15. Can I force ProFTPD to listen on only one IP?
 
Sort, of it's not quite as clean as the socket binding under Apache but the principle works something like this.
Standalone mode
 
To listen on the primary IP of a host use the SocketBindTight directive
 
To listen on a interfaces which are not the primary host interface use the SocketBindTight directive, place your server configuration in a <VirtualHost ftp.mydomain.com> block and use "Port 0" for the main host configuration and and "Port 21" inside the VirtualHost block.
inetd
 
There are two approaches possible, the first is to use the patch from Daniel Roesen <droesen@entire-systems.com> (check the mailing list archives).
 
The second method is to run ProFTPD from xinetd (http://synack.net/xinetd/), a more advanced replacement of inetd. An entry for this in xinetd.conf would be something like this:
 
service ftp
{
        disable = no
        flags   = REUSE
        socket_type             = stream
        wait                    = no
        user                    = root
        server                  = /usr/sbin/proftpd
        log_on_success          += DURATION USERID
        log_on_failure          += USERID
        nice                    = 10
 #bind   = [IP to bind to]
}