Problem
I have a server running vsftpd, and I have this problem:
[root@server ~]# ncftp -u username localhost
NcFTP 3.2.4 (May 16, 2010) by Mike Gleason (
http://www.NcFTP.com/contact/).
Connecting to 127.0.0.1…
Welcome to this FTP server.
Permission denied.
Sleeping 20 seconds...
Solution
In my case I had trailing spaces after the username in the userlist file. (The userlist file was generated in a hurry while porting from a different service.)