["Greg A. Woods" <woods@weird.com>, responding to me]
>> Assuming the network is one for which rsh would be suitable, I can't
>> see any [ssh protocol issues with using cipher "none"].  I'd like a
>> reference to anything anyone has to the contrary.
> If the network is suitable for rsh then just use rsh!

Except that rsh doesn't support some useful things ssh does, such as X
forwarding and port forwarding, that are reasonably likely to be useful
even if the network in question is (believed to be) secure enough for
rsh.

> I.e. you cannot ever safely use "cypher=none" in the way it's
> currently implemented in SSH.

You can in any circumstance where network-level attackers are not part
of the threat model.  (An example might be a building-scale LAN at a
physically secure facility, not networked outside the building by
anything more sophisticated than sneakernet.)  This is not an
exhaustive list; I'm merely pointing out that your statement is
stronger than I believe is justified.

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