It's probably not the ports as Hamachi leaves everything wide open. Can you connect to it yourself? What specific error is your friend getting? Can your friend ping you on your Hamachi IP? Is there anything in your log files? Need more details. I actually just figured it out, I played around with t...

I have recently downloaded the eAthena server and, since my isp won't allow me to run a real server, I tried using Hamachi. So I changed all of the IPs in the /conf to my Hamachi IP, but my friend is unable to connect. Could it be the ports that are the problem? I also opened port 6901. Someone plea...