OSI LAYER 2 // Data Link Layer

VLAN Hopping

VLAN hopping abuses trunk/access-port configuration or negotiation behavior to reach traffic in another VLAN.

01 // HOW IT WORKS

Mechanism

Misconfigured trunks, native VLAN behavior, or automatic negotiation can create unintended VLAN reachability.

02 // DETECTION

Indicators to watch

Unexpected trunk formation, access ports carrying tagged traffic, native VLAN anomalies, and cross-VLAN traffic where it should not exist.

03 // ATTACK FLOW

Concept diagram

01Access / trunk port↓

02Unexpected VLAN tagging↓

03Cross-VLAN path↓

04Segmentation weakened↓

05Explicit trunk configuration

04 // PREVENTION

Defensive controls

Disable unnecessary trunk negotiation, explicitly configure trunks, avoid native VLAN exposure, use VLAN ACLs, and segment management traffic.

05 // SECURITY TOOL

Recommended security control

Switch configuration audit

Use Packet Tracer/GNS3 for safe demonstrations.

06 // DEFENCE PRACTICE LAB

Defence practice lab

The administrator has not attached a tool link yet. This slot will show “Build Soon” until an external link is configured.

Build Soon

◈

DEFENCE PRACTICE LAB // BUILD SOONThe administrator can add or edit an external defence practice lab link from the private admin portal.

07 // DEFENCE TECHNIQUES

Defence techniques

Defence techniques for this attack will be added by the administrator.

AUTHORIZED LEARNING

All attack descriptions are for defensive education. Test scanning, traffic generation, interception, wireless testing, and vulnerable applications only on systems and networks you own or are explicitly authorized to assess.