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RE: telnet vs ssh on Core equipment , looking for reasons why ?

  • From: alex
  • Date: Tue Jul 31 17:00:52 2001

> > > 
> > > 2) Your vendor's ssh authentication creates a secure connection, and
> > >    transfers the password securely, only to then send the password,
> > >    unencrypted, to an authentication server for verification, making
> > >    ssh moot.
> > 
> > Establish reasonable path for trust propagation and you have solved the
> > problem.
> 
> Except, of course, if I had a reasonable path for trust propigation,
> I would have a trusted path for telnet logins. ;-)
> 
> Any compromise on a clear-text telnet password is going to be viable
> against any other clear-text password transmission.  Even restricting
> logins to certain host ranges only pushes security to those networks.
> If you're going to sniff my backbone passwords, the networks that are
> wrapped in are presumably compromised already.

Not correct. You can always put your authentication server into the trusted
zone. The question is how to transfer information to the authentication
servers from the equipment security. It is a very different proposition from
being able to establish trusted path to the servers from everywhere, which
is what you want for secure telnet.

Alex

> 
> Network security is a beast.  There's no sure method.  Of course,
> the compromises get progressively more unlikely as time goes on
> (including keyboard sniffing and signal analysis.)  So the question
> becomes, what is secure enough?  If you're only using telnet, with
> clear passwords, restricted to a certain range (which, by the way,
> despite a recent post to nanog, we are doing; I'd like to say we
> left that router open so folks could read my poetry, but the truth
> is, we were morons and missed it) you're secure as long as your
> backbone links and backend aren't being sniffed.  Physically tapping
> fiber isn't terribly easy for the average hacker, and careful routing 
> protocol selection and implementation should keep you from external
> intrusion.  So really, your back-end that's the most likely way
> in.
> 
> So... does anybody know how long it takes to hack an ssh key given
> identity and identity.pub?  Because, if I have your machine, I have
> these... it's just a matter of unlocking your passphrase.  (And not
> even that, if you're running ssh-agent and I can get to that...)
> 
> -- 
> Dave Israel
> Senior Manager, IP Backbone
> Intermedia Business Internet
> 
> 





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