I am new in metasploit. I get the basic concept of exploiting a system or whatever your trying to do. You find a vulnerability in a system, you use an exploit or make one. Doing that on your local network is easy, but doing that on a computer across the globe is something else. There is the system's firewall, the router's firewall, and there might be other programs that keeps you away from success. On top of that, the exploit may not succeed. I get that the previous theories may block the process, but I don't know how Metasploit tells you that. I tried to exploit a machine running Windows XP that is not in my network with netapi exploit (the firewall of that machine is off), but I got errors like the connection refused by the host. I tried another exploit that uses windows/meterpreter/bind_tcp payload but i get: failed to bind to -my IP address_the port i used-.
So am having some real rough times using metasploit on global ipv4 addresses. So telling me the process of attacking a system across the globe and the types of problems I could face with metasploit and how to fix them will be really appreciated.