Failed to start FTP server :
Job for proftpd.service failed because the control process exited with error code. See “systemctl status proftpd.service” and “journalctl -xe” for details.
The journalctl -xe shows some usefull info:
proftpd: fatal: SFTPHostKey: Unable to use ‘/etc/ssh/ssh_host_rsa_key’ as host key, as it is group- or world-accessible on line 436 of ‘/etc/proftpd.conf’
Solution:
Locate the .conf file:
/etc/proftpd.conf
At the end of the .conf file comment the lines…
# SFTPHostKey /etc/ssh/ssh_host_rsa_key
# SFTPHostKey /etc/ssh/ssh_host_dsa_key
Start ProFTPD Server
et voilà!