mk6i-open-oscar-server/docs/RENDEZVOUS.md

Configuring File Transfer Over The Internet

Context

In the OSCAR protocol, Rendezvous is a mechanism that lets two AIM clients exchange the necessary information to establish a direct, peer-to-peer connection—typically used for file transfers.

Back in the early 2000s, most computers were assigned a public IP address directly from their ISP. As a result, when one AIM client sent its IP address to another, that address was routable on the public Internet. Today, almost everyone is behind a router performing Network Address Translation (NAT). Consequently, the sender’s machine usually only has a private IP address (e.g., 192.168.x.x), which cannot be reached directly over the Internet.

To work around this limitation, Open OSCAR Server can substitute your client’s private IP address with the server’s view of your public IP address. However, you still need to configure port forwarding on your router to ensure that incoming Rendezvous connections (for file transfers) are routed to the correct machine.

Send File Setup

This guide explains how to configure your Windows AIM client to send files over the Internet using the Send File feature. If you only need to receive a file, no additional setup is required.

Caveats

• Same LAN Scenario
  If both Open OSCAR Server and your AIM client are on the same local network (LAN), you do not need these steps.

• Mixed LAN and Internet
  If the sending client and the server are on the same LAN while the receiver is on the Internet, this guide may not work as intended.

• Security Notice
  Rendezvous makes your IP address visible to the recipient. Opening a port on your home network allows inbound Internet traffic to reach your computer on that port. Use careful judgment and consider the security implications before proceeding.

1. Configure AIM Port

1. Open the AIM Preferences window.
2. Select File Transfer from the sidebar or menu.
3. In the Port number to use field, enter a high port number such as 4000.

2. Set Up Router Port Forwarding

1. Log in to your router’s admin interface.
2. Create a new port forwarding rule:
   • Forward TCP port 4000 (or the port you chose)
   • Send that traffic to the local IP address of the computer running AIM
3. Save or apply the changes.

3. Send a File

Once everything is set up:

1. Start an IM with a friend.
2. Go to File > Send File... (or use the appropriate menu option in your AIM client).
3. Choose the file you want to send.
4. Your friend should now receive a prompt to accept or decline the file.

If the receiver is on the Internet and your port forwarding is correct, the direct file transfer should succeed.