If you read the doco (like “man gai.conf”) you would be forgiven for thinking that the contents of /etc/gai.conf controlled source and destination address selection in IPv6. You would be wrong.
In a previous article, I discussed how IPv6 source address selection worked. Normally it all Just Works, but there are several situations where you may want or need to control the address selection process. In this article, we’ll look at why you might want to control source address selection, and how you can do it.
Source address selection must be very irritated; destination address selection gets all the press coverage.
This article will start to redress the balance, by talking about what source address selection is, why it is needed, and how it works. If you want the nitty-gritty, check out RFC 6724 (which obsoletes RFC 3484).