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SSH Unexpectedly Not Prompting for Password

+1 vote
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I have a question about SSH that I can't seem to figure out. Here is the situation:

4 servers on RHEL 6.3

One server has a local account ("teddy"). SSH key pairs have been set up between this "teddy" account and the other 3 servers on a different local account common to the other 3 servers ("bear"), but not present on the "teddy" server. These 3 servers do not have a "teddy" account.

Now, I am able to ssh without password between the 3 "bear" servers using the "bear" account without a password. This behavior is undesired as it bypasses some key controls.

I figure what must be happening here is that since the 3 "bear" servers have the same public key that points to the "teddy" server, they must be using that fourth server as some type of "witness" to verify the identity of the user making the ssh connection, bypassing the password for the "bear" account. I have disabled AgentForwarding on all 4 servers in question, as well as X11Forwarding. This has not helped.

What is going on here and how do I avoid it?

posted May 14, 2013 by anonymous

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4 Answers

0 votes

SSH doesn't work that way. There is not a ability to be a "witness".

SSH keys are independent of the local user account. All that's necessary is for a particular user to have the public key in its authorized keys file and then SSH will use public key authentication vs password based
authentication.

Check out /var/log/secure to see how you are logging in. Look at /home/*/.ssh/authorized_keys to see who has what keys.

answer May 14, 2013 by anonymous
0 votes

As someone else said, ssh doesn't work that way. Question 1: where's your
home directory - it's not NFS mounted, is it? Second, did you do an
ssh-add on teddy, first? Third, are you doing ssh -A?

answer May 14, 2013 by anonymous
0 votes

Well, something is certainly accepting the pubkey so it could be AgentForwarding.

if you echo $SSH_AUTH_SOCK is the variable defined?

and does a process list show ssh-agent running?

Also, check /etc/ssh to see if there's a authorized keys file there.

answer May 14, 2013 by anonymous
0 votes

If I'm understanding correctly, you have the "teddy" key set in "bear's"
authorized_keys file, and you also have "bear" using the same "teddy" key.
Use the -v flag when doing the ssh to verify what key the client is using;
I think you see that it is using the "teddy" pub key which you placed in
"bear's" .ssh dir.

I'm currently using a key created on a long dead box to connect to the
console of a VPS I have, mostly cause I'm too lasy to create a new one.
Every time I log in it says using pub from "@".

answer May 14, 2013 by anonymous
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