Linux/Ubuntu :: pure-ftpd does not allow login to user with /usr/sbin/nologin shell

Expectations:
You have created a user with /usr/sbin/nologin shell (ftp-only user) in Linux/Ubuntu.
If you SSH to the box with this username and password it should not work.
If you FTP to the box with this username and password it should.

Symptoms:
Pure-ftpd does not permit login if the shell is set to /bin/false or /usr/sbin/nologin.
If you change the shell to /bin/bash it works.


Connected to localhost.
220---------- Welcome to Pure-FTPd [privsep] [TLS] ----------
220-You are user number 2 of 50 allowed.
220-Local time is now 17:53. Server port: 21.
220-This is a private system - No anonymous login
220-IPv6 connections are also welcome on this server.
220 You will be disconnected after 15 minutes of inactivity.
Name (localhost:root): ftponly
331 User ftponly OK. Password required
Password:
530 Login authentication failed
Login failed.
Remote system type is UNIX.
Using binary mode to transfer files.

Solution:

You need to add the nologin or false shell to the file /etc/shells.

root@box:/# cat /etc/shells

# /etc/shells: valid login shells

/bin/csh

/bin/sh

/usr/bin/es

/usr/bin/ksh

/bin/ksh

/usr/bin/rc

/usr/bin/tcsh

/bin/tcsh

/usr/bin/esh

/bin/dash

/bin/bash

/bin/rbash

/usr/bin/screen

/bin/false

/usr/sbin/nologin