> I wonder whether other OS's have supported anything like that.
I don't think I've seen it, but I don't see everything, and it'd be pretty esoteric. From my memory of working with the FreeBSD tcp stack, I suspect it wouldn't be too hard to make something like this work there, too; other than the security aspects, but could probably do something like ok to 'repair' a connection that matches a listen socket you also pass or something. But you'd really need the use case to make the hassle worth it, and I don't think most regular server applications are enough to warrant it.
I don't think I've seen it, but I don't see everything, and it'd be pretty esoteric. From my memory of working with the FreeBSD tcp stack, I suspect it wouldn't be too hard to make something like this work there, too; other than the security aspects, but could probably do something like ok to 'repair' a connection that matches a listen socket you also pass or something. But you'd really need the use case to make the hassle worth it, and I don't think most regular server applications are enough to warrant it.