Since I've been immersing myself in IPv6 I've naturally becomeinterested in finding out the IPv6 addresses of hosts, which means getaddrinfo() . In many ways, getaddrinfo() is a great API; it'swonderfully tuned for giving you exactly the information you need inorder to make connections to places. In other ways, it's less than idealand how to use its API is unclear.

(For the rest of this, I'm going to assume that you'

The common garden variety configuration file is generally terrible;hard to write, hard to read, and hard to use. That's because they'vegenerally been designed wrong, with the wrong purpose.

Much like programming languages, very few people create configurationsystems with the goal of communicating with both the program and otherpeople; instead they are almost always aimed just towards communicatingwith the program. When you are just communicating with the program, allsorts of things can be implicit , cryptic,and focused on the

First, the brief review. Linux's net.ipv6.bindv6only sysctl controlswhether an IPv6 socket can also accept IPv4 traffic (with IPv4 mappedaddresses), or whether it binds only to true IPv6 traffic. So if youwant to turn off dual binding (which I think youshould), you turn this sysctl on and then run around fixing up things towork.

Except there's a gotcha. Whether IPv6 sockets can also talk IPv4 isactually a