At this point, the VLAN 20 tag is still intact and has not been inspected by the first switch. On the trunk port, the VLAN 10 tag is stripped, and the packet is not retagged because it is part of the native VLAN. The switch forwards the packet out on all VLAN 10 ports after stripping the VLAN 10 tag. The switch sees that the frame is destined for VLAN 10, which is the native VLAN.
Step 2. The frame arrives on the switch, which looks at the first 4-byte 802.1Q tag. The inner tag is the victim VLAN in this case, it is VLAN 20. (A switch should not receive a tagged Ethernet frame on an access port.) For the purposes of this example, assume that the native VLAN is VLAN 10. The assumption is that the switch processes the frame received from the attacker as if it were on a trunk port or a port with a voice VLAN. The outer header has the VLAN tag of the attacker, which is the same as the native VLAN of the trunk port. Step 1. The attacker sends a double-tagged 802.1Q frame to the switch. This attack takes advantage of the way hardware on most switches operates. Double-Tagging AttackĪnother type of VLAN hopping attack is a double-tagging (or double-encapsulated) attack. #Which method would mitigate a mac address flooding attack how to#
How to Configure Switch to Mitigate VLAN Attacks. The attacker can then access all the VLANs on the victim switch from the rogue switch.
Introducing a rogue switch and enabling trunking. From here, the attacker can send traffic tagged with the target VLAN, and the switch then delivers the packets to the destination. Spoofing DTP messages from the attacking host to cause the switch to enter trunking mode. Disable unused ports and put them in an unused VLAN.Ī VLAN hopping attack can be launched in one of two ways:. S5(config-if-range)# switchport trunk native vlan 900 S5(config-if-range)# switchport nonegotiate S5(config-if-range)# switchport mode trunk Set the native VLAN to be something other than VLAN 1 and to be set on an unused VLAN using the switchport trunk native vlan vlan_number interface configuration mode command. Disable DTP (auto trunking) negotiations on trunking ports using the switchport non-negotiate interface configuration command. S5(config-if-range)# switchport access vlan 899 
Manually enable the trunk link on a trunking port using the switchport mode trunk interface configuration command. S5(config-if-range)# switchport mode access Disable DTP (auto trunking) negotiations on non-trunking ports by using the switchport mode access interface configuration command. The best way to prevent basic VLAN hopping attacks: The basic concept behind all VLAN hopping attacks is for an attacking host on a VLAN to gain access to traffic on other VLANs that would normally not be accessible. The VLAN hopping is a computer security exploits, a method of attacking networked resources on a virtual LAN ( VLAN). The Switch spoofing is a type of VLAN hopping attack, A switch interface which is connected to an end device (a computer or a printer) are normally in access mode and that end device will have access to its own VLAN. A specific type of VLAN threat is a VLAN hopping attack. The VLAN architecture simplifies network maintenance and improves performance, but it also opens the door to abuse. Do you know what are the best ways to mitigate VLAN attacks in the network switching? Here we just explain VLAN threats and mitigate VLAN attacks.
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