[tor-dev] Please consider allowing /48 for VirtualAddrNetworkIPv6

[Alex Elsayed]

Hi, I'm using Tor in transparent mode, and I'm running into a rather
inconvenient behavior.

VirtualAddrNetworkIPv6 refuses to parse unless the network address given
is a /40 or broader. However, IPv6 ULA, which makes it very easy to give
Tor its own subnet no-strings-attached, strictly grants a /48 prefix.

As a result, I am faced with a choice between deeply suboptimal options:

1.) Use VirtualAddrNetworkIPv4, as I've done in the past. This results in
_fewer_ addresses being available to Tor than an IPv6 /48, which I feel
illustrates the issues with requiring a /40 quite clearly.

2.) Squat on some portion of the IPv6 address space I don't actually own.
This is entirely unpalatable