Hack a Cisco Switch with a Raspberry Pi - CCNA Security - CCNP Security - Network+

About this video

In his network closet, Chuck demonstrates a VLAN hopping attack using a Raspberry Pi he calls Malcolm, running Kali Linux and accessed via SSH and VNC. He explains that a VLAN is a virtual LAN that partitions a switch into separate broadcast domains, so hosts in VLAN 1 cannot reach VLAN 2 at layer 2 without routing. Ports are either access ports carrying one VLAN or trunk ports carrying multiple VLANs using 802.1q tagging. Plugged into port 14, initially shown as an access port in VLAN 1, Malcolm uses the Yersinia tool to launch a DTP (Dynamic Trunking Protocol) switch-spoofing attack, selecting the option to enable trunking and impersonating a switch. Checking the switch afterwards shows interface FA 1/0/14 has become a trunk with access to all VLANs, and switching Yersinia to 802.1q mode lets him listen to broadcasts, see IP addresses across VLANs, and assign himself an address in a VLAN of his choosing. He notes the attack can also be run entirely in GNS3 and teases that a single default security practice can prevent it.

Key takeaways

• VLANs provide separation inside a switch, but that separation depends on ports staying correctly configured as access versus trunk
• The demonstrated method is switch spoofing via DTP: the attacker negotiates an access port into becoming a trunk port
• The tool used is Yersinia on Kali Linux on a Raspberry Pi, and the attack itself took only a few seconds in the demo
• Verification is by CLI: show interface status changes port 14 from VLAN 1 access to trunk, and show interface trunk confirms it
• Once trunking, the attacker can observe broadcasts and IPs across VLANs and join any VLAN by assigning a matching IP address

Episode details: published April 17, 2018 · 8:31 long. Summary written by Self Growth Videos from the episode itself. Business results and any income figures mentioned are NetworkChuck’s own claims, shared for education — they are not typical or guaranteed.

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