The short answer is that FTPS and firewalls (and devices performing NAT) do not interact well. The control connection happens on a well-known port, and has no issues; it is the data connection that poses problems for FTP-aware firewalls.
In a non-FTPS session, the firewall can inspect the FTP server's responses on the control connection to a client's PASV or PORT command, and thus know which on which ports/addresses the data connection will be established.
In an FTPS session, though, those control connection messages are encrypted (that is the point of using FTPS, right?), and so the FTP-aware firewall cannot peek. Hence, it cannot know which on which ports the data connection will be established. For firewalls that are configured to always allow a certain range of ports (such as might be configured using the PassivePorts directive), FTPS should function without issue.
edtFTPD is based on proFTPD, so you can use PassivePorts as described here
http://www.proftpd.org/docs/directives/ ... Ports.html
and get the firewall configured to permit these ports.
The client must be transferring in passive mode.
The UNIX server is the client using Microlite Backup Edge to connect using FTPS and backing up the UNIX server remotely on the edtFTP Windows 2003 server. Everything was fine till the customer put a firewall in between the UNIX server and edtFTP server. I am not sure what to tell him to do on the firewall so our backups will work again.
