Wireshark, a network analysis tool formerly known as Ethereal, captures packets in real time and display them in human-readable format. Wireshark includes filters, color coding, and other features that let you dig deep into network traffic and inspect individual packets.
This tutorial will get you up to speed with the basics of capturing packets, filtering them, and inspecting them. You can use Wireshark to inspect a suspicious programs network traffic, analyze the traffic flow on your network, or troubleshoot network problems.
Getting Wireshark
You can download Wireshark for Windows or macOS from its official website. If youre using Linux or another UNIX-like system, youll probably find Wireshark in its package repositories. For example, if youre using Ubuntu, youll find Wireshark in the Ubuntu Software Center.
Just a quick warning: Many organizations dont allow Wireshark and similar tools on their networks. Dont use this tool at work unless you have permission.
Capturing Packets
After downloading and installing Wireshark, you can launch it and double-click the name of a network interface under Capture to start capturing packets on that interface. For example, if you want to capture traffic on your wireless network, click your wireless interface. You can configure advanced features by clicking Capture > Options, but this isnt necessary for now.
As soon as you click the interfaces name, youll see the packets start to appear in real time. Wireshark captures each packet sent to or from your system.
If you have promiscuous mode enabledits enabled by defaultyoull also see all the other packets on the network instead of only packets addressed to your network adapter. To check if promiscuous mode is enabled, click Capture > Options and verify the Enable promiscuous mode on all interfaces checkbox is activated at the bottom of this window.
Click the red Stop button near the top left corner of the window when you want to stop capturing traffic.
Color Coding
Youll probably see packets highlighted in a variety of different colors. Wireshark uses colors to help you identify the types of traffic at a glance. By default, light purple is TCP traffic, light blue is UDP traffic, and black identifies packets with errorsfor example, they could have been delivered out of order.
To view exactly what the color codes mean, click View > Coloring Rules. You can also customize and modify the coloring rules from here, if you like.
Sample Captures
If theres nothing interesting on your own network to inspect, Wiresharks wiki has you covered. The wiki contains a page of sample capture files that you can load and inspect. Click File > Open in Wireshark and browse for your downloaded file to open one.
You can also save your own captures in Wireshark and open them later. Click File > Save to save your captured packets.
Filtering Packets
If youre trying to inspect something specific, such as the traffic a program sends when phoning home, it helps to close down all other applications using the network so you can narrow down the traffic. Still, youll likely have a large amount of packets to sift through. Thats where Wiresharks filters come in.
The most basic way to apply a filter is by typing it into the filter box at the top of the window and clicking Apply (or pressing Enter). For example, type dns and youll see only DNS packets. When you start typing, Wireshark will help you autocomplete your filter.
You can also click Analyze > Display Filters to choose a filter from among the default filters included in Wireshark. From here, you can add your own custom filters and save them to easily access them in the future.
For more information on Wiresharks display filtering language, read the Building display filter expressions page in the official Wireshark A pplication.
Another interesting thing you can do is right-click a packet and select Follow > TCP Stream.
Youll see the full TCP conversation between the client and the server. You can also click other protocols in the Follow menu to see the full conversations for other protocols, if applicable.
Close the window and youll find a filter has been applied automatically. Wireshark is showing you the packets that make up the conversation.
Inspecting Packets
Click a packet to select it and you can dig down to view its details.
You can also create filters from here just right-click one of the details and use the Apply as Filter submenu to create a filter based on it.
Wireshark is an extremely powerful tool, and this tutorial is just scratching the surface of what you can do with it. Professionals use it to debug network protocol implementations, examine security problems and inspect network protocol internals.
You can find more detailed information in the official Wireshark Users Guide and the other Ap plication pages on Wiresharks website.
Download Page: https://www.wireshark.org/download.html
Source : https://www.howtogeek.com/104278/how-to-use-wireshark-to-capture-filter-and-inspect-packets/
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