Scanning the whole IPv4 Internet goes pretty fast (I think you can do it on a private subscriber line in a few days). What about IPv6? If I "hide" my service in my public /64 network, can I feel safe against IP scanning? That would be some security by obscurity based on the huge address space (similar to changing default TCP ports)
I think that you'll be safe for outside scans. But IPv6 devices usually talk via ICMPv6 inside their subnet, so if there are other guys on your subnet, they might find out your address. That was the case in some VPS hosters that I used, with tcpdump I was able to see addresses of other nodes.
Given that a fair few devices will fill-in the "interface" bits of the IPv6 address with their MAC (SLAAC), it might be possible to reduce the number of addresses to scan in an IPv6 /64 prefix assuming you know what devices are likely to be used on that network.
It's also very likely your device will be syncing it's clock with an NTP server such as (pool.ntp.org) which can be scraped by running your own stratum 2/3 server and adding yourself to the pool.
while at uni a colleague discovered zmap and scanned 0/0 from the 1gps line for the port of the intel amt management a day after a remote code exec bug was found there. he was just curious but watching the fallout and the angry forwarded mails these days was quite fun...
Any time you connect to a website, you reveal your IPv6 address. I can bet there is a market for making lists of valid IPv6 addresses from web logs and selling those lists to people who want to port scan those hosts.
You might even find big carriers mine IP packets to find IP addresses they can sell.
