Wireshark is the world’s leading network traffic analyzer, and an essential tool for any security professional or systems administrator. This free software lets you analyze network traffic in real time, and is often the best tool for troubleshooting issues on your network.
Common problems that Wireshark can help troubleshoot include dropped packets, latency issues, and malicious activity on your network. It lets you put your network traffic under a microscope, and provides tools to filter and drill down into that traffic, zooming in on the root cause of the problem. Administrators use it to identify faulty network appliances that are dropping packets, latency issues caused by machines routing traffic halfway around the world, and data exfiltration or even hacking attempts against your organization.
Does it really bite?
Wireshark is a powerful tool that requires sound knowledge of networking basics. For most modern enterprises, that means understanding the TCP/IP stack, how to read and interpret packet headers, and how routing, port forwarding, and DHCP work, for example.
What does Wireshark do?
Wireshark intercepts traffic and converts that binary traffic into human-readable format. This makes it easy to identify what traffic is crossing your network, how much of it, how frequently, how much latency there is between certain hops, and so forth.
While Wireshark supports more than two thousand network protocols, many of them esoteric, uncommon, or old, the modern security professional will find analyzing IP packets to be of most immediate usefulness. The majority of the packets on your network are likely to be TCP, UDP, and ICMP.
Given the large volume of traffic that crosses a typical business network, Wireshark’s tools to help you filter that traffic are what make it especially useful. Capture filters will collect only the types of traffic you’re interested in, and display filters will help you zoom in on the traffic you want to inspect. The network protocol analyzer provides search tools, including regular expressions and colored highlighting, to make it easy to find what you’re looking for.
Sometimes the best way to find anomalous traffic is to capture everything and establish a baseline.