The problem is not all systems are *nix. Windows doesn't enforce the <1024 port restriction. The advantage of using port 443 I suppose is that it's so commonly

The problem is not all systems are *nix. Windows doesn't enforce the <1024 port restriction. The advantage of using port 443 I suppose is that it's so commonly used it'll probably (maybe) be tied up with one service or another when it comes to any important host. I guess. But really it's all guesswork and hope when it comes to deciding how to validate host control.