Reverse ssh tunnel

ssh -fNR 2222:localhost:22 me@MyServer

similar to -fNL for for reverse tunneling instead.

REFERENCE:
http://portable.easylife.tw/2043 (Chinese)

ssh keep-alive

/etc/ssh/sshd_config:

ClientAliveInterval 60

as well as other 'KeepAlive' should be turned on.

REFERENCE:
http://madphilosopher.ca/2005/07/an-ssh-keep-alive-tip/

Match Group ssh/sftp chroot

[...]
Match Group users
    ChrootDirectory /home
    AllowTCPForwarding no
    X11Forwarding no

REFERENCE:
http://www.howtoforge.com/restricting-users-to-sftp-plus-setting-up-chrooted-ssh-sftp-debian-squeeze