playing around with removing algos

[Cristian Ionescu-Idbohrn]

On Mon, 1 May 2017, Cristian Ionescu-Idbohrn wrote:
> 
> Example, 'Macs'.
> 
> On the man page I read:
> 
> "Multiple algorithms must be comma-separated.
> ...
> If the specified value begins with a '-' character, then the
> specified algorithms (including wildcards) will be removed"
> 
> It seems that just one algo name is supported on such a line, example:
> 
> 	Macs -umac-64*
> 
> But this form is not supported:
> 
> 	Macs -umac-64*,-hmac-sha1*
> 
> nor is this:
> 
> 	Macs -umac-64*
> 	Macs -hmac-sha1*
> 
> And I have difficulties in finding _one_ pattern that matches _only_ 
> the above algo families, but nothing else.
> 
> Can you confirm this behaviour?  Can it be improved?

More observations.

After doing one of the above in /etc/ssh/sshd_config:

# sshd -tT | sort | egrep '^macs'
macs umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,
hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,
umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1

umac-64* is gone, but I can still use umac-64 at openssh.com to login:

$ ssh -oMacs=umac-64 at openssh.com localhost

Can you confirm this behaviour?


Cheers,

-- 
Cristian