On Jan 4, 2018, at 10:17 AM, Karl Denninger <k...@denninger.net> wrote: > > I've written a fair bit of code that binds to both Ipv4 and v6 for > incoming connections, using two sockets (one for each.) > > Perusing around the 'net I see an implementation note written by IBM > that implies that on their Unix implementation you can set up an INET6 > listener and it will open listeners on *both* IPv4 and v6; you code it > as an Ipv6 socket/bind/listen/accept, and if an Ipv4 connection comes in > you get a prefix'd IPv4 address back when you call getpeername(). > > This would obviously shorten up code and remove the need to open the > second listener socket, but playing with this on FreeBSD it doesn't > appear to work -- I only get the IPv6 listener in "netstat -a -n" > showing up and as expected a connection to a v4 address on that port > fails (refused, since there's no listener.) > > Is this something that *should* work on FreeBSD?
It works. We do it all the time. You either have to set the sysctl: net.inet6.ip6.v6only=0 which you can do in /etc/sysctl.conf or with the sysctl utility, or, in your program, use setsockopt to turn off the V6ONLY option, e.g.: setsockopt(s, IPPROTO_IPV6, IPV6_V6ONLY, &(int){0}, sizeof (int)); // Turn off v6-only We use the first method, which is broken in FreeBSD 11.1 prior to patch level 5 or 6, I can’t remember which, but works in all others. The second method is considered to be more portable. FWIW, Linux, by default, sets v6only off, so it doesn't require anything special. _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"