Network packet analysis using tools like Wireshark, tcpdump

 How do Packet Sniffers work?

Every network has various components like workstations and servers, which are called nodes in networking terminology. The data is transferred in the form of packets between these nodes.

Every packet has actual data and control information. This control information helps the packet to reach the destination for the source. This control information includes various details like IP addresses of sender and receiver, packet sequencing information, etc.

When the data packets are transmitted through the network, they pass through several nodes in the network. These packet’s control information will get checked by each network adapter and the connected device. It is checked for the node it is headed toward.

For the normal circumstances, the packet gets ignored if it is addressed for another node. Packet sniffing programs make some nodes to collect all or a defined sample of packets regardless of their destination address. Packet Sniffers analyze the network by using these packets.

Best for small to large businesses.

Wireshark is a network protocol analyzer. You will get to see what is happening on your network at a microscopic level with the help of this tool. It is a popular tool and is used in many commercial and non-profit enterprises, government agencies, and educational institutions as a de facto standard. It supports various platforms such as Windows, Mac, Linux, Solaris, FreeBSD, NetBSD, etc.

Features:

• Wireshark can perform a deep inspection of hundreds of protocols. It keeps adding new protocols.
• It can capture live or perform offline analysis.
• Files that are compressed with gzip can be captured by Wireshark and decompressed on the fly.
• It will allow you to export the output to XML, PostScript, CSV, or Plain Text.

Verdict: Wireshark has powerful display filters in the industry. It supports many protocols for decryption like IPsec, ISAKMP, etc. It can read the live data from Ethernet, IEEE 802.11, PPP/HDLC, ATM, etc.

Price: Wireshark is a free and open-source tool.

Website: Wireshark

TCPdump

Best for users with in-depth knowledge of the tool.

TCPdump is a packet analyzer. This data-network packet analyzer is a powerful command-line tool. It is a portable C/C++ library for network traffic capture. It supports most of the Unix-like OS such as Linux, Solaris, FreeBSD, NetBSD, Mac OS, etc.

You can make the use of short and simple commands to perform the functions like capturing only failed packets, saving the captured packets to file, etc.

Features:

• TCPdump can print the contents of network packets.
• Packets from a network interface card can be read.
• It can write packets to standard output or a file.

Verdict: TCPdump is distributed with a BSD license. There is no need to have a heavy-duty PC to function the tool smoothly. There is a learning curve for this tool and you should know to use this tool while using it.

Price: TCPdump is free to use.

Website: TCPdump