ange-ftp-gateway-prompt-pattern is a variable defined in `ange-ftp.el'.
Its value is
]*[#$%>;] *"

Regexp matching prompt after complete login sequence on gateway machine.

A match for this means the shell is now awaiting input. Make this regexp as
strict as possible; it shouldn't match *anything* at all except the user's
initial prompt. The above string will fail under most SUN-3's since it
matches the login banner.

You can customize this variable.