So you have run an Nmap scan and you have open port 21 that has been identified as being ftp. What next?
Run the NMap scan using the -A flag. This will tell you if the ftp allows anonymous login.
The very simplest command you can enter at the prompt is:
ftp 172.16.195.202
Replace the IP address above with the IP address of the target machine.
If a successful connection has been made you will now be prompted to enter the username. If the NMap scan indicates that anonymous login is permitted simply type:
anonymous
If you know the ftp username enter the following:
ftp username@172.16.195.202