built-in sftp chrooted sftp

README.txt

user1,user2 no password login
user3 both

classical $home/.ssh usage
$home must be root owned
only $home/subdirs as chrooted-user could be writeable

note: recent openssh server require password (random it)

group

#/etc/group
sftp:x:4099:user1,user2

passwd

#/etc/passwd
user1:x:4000:4099:user1:/sftp/user1:/bin/false
user2:x:4001:4099:user2:/sftp/user2:/bin/false
user3:$xxxxxxxx/:4002:4099:user3:/sftp/user3:/bin/false

sshd_config

#/etc/ssh/sshd_config
Subsystem sftp internal-sftp

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