NMAP Penetration Testing

I was just trying an NMAP scan (using the free Network Security Toolkit running from a CD) against the IP address on my external interface on a couple of our Fortinet boxes with fairly recent firmware. NMAP shows 10 ports are open including 443/tcp, 21/tcp, 25/tcp, 80/tcp, 443/tcp, 110/tcp, 5190/tcp, 119/tcp and 5050/tcp - this was by doing a SYN stealth scan with NMAP. Does anybody know why there are 10 ports open? Even with no inbound rule at all and ping disabled and all external interface administrative ports turned off these ports show up as open and if you manually ftp to the external port, it does connect so FTP is kind of open - again does anybody know why? Can somebody else try this on their Fortinet boxes and let me know what you see?