Windows XP SP2 (or later):
Windows asks if the emule (mule) will keep blocking emule the first time it runs. Just click "Unblock".
Note that you can select unblock only if it is an administrator user, and that the "run emule as a non privileged user" feature in the emule option will also be turned off (closed by default).
Windows XP SP1 (or lower version):
Start emule and enter the connection option. After selecting the port you want to use, click "Open WinXP SP1 Firewall port." With all the best, emule will take care of these ports. It is recommended that you click on "Test Port" to confirm that all ports are open and unblocked.
If emule cannot open these ports automatically, you can choose to manually turn the firewall on or off.
The following are detailed guidelines for manually opening these ports:
1. Open emule.
2. Click "Options" > "Connect".
3. Note The TCP client number (default 4662).
4. Also note the UDP port number (default 4672).
5. Turn off the emule and disconnect the network.
6. In Windows XP, click to open the Start menu, and then click My Network Places.
7. Under Network Tasks, click View Network Connections. (Or, right-click My Network Places on the desktop, and then click Properties.) )
8. Right-click the connection for the Internet, and then click Properties.
9. Click the Advanced tab, and then click Settings.
10. Note: If the Settings button is not available, Windows Firewall is not enabled on this connection, and you do not need to open any ports (because they are all open).
11. Click Add to open the new port.
12. In the Description box, type a name, such as "Emule:tcp access."
13. In the computer name or IP address for this service on your network box, type 127.0.0.1.
14. Note: You can specify the IP address of the internal computer. Typically, however, use 127.0.0.1.
15. On the "external port" and "Internal port", type the port number that you noted in #3.
16. Click TCP, and then click OK.
17. Click Add again to open the new port.
18. This time, the name of a UDP is changed, such as "EMULE:UDP access"
19. See #12
20. Now enter the port number noted in #4 in the external port and internal ports boxes.
21. Click UDP, and then click OK.
These firewall rules will be reset once the client port has been changed.