The server JAR is different from the client JAR. To host a 1.5.2 server:
You can now invite friends running the same 1.5.2 client.
Launch Forge once. Then go to .minecraft/mods/ (create the folder if missing).
If you are looking to run a high-performance server with plugins (which is what people usually use Paper for), you must use Spigot for version 1.5.2.
The server JAR is different from the client JAR. To host a 1.5.2 server:
You can now invite friends running the same 1.5.2 client.
Launch Forge once. Then go to .minecraft/mods/ (create the folder if missing).
If you are looking to run a high-performance server with plugins (which is what people usually use Paper for), you must use Spigot for version 1.5.2.