7. Security Considerations
Traditionally, Layer 2 networks can only be attacked from 'within' by rogue end points -- either by having inappropriate access to a LAN and snooping on traffic, by injecting spoofed packets to 'take over' another MAC address, or by flooding and causing denial of service. A MAC-over-IP mechanism for delivering Layer 2 traffic significantly extends this attack surface. This can happen by rogues injecting themselves into the network by subscribing to one or more multicast groups that carry broadcast traffic for VXLAN segments and also by sourcing MAC-over-UDP frames into the transport network to inject spurious traffic, possibly to hijack MAC addresses.
This document does not incorporate specific measures against such attacks, relying instead on other traditional mechanisms layered on top of IP. This section, instead, sketches out some possible approaches to security in the VXLAN environment.
Traditional Layer 2 attacks by rogue end points can be mitigated by limiting the management and administrative scope of who deploys and manages VMs/gateways in a VXLAN environment. In addition, such administrative measures may be augmented by schemes like 802.1X [802.1X] for admission control of individual end points. Also, the use of the UDP-based encapsulation of VXLAN enables configuration and use of the 5-tuple-based ACL (Access Control List) functionality in physical switches.
Tunneled traffic over the IP network can be secured with traditional security mechanisms like IPsec that authenticate and optionally encrypt VXLAN traffic. This will, of course, need to be coupled with an authentication infrastructure for authorized end points to obtain and distribute credentials.
VXLAN overlay networks are designated and operated over the existing LAN infrastructure. To ensure that VXLAN end points and their VTEPs are authorized on the LAN, it is recommended that a VLAN be designated for VXLAN traffic and the servers/VTEPs send VXLAN traffic over this VLAN to provide a measure of security.
In addition, VXLAN requires proper mapping of VNIs and VM membership in these overlay networks. It is expected that this mapping be done and communicated to the management entity on the VTEP and the gateways using existing secure methods.