Port sniffer - Open Port

Port sniffer

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The software which analyses and carries out this procedure is called a port sniffer. In this article, we will explain to you the concept of port sniffing. How it is used to analyze the data flow and some efficient administrator based port sniffers available in the market.

Port sniffer

Port sniffer | Image by Pete Linforth from Pixabay

One’s internet activity goes through various routers, open ports, and switches until it reaches its destination. However, this activity, which is transmitted in the form of data packets, is highly sensitive to be analyzed (sniffed) by third-party sources which can then provide details about the total data flow and the loss of data during transmission. This procedure is known as packet sniffing.

A brief introduction to port sniffers

Amongst a wide variety of network types, the most commonly used form of networking is TCP/IP (Transmission Control Protocol over Internet Protocol). In layman’s terms, it merely means that the network uses TCP-type data packets to the destination terminal using discrete IP addresses. Contrary to popular notion, data to the destination terminal is not sent as a whole. It is broken down into several pieces called packets, which are then transmitted through routers and ports before it is assembled again and sent to the destination. During transmission, however, these data packets are sensitive to a loss if there are any loopholes in the ports. To analyze this loss, we use specialized software called a port sniffer.

What is a packet sniffing?

Before getting to know how packet sniffing works, we need to understand how routing in internet networking functions. Web pages, emails, and messages are not sent through the internet as a whole format. They are broken up into several pieces, called packets- before it reaches its destination. The source machine is responsible for breaking data into packets. In a TCP/IP mechanism, these packets are assigned to a specific IP address at the receiving terminal.

It is nothing but typical that the receiving end has to receive all the packets. That is why all the packets have the source and destination IP address assigned to it along with some other information to ensure that the source receives the packets correctly.

The procedure of transmission of data packets from the source to the destination does not take place in one elaborative step. Each packet has to go through various ports and traffic control switches before it reaches its destination. It might adversely affect the data packets and might result in loss. To monitor this loss, an analysis is done, which checks the source and destination IPs before it passes through that traffic control port. It is called packet sniffing. The software used for packet sniffing is called a port sniffer.

Packet sniffing is also done by those who have access to the ports through which data packets pass through. Hence, your data is susceptible to eavesdropping by third-party members- the likes of which include your network provider, the government itself or some dark web vendors.

There are six types of packet sniffing. These are as follows:

  • TCP Sniffing: Uses the mechanism of a TCP-based three-way handshake.
  • SYN Sniffing: Sniffs by generating nascent IP packages to analyze responses from ports.
  • UDP Sniffing: Sniffs whether a port is open or closed with the help of an ICMP-based message
  • ACK Sniffing: Sniffs whether the port is filtered or unfiltered
  • Window Sniffing: Outdated sniffing mode
  • FIN Sniffing: Can bypass firewalls unlike SYN Sniffers

The utility of port sniffers

If you are looking to get a detailed view of your network traffic and bring about a certain amount of control over data flow and data loss. One can use dedicated software that carries out packet sniffing. This software is known as a port sniffer.

A port sniffer is a dedicated application that has been designed to examine a server or a host for leaking ports. This application is used by both administrators and attackers alike. The former uses this application to verify that there is no loophole in the network web, while the attackers use it to gain information about IPs.

Best port sniffers available in the market:

Here we have provided a list of best port sniffers and network analyzers:

  1. SolarWinds Deep Packet Inspection and analysis tool: Gives a detailed analysis of what causes network slowdown. Uses in-depth root inspections to enable you to resolve any issues which are not visible on the surface. One can filter these traffic ports through application, category and leakage risk-levels to eliminate the problems that might be there in the network. It is the best administrator-based port sniffer available.
  2. Paessler Packet Capture Tool: This tool combines a port sniffer, a NetFlow sensor, an SFlow sensor and a J-Flow Sensor built together into one.
  3. ManageEngine NetFlow Analyser: This traffic analysis tool works with a combination of Flow Inspection mechanisms like NetFlow, JFlow, sFlow, IPFIX, and AppFlow.
  4. Omnipeek Network Protocol Analyser: This is a network analyzer that can also work as a packet capturer at the same time to determine the efficiency of network ports.
  5. TCPdump: TCPdump is free software that captures packets. It is one of the most commonly used port sniffers and is considered essential for every network manager.
  6. Windump: Another free packet capture and network analysis tool.
  7. TShark: TShark brings out the best of both worlds: the flurry of functionality that WireShark provides, and the minimalistic profile that TCPdump offers.
  8. Network Miner: Network Miner is a Windows-based network monitoring software which comes with a minimalistic and no-frills functionality in its free version.
  9. Fiddler: A packet capturing software whose main focus is HTTP-based traffic.

Other port sniffers available right now include Capsa, NMap, IPVoid and DNSChecker

Conclusion

Packet sniffing is still a debatable procedure as it can be used for unsavory purposes as well. To gain access to user’s data. Governments and dark-web vendors have been accused of using this procedure for eavesdropping purposes. However, it is an essential tool for administrators to analyze and filter out networks. I hope you liked this article on the concept of port sniffer and how to use it as an administrator.

 


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