The requested release binding is patch.  

The ssh_config(4) file is Committed, this case is about an option 
that will assist with sharing an ssh_config(4) file with older releases.

ABSTRACT
--------

This case concerns ssh(1)'s behaviour in the face of unknown
configuration options.

It's been recently discovered that the current behaviour (exit with an
error message) makes per-user ssh configuration files (see ssh(1) and
ssh_config(4)) not extensible in compatible ways.

This behaviour is inherited from OpenSSH and exists ostensibly to
prevent mis-spelling and other errors from causing security problems.

This behaviour affects compatibility between SUNWssh versions as well as
between all versions and derivatives of OpenSSH which share the per-user
configuration file path "~/.ssh/config" and a solution is badly needed.

PROPOSAL
--------

We note that the OpenSSH team feels free to add new ssh_config(4)
parameters at any time, thus refraining from adding parameters to
ssh_config(4) is not an option.  Silently ignoring unknown parameters is
not an option either since this can cause users to assume that ssh(1)
understood a given parameter when it didn't.  Neither is prompting about
unknown parameters appealing.

Therefore we propose to make ssh(1) support a mechanism by which to
inform it of parameters known to other versions of ssh(1) which can then
be safely ignored by it:

 - Add a new ssh_config(4) ssh configuration parameter called
   'IgnoreIfUnknown' whose value(s) is(are) comma-separated lists of
   configuration parameter names. Multiple values will not be combined so
   users can always override system-wide setting.

   Man page text:

     IgnoreIfUnknown
	   Specifies a comma-separated list of ssh_config(4)
	   parameters which, if unknown to ssh(1) are to be
	   ignored by ssh(1).

	   This parameter is primarily intended to be used in the
	   per-user ssh_config(4) ((~/.ssh/config). While this
	   parameter can also be used in the system wide
	   /etc/ssh/ssh_config it's generaly useless as the
	   capabilities of the ssh(1) client on that host
	   should match that file.


 - Whenever new ssh_config(4) configuration parameters are added in
   micro/patch releases the release notes should document the possibility to
   update /etc/ssh/ssh_config on older systems to add the new parameters
   to the IgnoreIfUnknown lists. However, this decision is on local policy
   since this situation might end up with users thinking they are using a new
   option while they are actually not.

 - Support for IgnoreIfUnknown should be backported to SUNWssh 1.0.x
   (Solaris 9's ssh).

 - Sun will contribute patches to OpenSSH for this new option.

   The OpenSSH team doesn't seem to want to commit to any solution;
   typically they don't like to commit to adding support for any user
   requested features unless patches are included.


REFERENCES
----------

http://bugzilla.mindrot.org/show_bug.cgi?id=866