In this way, many users and clients will operate with IPv6 without touching the productive LAN. We decided to activate IPv6 on the guest/ BYOD Wifi. In this blog post I will present a use case for storing these bindings, the concept of the DAD messages, a Tcpdump script for doing this job, and the disadvantages and alternatives of this method.Ī customer wanted to test IPv6 in order to achieve knowledge for the IT admins.

This can be done with a small Tcpdump script on a dedicated Ethernet interface of a Linux host. The mapping of “identity to IP” is not done automatically somewhere.Ī simple way to overcome this issue is to install a service that captures Duplicate Address Detection (DAD) messages from all clients on the subnet in order to store the bindings of MAC and IPv6 addresses. That is, a subsequent analysis of network behaviour corresponding to concrete IPv6 addresses and their client machines is not possible anymore. In the IPv6 world, if SLAAC (autoconfiguration) is used, no network or security device per se stores the binding between the MAC (layer 2) and the IPv6 (layer 3) addresses from the clients. In the legacy IPv4 world, the DHCP server allocates IPv4 addresses and thereby stores the MAC addresses of the clients.

How to convert mac address to ipv6