I will help Emistry for the IP stuff.
You can use no-ip to get rid of dynamic IP address. No-IP
Register there, take any name, and download their Dynamic Update Client
Install it on your computer and put a shorttcut to the startup folder, so it will update the info to No-IP everytime you start your computer up.
Then,
On your Server files:
on char_athena.conf:
login_ip: 127.0.0.1
char_ip: your_noip_url.no-ip.org
*if yours is purplero.servegame.com, then, use it.
on map_athena.conf:
char_ip: 127.0.0.1
map_ip: your_noip_url.no-ip.org
Then, in your client, diff it with:
[Enable DNS Support]
after that, change the content of clientinfo.xml:
<address>your_noip_url.no-ip.org</address>
wait~ it was not the end. but, I believe you can do it.
Reserve an IP address, assign 1 IP to your computer on your router (I mean, open 192.168.1.1 > DHCP (or something) configuration > assign an IP to your computer) then, open the LAN settings in your computer's OS, put the same IP address. e.g: 192.168.1.6. subnet mask: 255.255.255.255, default gateway: look at the "details" box before you click the "properties" button (windows vista / 7). Primary and Alternate thing also available on the dialog box where you found the Default Gateway thing.
forward port 80,3306,5121,6121,6900 to your computer's LAN IP address.