Category: Wireshark

Wireshark is a powerful tool for network support technicians who are trying to troubleshoot connectivity issues and optimize network performance. In this series, we have covered a number of features in Wireshark that can be particularly useful for troubleshooting network issues, including:

• “Follow TCP Stream”
• “Decode As”
• “IO Graphs”
• “Expert Infos”
• “Time Sequence Graph (tcptrace)”
• “Conversation Filter”
• “Graphical Time Sequence (grep)”
• “Statistics”

In the following summary, we will provide a brief overview of each of these features and how they can be used to troubleshoot network issues.

• “Follow TCP Stream” allows you to see all of the packets in a particular TCP stream in a single window, making it easier to understand the conversation between two devices.
• “Decode As” allows you to change the way that Wireshark decodes and displays a particular protocol, which can be useful when the default decoding is not correct or when you want to see more detailed information about the protocol.
• “IO Graphs” allows you to create graphs of packet and byte rates over time, which can help you identify trends and patterns in network traffic.
• “Expert Infos” displays alerts and warnings about potential problems with the packets being captured, such as retransmissions or out-of-order packets.
• “Time Sequence Graph (tcptrace)” displays a graph of TCP packet sequence numbers over time, which can help you identify problems with the TCP connection.
• “Conversation Filter” allows you to filter the packets being displayed based on their source and destination addresses, which can be useful when you are trying to focus on a specific conversation.
• “Graphical Time Sequence (grep)” displays a graph of packet transmission times over time, which can help you identify trends and patterns in network traffic.
• “Statistics” provides a wide range of statistical information about the packets being captured, including “Protocol Hierarchy,” “Endpoints,” “IO Graphs,” “Conversations,” “Flow Graph,” “TCP Stream Graphs,” and “HTTP.”
• “Protocol Hierarchy” displays a graphical representation of the protocols being used on your network, with the most frequently used protocols at the top. It is useful for identifying potential problems with your network.

Overall, Wireshark is a powerful tool that can be used to troubleshoot a wide range of network connectivity issues. By using the features discussed in this series, network support technicians can quickly and effectively identify and resolve problems with their networks, improving overall performance and reliability. Whether you are a seasoned network support professional or just starting out, learning how to use Wireshark is a valuable skill that can help you troubleshoot and optimize your network.

Using Wireshark to Troubleshoot Network Connectivity Issues: Statistics

In addition to the “Follow TCP Stream,” “Decode As,” “IO Graphs,” “Expert Infos,” “Time Sequence Graph (tcptrace),” “Conversation Filter,” and “Graphical Time Sequence (grep)” features, Wireshark also includes a tool called “Statistics” that provides a wide range of statistical information about the packets being captured.

To use the “Statistics” feature, simply select the “Statistics” menu and then choose the type of statistical information that you want to view. Wireshark provides a number of different options, including “Protocol Hierarchy,” “Endpoints,” “IO Graphs,” “Conversations,” “Flow Graph,” “TCP Stream Graphs,” and “HTTP.”

Part A: How to Use the Protocol Hierarchy
To use the “Protocol Hierarchy” option in the “Statistics” feature in Wireshark, follow these steps:

Select the “Statistics” menu and then choose “Protocol Hierarchy.”
In the “Protocol Hierarchy” window, you will see a graphical representation of the protocols being used on your network, with the most frequently used protocols at the top.
To view more detailed information about a specific protocol, click on the protocol in the graph. This will open a new window with a breakdown of the packets being captured for that protocol.

Part B: Why the Protocol Hierarchy is Useful
The “Protocol Hierarchy” option in the “Statistics” feature is useful for a number of reasons:

It provides a high-level overview of the protocols being used on your network. By seeing which protocols are being used the most, you can get a sense of the types of traffic that are generating the most activity on your network.

It helps you identify any potential problems with your network. For example, if you see that a particular protocol is being used much more frequently than others, it could be a sign that there is a problem with that protocol or that it is being used excessively.

It allows you to drill down into specific protocols to get more detailed information. By clicking on a specific protocol in the graph, you can open a new window with a breakdown of the packets being captured for that protocol, which can help you identify any issues with the packets or the protocol itself.

It helps you optimize your network by identifying any protocols that are using up too much bandwidth or causing other performance issues. By identifying and addressing these issues, you can improve the overall performance of your network.

Overall, the “Protocol Hierarchy” option in the “Statistics” feature in Wireshark is a valuable tool for network support technicians who are trying to troubleshoot connectivity issues and optimize network performance.

Using Wireshark to Troubleshoot Network Connectivity Issues: Graphical Time Sequence (grep)

In addition to the “Follow TCP Stream,” “Decode As,” “IO Graphs,” “Expert Infos,” “Time Sequence Graph (tcptrace),” and “Conversation Filter” features, Wireshark also includes a tool called the “Graphical Time Sequence (grep)” feature that allows you to visualize the flow of traffic between two devices over time in a graphical format.

To use the “Graphical Time Sequence (grep)” feature, simply select the “Statistics” menu and then choose “TCP Stream Graphs -> Time-Sequence Graph (Stevens).” This will open a new window that allows you to choose the stream that you want to visualize.

The “Graphical Time Sequence (grep)” feature shows the flow of traffic between two devices over time, with the x-axis representing time and the y-axis representing the sequence numbers of the packets being sent. You can use this tool to identify any problems with the flow of traffic, such as delays or missing packets.

By using the “Graphical Time Sequence (grep)” feature in combination with other diagnostic tools, such as the “Follow TCP Stream” and “IO Graphs” features, you can gain a deeper understanding of the traffic on your network and identify potential problems. With a little bit of practice and a thorough understanding of the features and techniques available in Wireshark, you can become an expert at troubleshooting network issues and keeping

Using Wireshark to Troubleshoot Network Connectivity Issues: Conversation Filter

In addition to the “Follow TCP Stream,” “Decode As,” “IO Graphs,” “Expert Infos,” and “Time Sequence Graph (tcptrace)” features, Wireshark also includes a tool called the “Conversation Filter” that allows you to view the packets being exchanged between two specific devices or between devices using a specific protocol.

To use the “Conversation Filter” feature, simply select the “Statistics” menu and then choose “Conversations.” This will open a new window that displays a list of all the conversations that have been captured.

You can use the “Conversation Filter” feature to view the packets being exchanged between two specific devices or between devices using a specific protocol. To filter the conversations, you can use a variety of criteria, including the source and destination addresses, the protocol being used, and various other packet attributes.

The “Conversation Filter” feature is especially useful when you want to focus on a specific set of packets and see how they are being exchanged between devices. By using the “Conversation Filter” feature in combination with other diagnostic tools, such as the “Follow TCP Stream” and “IO Graphs” features, you can gain a deeper understanding of the traffic on your network and identify potential problems.

How to Use the Conversation Filter
To use the “Conversation Filter” feature in Wireshark, follow these steps:

Select the “Statistics” menu and then choose “Conversations.”
In the “Filter” field at the top of the window, enter the criteria that you want to use to filter the conversations.
Click the “Apply” button to apply the filter and display the filtered conversations.
For example, if you want to see the packets being exchanged between two specific devices, you can enter the IP addresses of the devices in the “Filter” field. If you want to see the packets being exchanged between devices using a specific protocol, you can enter the name of the protocol in the “Filter” field.

With a little bit of practice and a thorough understanding of the features and techniques available in Wireshark, you can become an expert at troubleshooting network issues and keeping your network running smoothly

Using Wireshark to Troubleshoot Network Connectivity Issues: Time Sequence Graph (tcptrace)

In addition to the “Follow TCP Stream,” “Decode As,” “IO Graphs,” and “Expert Infos” features, Wireshark also includes a tool called the “Time Sequence Graph (tcptrace)” that allows you to visualize the flow of traffic between two devices over time.

To use the “Time Sequence Graph (tcptrace)” feature, simply select the “Statistics” menu and then choose “TCP Stream Graphs.” This will open a new window that allows you to choose the stream that you want to visualize.

The “Time Sequence Graph (tcptrace)” feature shows the flow of traffic between two devices over time, with the x-axis representing time and the y-axis representing the sequence numbers of the packets being sent. You can use this tool to identify any problems with the flow of traffic, such as delays or missing packets.

By using the “Time Sequence Graph (tcptrace)” feature in combination with other diagnostic tools, such as the “Follow TCP Stream” and “IO Graphs” features, you can gain a deeper understanding of the traffic on your network and identify potential problems. With a little bit of practice and a thorough understanding of the features and techniques available in Wireshark, you can become an expert at troubleshooting network issues and keeping your network running smoothly.

Using Wireshark to Troubleshoot Network Connectivity Issues: Expert Infos

In addition to the “Follow TCP Stream,” “Decode As,” and “IO Graphs” features, Wireshark also includes a tool called “Expert Infos” that provides valuable information and insights about the packets being captured.

To use the “Expert Infos” feature, simply select the “Statistics” menu and then choose “Expert Infos.” This will open a new window that displays a list of all the packets being captured, along with any expert infos that are available.

Expert infos are messages generated by Wireshark that provide additional information about the packets being captured. There are three levels of expert infos: “Notes,” “Warnings,” and “Errors.” Notes provide general information about the packets, warnings indicate potential problems with the packets, and errors indicate serious problems with the packets.

You can use the “Expert Infos” feature to identify any issues with the packets being captured, such as problems with the protocol being used or errors in the packet contents. By using the “Expert Infos” feature in combination with other diagnostic tools, such as the “Follow TCP Stream” and “IO Graphs” features, you can gain a deeper understanding of the traffic on your network and identify potential problems.

With a little bit of practice and a thorough understanding

Using Wireshark to Troubleshoot Network Connectivity Issues: IO Graphs

In addition to the “Follow TCP Stream” and “Decode As” features, Wireshark also includes a useful tool called “IO Graphs” that allows you to visualize the traffic on your network in a graphical format.

To use the “IO Graphs” feature, simply select the “Statistics” menu and then choose “IO Graphs.” This will open a new window that allows you to customize the graph according to your needs.

You can use the “IO Graphs” feature to identify patterns in the traffic and see how different devices are interacting with each other. For example, if you see a sudden spike in the traffic on your network, you can use the “IO Graphs” feature to identify which device or devices are causing the spike and determine the cause.

You can also use the “IO Graphs” feature to identify any problems with the traffic on your network, such as slow performance or connectivity issues. By visualizing the traffic in this way, you can often identify the root cause of the problem and take the appropriate action to fix it.

With a little bit of practice and a thorough understanding of the features and techniques available in Wireshark, you can become an expert at troubleshooting network issues and keeping your network running smoothly.

Using Wireshark to Troubleshoot Network Connectivity Issues: Decode As

Another useful feature in Wireshark is the “Decode As” feature, which allows you to specify how Wireshark should interpret the contents of a packet. This can be especially helpful when dealing with protocols that are not natively supported by Wireshark, or when you want to see the contents of a packet in a different format.

To use the “Decode As” feature, first select the packet in the packet list that you want to decode. Then, right-click on the packet and select “Decode As” from the context menu. This will open a dialog box that allows you to specify how Wireshark should interpret the contents of the packet.

In the “Decode As” dialog box, you can choose the protocol that you want Wireshark to use when decoding the packet. For example, if you are dealing with a packet that uses a custom protocol that is not natively supported by Wireshark, you can choose the “Custom” option and specify the details of the protocol.

You can also use the “Decode As” feature to specify how Wireshark should interpret the contents of a packet when it is using a protocol that is natively supported by Wireshark. For example, if you want to see the contents of an HTTP packet in a different format, such as ASCII or Hex Dump, you can use the “Decode As” feature to specify the desired format.

By using the “Decode As” feature in combination with other diagnostic tools, such as the “Follow TCP Stream” and “IO Graphs” features, you can gain a deeper understanding of the traffic on your network and identify potential problems. With a little bit of practice and a thorough understanding of the features and techniques available in Wireshark, you can become an expert at troubleshooting network issues and keeping your network running smoothly.

Using Wireshark to Troubleshoot Network Connectivity Issues: Filters

In addition to the “Follow TCP Stream” feature, Wireshark also includes a powerful set of filters that you can use to narrow down the packets being displayed and focus on specific issues.

To use filters in Wireshark, simply enter the filter criteria into the filter bar at the top of the packet list. You can use a wide range of criteria to filter the packets, including the source and destination addresses, the protocol being used, and various other packet attributes.

For example, if you want to see only packets that are being sent from a specific IP address, you can enter “ip.src == x.x.x.x” into the filter bar, where x.x.x.x is the IP address you want to filter for. You can also use logical operators, such as “and” and “or”, to create more complex filters.

Filters can be especially helpful when trying to identify the cause of connectivity issues, as they allow you to focus on specific packets or types of traffic that may be causing the problem.

Regenera