SSH, The Secure Shell: The Definitive Guide, 2nd Edition

Identity and Authorization Files, OpenSSH

~/.ssh/authorized_keys key options: use one public key per line, preceded by options.

Option	Meaning
command=”Unix shell command"	Specify a forced command
environment=”variable = value"	Set environment variable
from=host_ or_ ip_address_specification	Limit incoming hosts
no-agent-forwarding	Disable agent forwarding
no-port-forwarding	Disable port forwarding
no-pty	Don’t allocate TTY
no-x11-forwarding	Disable X Window forwarding
permitopen ="H:P"	Permit forwarding to local port P from remote host H