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The Network Analyzer: Sniffing Out The Sniffer

August 20, 2014

A network analyzer, otherwise known as a packet analyzer, protocol analyzer, or network sniffer, is an incredibly prominent tool in the business world. These hardware or software applications intercept, inspect, and collect data traffic for the analysis of network statistics and problems, detection of intrusion attempts, and more.

Network analyzers intercept and record the traffic passing over your network. As its information flows through, the analyzer captures each packet of data. Some businesses or IT teams also wish to decode the raw data of each packet, which a packet analyzer is capable of doing.

How Businesses Utilize Network Analyzers

Businesses leverage these applications in many different ways. Network analysis gives you the ability to:


Inform
Be informed about your network’s performance, statistics, problems, user activity (including sensitive information such as login details or user cookies), and more.

Monitor
Monitor your network’s usage (including internal and external users and systems), WAN bandwidth utilization, data-in-motion, and WAN and endpoint security status.

Capture
Packet capture – the process of intercepting and logging traffic – is sometimes used to fulfill a warrant from a law enforcement agency, although it’s most relevant to Internet and VoIP service providers.

Detect
Detect intrusion attempts on your network and any misuse by internal or external network users.

Debug
Debug your client/server communications and network protocol implementations.

Verify
Verify the effectiveness of your internal control systems and any adds, moves, and changes to your network.

 

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Bringing The Sniffer Up To Snuff


Keep in mind that while a network analyzer is capable of providing you with all of these capabilities, it is only as strong as its weakest link. This means that if a network design is flawed, there is no guarantee that your sniffer is giving you complete data.

For instance, an oversubscribed SPAN port may not provide 100 percent of your network’s traffic data, and if oversubscribed, it might not be available to allow an analyzer to do its job. A network TAP, on the other hand, provides foolproof access to your network and gives you the ability to monitor multiple network segments simultaneously.

Proper connection between your network and sniffer – or any network tools – is key to your ability to successfully monitor, capture, detect, debug, verify, and stay informed on your network. Without it, you can’t be certain that there isn’t anything falling through the cracks.

A network analyzer is a powerful, incredibly useful tool. But successful network analysis is an impossible task without complete access to a system’s network traffic. Full access is essential. With proper connectivity and complete access, a sniffer gives you important information and the power to manage your network.

Looking to add network TAP visibility to your packet analysis, but not sure where to start?  Join us for a brief network Design-IT consultation or demo. No obligation - it’s what we love to do.

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Heartbeats Packets Inside the Bypass TAP

If the inline security tool goes off-line, the TAP will bypass the tool and automatically keep the link flowing. The Bypass TAP does this by sending heartbeat packets to the inline security tool. As long as the inline security tool is on-line, the heartbeat packets will be returned to the TAP, and the link traffic will continue to flow through the inline security tool.

If the heartbeat packets are not returned to the TAP (indicating that the inline security tool has gone off-line), the TAP will automatically 'bypass' the inline security tool and keep the link traffic flowing. The TAP also removes the heartbeat packets before sending the network traffic back onto the critical link.

While the TAP is in bypass mode, it continues to send heartbeat packets out to the inline security tool so that once the tool is back on-line, it will begin returning the heartbeat packets back to the TAP indicating that the tool is ready to go back to work. The TAP will then direct the network traffic back through the inline security tool along with the heartbeat packets placing the tool back inline.

Some of you may have noticed a flaw in the logic behind this solution!  You say, “What if the TAP should fail because it is also in-line? Then the link will also fail!” The TAP would now be considered a point of failure. That is a good catch – but in our blog on Bypass vs. Failsafe, I explained that if a TAP were to fail or lose power, it must provide failsafe protection to the link it is attached to. So our network TAP will go into Failsafe mode keeping the link flowing.

Glossary

  1. Single point of failure: a risk to an IT network if one part of the system brings down a larger part of the entire system.

  2. Heartbeat packet: a soft detection technology that monitors the health of inline appliances. Read the heartbeat packet blog here.

  3. Critical link: the connection between two or more network devices or appliances that if the connection fails then the network is disrupted.

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