volume
7. Protocol distribution

For example, if many TCP retransmissions appear, this may indicate a network quality problem that deserves further investigation.

A useful display filter can be:

tcp.analysis.retransmission

This helps focus on packets Wireshark has identified as TCP retransmissions.

Useful wireshark sample captures and Wireshark Display Filters

Here are some wireshark sample captures filters:

Show DNS traffic

dns

Show TCP traffic

tcp

Show UDP traffic

udp

Show ICMP traffic

icmp

Show traffic from an IP

ip.src == 192.168.1.10

Show traffic to an IP

ip.dst == 192.168.1.10

Show traffic involving an IP

ip.addr == 192.168.1.10

Show TCP retransmissions

tcp.analysis.retransmission

Show HTTP traffic

http

Keep in mind that modern websites predominantly use HTTPS, so ordinary application content from HTTPS connections is encrypted.

Wireshark Tool vs Other Network Tools

Wireshark is powerful, but it is different from command line tools such as Nmap and tcpdump.

These tools can also complement one another during network troubleshooting and security work.

What Can Wireshark Be Used For?

Wireshark has many legitimate uses.

Network Troubleshooting

Administrators can investigate:

• Connection failures
• Packet loss
• Retransmissions
• DNS problems
• Protocol errors
• Performance issues

Cybersecurity

Security professionals can use packet captures to investigate suspicious network activity and understand communication patterns.

Learning Networking

Students can use Wireshark to see concepts such as:

• TCP handshakes
• DNS queries
• ARP
• DHCP
• ICMP
• IP communication

instead of learning these concepts only from diagrams.

Application Troubleshooting

Developers can use packet captures to investigate communication problems between applications and servers.

Is Wireshark Safe to Use?

Yes. Wireshark itself is a legitimate network analysis tool.

However, the traffic you capture may contain sensitive information, depending on the network and protocols involved.

For example, captures may contain:

• IP addresses
• DNS requests
• Device information
• Metadata
• Unencrypted application data

Therefore, use Wireshark only on networks and systems you are authorized to monitor.

Do not capture other people’s network traffic without permission.

Wireshark and HTTPS Encryption

One important point for beginners is that Wireshark does not magically decrypt HTTPS traffic.

Suppose you visit:

https://example.com

Wireshark can still show network level information such as:

• Source and destination IP addresses
• TCP connections
• Packet sizes
• Timing
• TLS handshake information

But the actual encrypted application content is normally protected by TLS.

This is one reason why understanding network metadata versus encrypted payload data is important in cybersecurity.

Benefits of Learning Wireshark

Learning Wireshark can significantly improve your understanding of networking and cybersecurity.

Benefits include:

• Better network troubleshooting skills
• Understanding real network protocols
• Learning how TCP/IP works
• Investigating connectivity problems
• Analyzing packet behavior
• Developing cybersecurity skills
• Understanding network attacks in authorized lab environments

Beginner how to use wireshark

If you are new to Wireshark, learn it in this order:

Step 1: Learn Networking Fundamentals

Understand:

• IP addresses
• MAC addresses
• Ports
• TCP
• UDP
• DNS
• DHCP
• ARP
• ICMP

Step 2: Install Wireshark

Install Wireshark on your operating system and identify your active network interface.

Step 3: Capture Your Own Traffic

Start with safe experiments on your own computer.

For example:

• Open a website
• Run ping
• Perform a DNS lookup
• Start a download

Then observe the resulting packets.

Step 4: Learn Display Filters

Start with:

dns

tcp

udp

icmp

Then progress to more specific filters.

Step 5: Study TCP

Learn how the TCP three way handshake works and identify:

SYN

SYN, ACK

ACK

Step 6: Analyze Problems

Practice identifying:

• Retransmissions
• Failed connections
• DNS failures
• Connection delays

Use intentionally created lab traffic or traffic from systems you are authorized to monitor.

Conclusion

Wireshark is an essential tool for learning and analyzing computer networks. It allows you to observe network packets and investigate how devices communicate.

A troubleshooting scenario demonstrates its value: when a website fails to open, Wireshark can help determine whether DNS resolution, TCP connection establishment, TLS negotiation, or another network component is involved.

For students and cybersecurity beginners, Wireshark is especially valuable because it turns abstract networking concepts into something you can see, inspect, and analyze.

Start by capturing traffic from your own computer, learn basic protocols such as DNS, TCP, UDP, ARP, and ICMP, and gradually move toward more advanced packet analysis techniques.