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Making a Case for Network TAPs to Provide Digital Legal Evidence

November 5, 2019

federal network visibility

Sometimes we come across interesting requests from customers that are outside the normal security and monitoring applications within data centers or branch office locations. Recently, a law enforcement agency reached out to Garland Technology with a question as to whether our Network TAPs could assist them in obtaining sound digital evidence for a trial. This is a great example of lawful intercept, a scenario when a government law enforcement agency is granted legal means to obtain communications network data pursuant to lawful authority for the purpose of analysis or evidence. It’s a similar concept to the examples you see in movies or television shows where the FBI gets a warrant to tap the phone line of someone under a federal investigation, except in this instance, we’re tapping the network data. 

Making a Case for Network TAPs 

The Network TAP (test access point) transmits both the send and receive data streams simultaneously on separate dedicated channels, ensuring all data arrives at the monitoring device in real time - 100% of the time. Because TAPs ensure 100% of the data arrives at the monitoring tool, they are CALEA approved for lawful intercept cases over SPAN ports.

The SPAN port on a switch, also sometimes called a mirror port, will drop packets when ports are oversubscribed and can cause distortions in real time communications like VoIP and video chats. Since the data cannot be trusted 100% of the time, they are not a reliable option for lawful intercept cases. 

Download: TAP vs SPAN [Free whitepaper]

 

Garland Technology + SYNESIS for Lawful Interception

In this instance, the law enforcement agency had already determined that they wanted to use a SYNESIS network packet recorder to ensure high speed data capture of the live network data. A network recorder is a specialized hardware appliance that has filtering capabilities that can be programmed to look for all the data packets associated with a target’s IP address, and then records that information in a digital format. Network recorder tools must have the ability to capture and store extremely large amounts of data, with advanced ones storing amounts in the petabyte range.

The law enforcement agency was looking for a way to properly capture and store data according to warrant parameters, while delivering data directly from the source to the mediation device without any human intervention or packet loss. In lawful intercept cases it’s important to be sure that the traffic feeding the packet recorder adheres to specific regulations providing clear access to all data without any loss of information or impact on the network being monitored. 

That’s why the agency turned to Garland. We have a long standing relationship with Toyo and have worked with their SYNESIS tool many times. We were able to deliver an integration solution that combines Garland’s Network TAPs that deliver a 100% complete full-duplex copy of network traffic without packet loss, to the SYNESIS network packet recorder. SYNESIS is the only solution available in the market today that can record and collect 100G traffic without losing a single bit. Using TAPs instead of SPAN ports ensures that the packet recorder didn’t sacrifice high fidelity lossless packet capture performance, regardless of the network speed. 

Toyo Lawful Intercept

The integrated solution provided the law enforcement agency with two critical components, the TAPs and network recorder appliances, both of which are needed for successful lawful interception. If the solution were unable to access and record data completely at network speeds up to 100G, it would compromise the integrity of the surveyed data. And more importantly the incomplete data captures likely wouldn’t hold up in court. 

It isn’t every day we get to collaborate on such interesting cases. It’s solutions and applications like these that make my job fun. Now if I only knew what cases they were using our TAPs to help solve, that would be really interesting!

Looking to add a visibility solution to your next deployment, 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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