Hack the Connect. Breaking CAT 9’s Tricky Encryption


CAT9 Ethernet cable, officially referred to as Category 9 cable, is an Ethernet cable designed to support high-speed data transfer rates up to 10 Gigabits per second (Gbps) [https://wirefaren.com/cat9/]. CAT9 provides faster speeds and more bandwidth capacity compared to previous CAT cable versions like CAT5, CAT5e, and CAT6.

CAT9 cables are popular for use cases that require extremely fast and stable wired network connections, such as data centers, financial trading networks, scientific computing clusters, and backbone network links. The higher bandwidth enables reliable high-speed transfers of very large files and data sets.

Reasons to Break a CAT9

There are a few key reasons you may need to break and reconnect a CAT9 Ethernet cable:


If you are having network issues, breaking the CAT9 cable and reconnecting it can help identify if the cable is faulty. By cutting the cable and attaching new connectors, you can test each segment of the cable individually. This troubleshooting technique can isolate the problem to a bad connector or cable segment. According to experts on Reddit, sometimes it’s worth testing CAT cables by cutting and reconnecting to diagnose problems.

Cable is Too Long

CAT9 cables have a maximum recommended length of 100 meters. If your existing CAT9 cable is too long for your needs, you may need to cut it to shorten the cable. Breaking the CAT9 in the middle allows you to remove any excess cable and reconnect the two working ends.

Rerouting Cable

If you need to reroute your CAT9 Ethernet cable due to office layout changes or for better cable management, you may need to cut into the middle of the cable to redirect it. Breaking and reconnecting the CAT9 allows you to place the new connectors where you need them.

Security Reasons

In secure environments like data centers, Ethernet cables may need to be broken as a security precaution. This ensures that malicious devices cannot be spliced into the middle of the cable undetected. Cutting and reconnecting the cable allows you to guarantee that it has not been compromised.

Safety Precautions

When handling network cabling, it’s important to take safety precautions to avoid electric shocks or equipment damage. Here are some key precautions to take:

First, make sure to power down any network devices before working on cables. This includes switches, routers, PoE devices, etc. Cutting or disconnecting a live cable can potentially send a dangerous voltage back through the cable. Powering down equipment helps prevent this.

Second, wear appropriate personal protective equipment (PPE) like safety glasses and gloves. This protects you if any sparking or debris occurs when cutting cables. Thick rubber gloves help insulate you from any live currents.

Third, use a cable tester or multimeter to check for any live current on the cable before cutting. Even if equipment is powered down, residual power could remain in the line.

Also be aware of any nearby power cables when working. Keep a safe distance or cross perpendicularly to avoid interference. Refer to electrical code for proper separation distances, typically at least 6 inches.

Taking simple precautions like these helps ensure safety when modifying network cabling.

Required Tools

To properly break and reterminate a CAT9 ethernet cable, you will need the following tools:

  • Cable stripper – A specialized tool like the trueCABLE Wire Stripping and Cutting Tool is required to neatly and safely strip the cable jacket and inner conductors without damaging the delicate wires.
  • Snips – A good pair of snips or cable cutters like the ones found at Cable Supply will be needed to cleanly cut the CAT9 cable.
  • Crimper – You’ll need a robust crimper designed for CAT9 that can handle the thicker gauge wires. It must be able to securely crimp the new CAT9 connectors.
  • New connectors – Make sure you have enough high-quality CAT9 rated RJ45 connectors for both cut ends of the cable.

Having the proper specialized tools for preparing and terminating CAT9 ethernet cable is essential to creating solid, reliable connections.

Cutting the Cable

Once you’ve identified the cutting point on the CAT9 cable, it’s time to make the cut. Be sure to use a proper cable cutting tool for this step. Wire snips or diagonal cutters work well for cutting network cables like CAT9. Regular scissors or wire cutters may crush the cable rather than making a clean cut.

Mark the cut point with a piece of tape so you know exactly where to cut. Make sure the cut will be straight across all the internal wires. Then, holding the cable firmly, use your snips to make one quick, clean cut through all the wires in one motion. Take care not to twist or bend the cable as you cut. Make the cut as close to perfectly perpendicular across the length of the cable as possible for the best results.

Visually inspect the cut end to ensure all wires have been severed and the cut is clean and even. Repeat the cutting process on the other end of the cable. Once both ends have been cleanly cut, you’re ready to move on to prepping the cable for new connectors.

Prepping the Cable Ends

Once you have cut the CAT9 cable to the desired length, the next step is to prep the cable ends so they are ready for the new connectors. There are a few key steps involved in prepping the cable ends:

Strip cable jacket – Use a cable jacket stripping tool to carefully remove about 1.5 inches of the outer jacket from each end of the CAT9 cable. Be careful not to nick or cut into the internal wiring.

Untwist pairs – CAT9 cables have four twisted pairs of wires inside. Gently untwist the last 0.5 inches of each wire pair so they are ready to be spread out and lined up with the connector contacts.

Trim wires – Use flush cutters to neatly trim the untwisted ends of each wire, leaving about 0.25 inches of exposed copper. Make sure the ends are cut cleanly without fraying.

Once the jacket is stripped, pairs are untwisted, and wires are trimmed, the cable ends will be fully prepped and ready to attach the new CAT9 connectors.

Attaching New Connectors

Once the cable ends have been prepped, you can attach new connectors. This is a critical step that requires care and precision to get right.

First, slide the boot onto the cable. The boot protects the crimped connection and provides strain relief. Make sure the boot is on before crimping.

Next, insert the wires into the connector in the proper order. The wiring order is typically printed on the connector. For Ethernet cables, the order is usually orange/white, orange, green/white, blue, blue/white, green, brown/white, brown. Verify the pairs are lined up correctly.

With the wires fully inserted, use a ratcheting crimping tool to securely crimp the connector. The ratcheting mechanism ensures the proper amount of force is used. Go slowly and make sure the crimp is tight.

Visually inspect the connector to confirm no wires are sticking out and a tight crimp was made. Gently pull on the wires to test they are secure.

Once one end is complete, do the same process to attach a connector to the other end. Be sure to keep track of which end is which.

Attaching quality connectors and crimping properly is critical to creating a solid connection that will provide optimal performance.

Testing the Cable

Once you have attached the new connectors, it’s crucial to test the CAT9 cable to check for any faults and verify performance before deploying it. There are a few key steps to testing the cable properly:

Use a cable tester – You’ll need a dedicated CAT9 cable tester that can verify all four pairs up to the CAT9 specification for speeds up to 40 Gbps. Many basic testers only go up to CAT6 speeds. This Reddit thread recommends only using testers that can validate performance for all pairs at the CAT9 spec.

Check for faults – The cable tester will indicate any wiring faults, crossed pairs, shorts, or other issues that could impact performance. Carefully go through each wire and connection to resolve any faults before continuing.

Verify performance – The cable tester will measure metrics like attenuation, crosstalk, resistance, and signal quality. Compare the results to the CAT9 specification to confirm the cable can support 40 Gbps transmission without excessive interference or signal loss.

Retest as needed – If any part of the cable fails the test, you may need to re-terminate the connectors or replace damaged cable sections until it passes all tests cleanly. Thoroughly testing the cable is crucial for smooth high-speed operation.

Securing the Cable

After replacing a CAT9 cable or installing a new CAT9 cable run, it is important to properly secure the cable to avoid damage or interference that could compromise performance. There are a few key methods for securing CAT9 network cabling (“Top 5 Best Practices for Network Cable Installation”):

Use cable ties or hook-and-loop straps to neatly bundle and attach the cable to permanent structures. Place attachment points at least every 5 feet along the cable run. Avoid over-tightening ties or straps, as this can damage the cable (“Network Cable Installation: Safety and Regulations Tips”).

Utilize cable raceways such as channels or conduits to route and conceal cables along walls, ceilings or baseboards. Properly sized raceways protect cables from inadvertent damage while allowing for easy access.

Use low-voltage cable staples, clamps and hangers to affix cabling to wooden or sheetrock structures. Use care not to overly compress or pierce the cable jacket.

Secure cables to avoid hanging loosely or drooping, which stresses the cable and connectors. Dress cables neatly and avoid tight bends or kinks in the cable.

Label cables at regular intervals for easy identification. Leave some slack at endpoints to reduce strain on connections.

Following best practices for securing CAT9 cabling ensures a reliable, high-performance connection and protects your investment in advanced Ethernet infrastructure.


Properly terminating and installing CAT9 Ethernet cables is critical for ensuring optimal network performance. While the process of breaking and re-terminating CAT9 cabling requires care and the right tools, following basic safety precautions and steps will allow you to successfully break, re-terminate, and test your cables.

In summary, when breaking a CAT9 cable: plan your cable run and measure twice to cut once; use sharp flush cutters to avoid damaging copper strands; strip off the jacket and untwist pairs using a wire stripper; arrange wires in the proper order and trim to equal lengths before inserting into connectors; attach RJ45 connectors properly using a crimping tool; test cable continuity and connectivity; secure and label cable ends; and take care not to bend cables tightly. With some patience and the right techniques, you can customize your CAT9 cabling for a faster, more reliable network.

Proper installation of CAT9 cabling enables you to unlock the full potential 40 Gbps speeds possible over this cable at short distances. While hiring a professional is recommended for large jobs, DIYers can successfully modify and connect CAT9 cabling for smaller home and office networks with the right knowledge. Following best practices step-by-step helps minimize errors and network issues down the road.

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