Re: Disabling temporary addresses by default?

[Ted Lemon <[e-mail]>]

On Jan 28, 2020, at 10:31 AM, Lorenzo Colitti <[e-mail]> wrote:
> For outgoing connections, that's what we do in IPv4, and it has the same disadvantages. I'd say the most important are: a) it breaks protocols that encode the IP address in the stream and requires those protocols to implement NAT traversal, and b) it requires periodic keepalives to keep the mapping alive.

Hopefully we’re not doing (a) anymore, although I suppose maybe SIP still does.  So for protocols that do this, you don’t get privacy.   Since HTTP doesn’t do it, that takes care of 99.99% of the use cases an end user cares about.   O(0) end users use SIP or FTP.

As for (b), sure, but that’s not really such a big deal in modern times.   Just keep a fast working set and a slow swapped-out set; if something hasn’t been active in the past fifteen minutes, remove it from the working set to keep lookups fast, but if you get something targeted for an unknown address that looks sensible, as time permits look it up in the slow table.  If somebody DDoSes you, long-lived idle connections might suffer, but otherwise it works, and when you are being DDoSed, you can easily do lookups at whatever rate is appopriate, and drop traffic to unknown addresses in excess of that rate on the floor.

Of course, all of this assumes that router vendors get it right (Hi, UNH!).