Portable Modern Network Programming (cont.)

server side
make all sockets provided by getaddrinfo(3) ready for accepting
set IPV6_V6ONLY if available (#ifdef)
don't consider the error of setsockopt(2) as fatal
don't consider the error of bind(2) as fatal (*)
Don't forget IPv4-mapped addresses 
*: if you're okay not to support older linux, it is okay to consider it as fatal