Network Packet Sniffing Tools — A Complete Guide

What are Network Packets?

Every network comprises numerous elements, including workstations, servers, networking devices, and more. All of these elements are referred to as nodes in the context of networking. A stable network connection makes sure that data is sent between these nodes consistently and at a reasonable speed based on the capacity of the network. Modern networks include a combination of physical and wireless connectivity. Although, these networks use the same basic concepts for transmission of data. Data is exchanged among different nodes in a network in the form of compact data chunks known as packets. Depending on the network protocol, these packets have different formats. Along with actual data, the packets include control information to facilitate the transport of packets from transmitter to the receiver. As packets intended to be sent to a particular node frequently transit through several nodes in a network and have the possibility to reach at the inaccurate node, the control information is necessary. To make sure that packets arrive at their intended location, the control information comprises the IP (Internet Protocol) addresses of the source and the destination, packet sequencing information (such as packet number), and more.

What are Network Packet Sniffers and Why do we Need Them?

There is no defined way to retrieve the packets lost during communication in protocols like Transmission Control Protocol/Internet Protocol (TCP/IP). Network designers employ these protocols only in fault-tolerant networks, where communication is unaffected by losses that fall below predetermined limits. In contrast, in protocols like User Datagram Protocol (UDP), the sender keeps sending the packet until it gets the recipient’s acknowledgement. While improving transmission performance, it also uses more resources. It can cause considerable delays in net transmission rates if left unchecked. Packet sniffers provide a solution to resolve such issues.

Types of Network Packet Sniffers

1. Hardware Packet Sniffers: It is a hardware element that is inserted into a network in order to do packet sniffing. Network administrators frequently employ hardware packet sniffers to examine a specific area of a vast network. These packet sniffers are employed by the network managers to assure that all packets are collected without any loss due to routing, filtering, or any other network concern. The hardware packet sniffers may be configured to transmit all packets it has collected to a central location for additional analysis.

Advantages of Network Packet Sniffers

There are legitimate uses of packet sniffers, including monitoring employee network usage and safeguarding users against harmful files, conversations, and activities. A packet sniffer has several advantages such as improving network traffic, improving bandwidth efficiency, and many more, some of which are discussed below.

Use Case — Wireshark

  • The ‘Source’ and ‘Destination’ columns include source and destination identifying data. This data might be in the form of an IP address, a Media Access Control (MAC) address, or any other identification-based information. For example, in 39th packet, 192.168.2.1 and 192.168.2.130 represents the IP address of the source and destination respectively. Similarly, in 38th packet, a2:85:2a:14:5f:d2 represents the MAC address of the source and ‘Broadcast’ in the destination column represents that the message is being broadcasted to the network devices by the source.
  • The ‘Protocol’ column contains information about the network protocol utilised for communication. For example, in 39th packet, Address Resolution Protocol (ARP) protocol is mentioned which is used to map an IP address to the MAC address of the device that has that IP address. In this case, Wireshark provides MAC address of the source device which is inquiring about the device in the network having a specific IP address. In 38th packet, Domain Name System (DNS) protocol is mentioned which is used to send a DNS query to a name server to resolve a domain. For example, when any website is searched in the web browser, it triggers a DNS request, which is sent by the computer to a DNS server in order to get the website’s IP address.
  • Wireshark also provides the packet length in bits in the ‘Length’ section and the details about the packet in the ‘Info’ section. For example, in 39th packet, 42 in the Length column represents that the packet size is 42 bits and ‘Who has 192.168.2.1?’ in the Info section represents that the source is enquiring about the device in the network whose IP address is 192.168.2.1.

Comparing Top Network Packet Sniffers

Conclusion

Packet sniffing tools, as well as some of the most popular packet sniffers used by network administrators all over the world, have been thoroughly discussed. As described in the case of Wireshark, packet sniffers give critical information about packets such as network protocols used for transmission, source and destination identification, packet length, and other data related to the packets that are transferred from one node to another in a network. Network Packet Sniffers may be installed on all major platforms and provide useful features such as network infrastructure monitoring, bandwidth monitoring, efficiency improvement, and security enhancement.

References

1. https://www.softwaretestinghelp.com/network-packet-sniffers/

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