ssh protocol 2,1

[Wayne Pinette]

The reason is is because aix version 4.3 stock out of the box is ssh
version 1.  That means both client and server are both ssh 1.  old
versions of aix
are not the only culprits.  Default installations try to be as
"friendly" as possible so others on what ever network you install on
will work.  Being friendly
sometimes means not being entirely secure.  For example, the default
port for ssh is also 22.  Well guess what, every linxu box I have that
has access
to the outside world via ssh does not use the default port, mainly
because I don't need to see the endless spam on my security reports. 
Again, is this
right? or friendly?  I guess in the end, if you really are a sys-admin
being paid to worry about security, then you should know there does
exist ssh 1/2
and to make sure your systems are listening and using protocols your
enterprise deem appropriate.

That's my 2 cents worth.

Wayner


>>> bjt at aa.usno.navy.mil 06/20/06 10:26 am >>>
Mike Burger wrote:
> On Tue, 20 Jun 2006, Bill Tangren wrote:
> 
>> I have a question regarding ssh on RHEL ES4. The man pages indicates

>> that Protocol 2,1 is enabled by default. Could someone explain the 
>> logic of this to me? I thought Protocol 1 had a security flaw.
> 
> 
> That would cause SSHD to require protocol 2, first, then fall back to

> protocol 1 if the client isn't protocol 2 capable.
> 
> If you want to restrict sshd to just protocol 2, remove the ",1".
> -- 
> Mike Burger
> http://www.bubbanfriends.org 
> 

 From the man page for sshd_config:
**********
Protocol
Specifies the protocol versions ssh supports.  The possible values are
"1" and 
"2".  Multiple versions must be comma-separated.  The default is
"2,1".  Note 
that the order of the protocol list does not indicate preference,
because the 
client selects among multiple protocol versions offered by the server.

Specifying "2,1" is identical to "1,2".
**********

This doesn't actually answer my question. If someone *wanted* to
exploit the 
Protocol 1 vulnerability, wouldn't that be easy? [It is a simple
protocol choice 
in Putty, for example.]

There must be a reason for allowing this vulnerability by default. I'd
like to 
know what that reason is.

Thanks for answering, though.

Bill


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