Passing thru Nginx into the FTP server

Hi Team,
Questions
i had a ftp server in local server and trying to publish out site of our network, i edit the conf file as below, but its not working for it.
I can telnet upto the nginx server from outsite of the network, but its not passing thru.

#------------------------------------
# FTP Server Open 221
#---------------
server {
listen 221;
server_name vhome.abct.com;

location / {
proxy_pass ftp://192.168.100.42;
proxy_redirect default;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}

Any help please