What is VLAN double tagging?
Double tagging occurs when an attacker adds and modifies tags on an Ethernet frame to allow the sending of packets through any VLAN. This attack takes advantage of how many switches process tags. Most switches will only remove the outer tag and forward the frame to all native VLAN ports.
What does double tagging mean?
Double-tagging is a method by which the attacker tries to reach a different VLAN using the vulnerabilities in the trunk port configuration. This is achieved by first making note of the native VLAN configured on the trunk link connected to the switch ports.
Can a VLAN be both tagged and untagged?
Best Practices. VLAN-enabled ports are generally categorized in one of two ways, tagged or untagged. These may also be referred to as “trunk” or “access” respectively.
What is 802.1Q double tagging?
In a double tagging attack, an attacker connected to an 802.1Q-enabled port prepends two VLAN tags to a frame that it transmits. The frame (externally tagged with VLAN ID that the attacker’s port is really a member of) is forwarded without the first tag because it is the native VLAN of a trunk interface.
Can you spoof VLAN?
Switch spoofing It is possible only when using the dynamic auto or dynamic desirable default switch modes. Once there is a trunk connected to the computer, the attacker gains access to all VLANs. This is a misconfiguration as interfaces should not be configured to use the dynamic switch port modes.
How does switch spoofing work?
Switch spoofing is a type of VLAN hopping attack that works by taking advantage of an incorrectly configured trunk port. By default, trunk ports have access to all VLANs and pass traffic for multiple VLANs across the same physical link, generally between switches.
Can a port have multiple untagged VLANs?
While it is possible to have more than one untagged VLAN on a port, this is typically not done. It’s easy for a switch to egress multiple VLANs untagged, it would not know what to do with the ingress traffic as the VLAN it originated from would be indeterminable.
What is the purpose of 802.1Q tagging?
The 802.1Q tagging protocol allows the Ethernet frame size to increase by four bytes to a range of 68 to 1522 bytes. This size increase is due to the insertion of a four-byte VLAN tag into the frame. The tags, which include a VLAN Identifier (VID), are attached to each Ethernet frame by MAC address.