Here is a Pre-Built Server for 1.7.3 For Mac
Instructions;
1. Download And Unzip The Folder
2. Place That Folder On the desktop
3. Adjust The Server.Properties file to your Liking
4. Follow A Tutorial On How To Configure Permissions
5. Run The Application "Port Map" (This Does Port Forwarding Pretty much for you )
6. While Port Map is running Run Start.Command (port Map needs to always be running)
7. Wait Until it says Done On the bottom of the terminal window (Can Take Some Time)
8. On the Multiplayer IP box thingy You Connect to "Localhost" and you tell other players to connect to the IP on the Portmap Window

PortMap Tutorial:
1. Click The "+" in the bottom left corner
2. In Local Port Type "25565"
3.Put anything you want in description
The Ip At the Top is the one other players Connect to (Dont forget to add :25565 at the end)


Download:
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If This helped +Rep is appreciated