I like vsftpd because it is fairly easy to work with. To set up a server and some ftp accounts:  

sudo apt-get install vsftpd

Edit /etc / vsftpd.conf.

listen=YES

anonymous_enable=NO

local_enable=YES

write_enable=YES

local_umask=022

dirmessage_enable=YES

use_localtime=YES

xferlog_enable=YES

connect_from_port_20=YES

chroot_local_user=YES

secure_chroot_dir=/var/run/vsftpd/empty

pam_service_name=vsftpd

rsa_cert_file = / etc / ssl / private / vsftpd.pem

pasv_enable=YES

tcp_wrappers=YES

pasv_min_port = 15393

pasv_max_port=15394

port_enable=YES

pasv_address = # server's EXTERNAL IP #

Open up 15393-15394 and 20-21 the firewall.

FTP accounts set up with the simplest: