Today I had an issue at a customer site when setting up DIrectAccess… I could not get Teredo to work. I fired up Wireshark on the server but could not see any Teredo traffic. There is an external firewall between the DA server and Internet but it is transparent so the traffic should reach my server.
At home in my lab everything is running in Hyper-V including my lab router (pfSense) so when I got home I connected the customer laptop I borrowed to an external port on my lab network and then I configured port mirroring on the LAN port of the router. I then installed Wireshark on one of my other virtual machines. This way I can verify traffic coming into the firewall.
When I was able to verify the traffic going into the firewall I switched and monitored the external interface on the firewall to verify that I also had Teredo on the external side.