Patch to allow local port forwarding from an existing connection

[mouring at etoh.eviladmin.org]

[..]
> > or perhaps use readpass.[ch] from -current with echo enabled?
>
> Using read_passphrase() would probably work.  Does it offer any benefits
> over fgets()?  I can't try this, since -current likely won't compile on a
> non-openbsd machine.
>

Why?  OpenSSH portable snapshot compile from Linux to NeXT so far.
http://www.openbsd.com/portable.html  look under 'snapshots' and pick up
the most recently version.  And we should almost insync with the OpenBSD
tree.

- Ben