Open FTP (or SFTP) protocol in port forwarding

holyhope

Hi to all, I'm using Zyxel router of my internet provider.
I want to port forward with FTP protocol. In the configuration I can only forward port via TCP, UDP or TCP+UDP but there isn't a way to open an FTP protocol.
I have a NAS in my house, connected to my router via ethernet, and I need to open FTP (or SFTP) protocol for accessing from extern of my house.
I have a service that allow me to connect to my ip public ip address and i choose one random port for ftp service. 
with TCP and UDP port I have no problem I can access to my computer web page but I can't choose ftp option.
So how I can open ftp (or sftp) protol in my zyxel router?
thanks and have a nice day
Massimiliano

Snow

What model are you using?
If there is a web gui, there might be somewhere else to open the port.

Mijzelf

You are mixing things up. TCP and UDP are low level protocols, while FTP and SFTP are highlevel, and both run on top of TCP.

Having said that, FTP is a difficult protocol to forward, it doesn't need just a single forward, but a whole range of ports. SFTP is easier, just forward TCP on the right port. (If it is actually SFTP. FTPS is basically FTP with an encryption layer, and is as difficults as FTP)