Full Disclosure mailing list archives

Re: Re: Re: open telnet port


From: ktabic <lists () ktabic co uk>
Date: Thu, 09 Sep 2004 16:37:28 +0000

On Thu, 2004-09-09 at 09:41 -0400, Andrew Haninger wrote:
How about, as a service to enable as you are updating SSH remotely from
the other side of the country to fix the most recent problem security
problem and need a backup system to get into the server in the event
that something goes wrong?
Maybe it would work as well, to start a ssh daemon on a high port,
login on that high port, update the current sshd, start it up on port
22, logout of the high port, login on port 22, and kill the high-port
sshd.

So,

[foo () box com ~] sshd -p 6000
[bar () xob com ~] ssh foo () box com -p 6000
[foo () box com ~] [kill sshd running on port 22]
[foo () box com ~] [make and install new sshd]
[foo () box com ~] sshd
[bar () xob com ~] ssh foo () box com
[kill sshd running on port 6000]

This would nearly eliminate any danger due to your insecure version of
sshd since it would be running on a non-standard port for a brief
period of time, and you would not be passing any passwords in the
clear.

So the solution to not run a backup telnet server for updating SSH is to
run a second, known insecure version of sshd on a different port,
presuming of course, that you are allowed to run said sshd on said high
port in the first place.
Which results in something that sounds a bit like security by obscurity,
which is bad. You end up presuming that potential attacker cannot do his
thing because you are using ssh on an oddball port.
Oh, and not everyone is root for all parts of the network they may be
administrating.

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