Protocol "41" Income Blocked


I’ve been using Comodo for years. It is really great.
But I met something that never happened before, and it indeed terrified me.

My rule is Block all IP in for ANY protocol, and the applications use Outgoing only.

Comodo block log showed 5 times of blocking to Protocol “41”
(NOT port, the place should be TCP, UDP or ICMP etc.)
And no port, it’s empty.
It seems like IPv6.

The source IP is
They should be belonged to Microsoft…

I have no any clue about this creepy thing, any idea?


Please read this post here:


I’m using XP right now, should I do anything to react this?
Would it become a threat?
And… why microsoft?

Did you install IPv6 support then? by default it’s not available on XP AFAIK.

The system files (dll…) are installed by default, only the tcp/ip protocol itself is not, but is very easy to install from the command line “ipv6 install” without even specifying the path, as ipv6.exe is default installed under \system32.