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

  • From: Dave Israel
  • Date: Tue Jul 31 14:46:12 2001


[Yeah, I know, we've wandered off topic.  But security is fun to 
talk about.]

On 7/31/2001 at 12:41:23 -0400, alex@yuriev.com said:
> 
> > 
> > 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.

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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