OpenWRT as reliable and secure SFTP server

readme.txt

$ opkg update
$ opkg install openssh-server openssh-sftp-server

# disable built-in dropbear
$ /etc/init.d/dropbear disable
$ /etc/init.d/dropbear stop

# enable full openssh server
$ /etc/init.d/sshd enable
$ /etc/init.d/sshd start

# disable dropbear default instance
$ uci del dropbear.cfg014dd4
$ uci commit

# create sftp group
sftp:x:4099:sftp
$ nano /etc/group

# configure ssh server
$ nano /etc/ssh/sshd_config

# comment
Subsystem sftp /usr/lib/sftp-server
# add
Subsystem sftp internal-sftp

# add 
Match Group sftp
        ForceCommand internal-sftp
        ChrootDirectory %h
        AllowTcpForwarding no
        PermitTunnel no
        X11Forwarding no
        AllowAgentForwarding no

# restart server
$ /etc/init.d/sshd restart

# for each user (adjust $username, $dir and $i)

# add users as : 
# $username:x:400$i:4099:$username:/$dir:/bin/false
$ nano /etc/passwd

# add to sftp group (at the end of line, comma-separated)
$ nano /etc/group

# if we want password login
$ passwd $username

# create required file
$ mkdir /$dir/.ssh
$ touch /$dir/.ssh/authorized_keys
$ mkdir /$dir/data

# create key
$ dropbearkey -t rsa -f /$dir/.ssh/id_rsa

# set owner permisisons
$ chown $username:sftp -R /$dir
$ chown root /$dir

# restart server
$ /etc/init.d/sshd restart