Using a unix based text editor such as vi or nano, open the cc-ftp configuration file "/usr/local/centovacast/etc/cc-ftpd.conf", and locate the following line:
FTP_PORT=21
Change it to:
FTP_PORT=2121
Finally, if you are using a firewall make sure to add your new cc-ftp port to the exception list, and start cc-ftp using: /etc/init.d/centovacast start-ftp