This option allows you to designate an external program that will handle the file transfer.
1. You must create a door configuration record for the executable. An external protocol is merely a type of door. For safety purposes the BBS requires all doors to be explicitly configured by the sysop.
2. The external program must support the same communications channel (e.g., telnet, serial port) used by the caller. Note that you may be able to use a 3rd-party driver that simulates the required communications interface. For example, there are several 3rd-party FOSSIL drivers that allow compatible MS-DOS programs to operate over a Telnet connection.