When i have  connecting  sftp in filezilla for upload files into server,  it could not be connected,  after that check in secure log file  in server showing below error,

 # tail –f /var/log/secure


Apr  1 16:53:42 host proftpd[1234]: host.domain.com (192.168.0.1[192.168.0.1]) - USER proftpd (Login failed): Invalid shell: '/bin/false'

find the protpd.conf file, If unable to find the proftpd configure file you can find it by using below command,
 
# proftpd –V


Configure : /etc/local/proftpd.conf
# vi /etc/local/proftpd.conf

Suppose the /bin/false is not listed in your /etc/shells file.    For proftpd, it shouldn't even be checking this,  


RequireValidShell  no

Append following line in proftpd.conf

Restart proftpd to take effect changes we've done..
 
# pkill -9 proftpd  

# proftpd
 

Note : Check the proftpd  status  with netstat command.
 
# netstat -lnp | grep proftpd


tcp    0    0 0.0.0.0:11513      0.0.0.0:*       LISTEN      14538/proftpd


I hope you have never facing this connection issue.