Limit number of simultaneous sftp-server connections from same ip

[Ben Lindstrom]

>>> While limiting the use of sftp-server I want to retain _full_
>>> access to normal (shell-like) connections over sshd without limits.
>>> 
>> Add the wrapper to the subsystem directive in sshd_config.

Not really. If they have full ssh shell access they can by-pass this wrapper 
without much of an issue.  This only keeps the honest people honest.

- Ben