Basic Setup so users can connect from the Internet
FTP connections within your local network usually work without any problems. However, when you want the FTP server to be available outside of your local network, additional steps are often necessary to make the server visible to the outside world. The following steps are usually required to allow Cerberus FTP Server to be accessed from the Internet:
Step 1 – Control Connection
The control connection port Cerberus FTP Server is listening on needs to be forwarded from your router to the machine hosting Cerberus. The default port for FTP and, that Cerberus listens on, is port 21. Consult your router documentation for instructions on how to setup port forwarding. Finishing this step will allow Internet users to establish a connection with your server. The next step is making sure passive mode is configured so that directory listings and file transfers work.
Step 2 – Passive Mode
To allow passive mode to work properly, you must forward the passive range of ports from your router to the machine running Cerberus. See “My IP address begins with 192.168.xxx.xxx. Is there anything special I have to do for people to see my FTP Server on the Internet?” for detailed instructions on how to make sure passive mode is setup properly. If you don’t perform this step, users may be able to login but directory listings may hang and timeout.
Step 3 – Firewall
Make sure any firewalls you are running are allowing connections on port 21. Cerberus will automatically attempt to add itself to the Windows Firewall Exception list (you will be prompted to allow this). However, you may still have to manually add an exception to allow port 21 connections into your computer.
See also Allowing external user to connect