2 Step Ftp

I need to write an ftp script and am using the ftp function in php but I have to ftp through a firewall to backup data and am having trouble.

I first have to ftp to the firewall...this is how it looks at the command line:

ftp gateway.fnet.net
username: user1
password: pass1

Now that I have authenticated to the firewall...I have to ftp to the original host of choice:

Now I am on the host I need to be on.

Can anyone show me what the php would look like for this?

Mine seems to die,...or gets lost after connecting to the firewall.

I have the single step version working in several locations on snet.net, so I know it isn't that...I just don't know how to do the two steps.