HELP - can't connect to old sshd --SOLVED

Moriah · Last edited by Moriah on Tue Nov 17, 2015 8:07 pm; edited 1 time in total

Since last week's update, I am unable to connect via ssh to a machine that I do not administer:

Tony0945 · Posted: Sat Nov 14, 2015 4:43 pm Post subject:

You have to drop down to the older ssh on your immediate machine, then log in with the old key system. Once you have logged in, update the keys to a method that the newest sshd supports, then you can update both. Search the forum and I believe there was a news item regarding keys.

I don't use keys since they go out of date when either machine reboots. Note also that root logins are no longer allowed. That's why I have masked sshd-7.0 and above.

NeddySeagoon · Posted: Sat Nov 14, 2015 5:03 pm Post subject:

Tony0945,

Gentlenoob · n00b Joined: 10 Apr 2008 Posts: 72

Moriah,

in my case, which looks similar but not completely identical, the following lines in my .ssh/config helped:

Tony0945 · Posted: Sat Nov 14, 2015 6:30 pm Post subject:

freke · Posted: Sat Nov 14, 2015 8:24 pm Post subject:

Hu · Administrator Joined: 06 Mar 2007 Posts: 22835

Moriah · Posted: Sat Nov 14, 2015 8:57 pm Post subject:

My original question was about initial key exchange for a password login
This thread has been hijacked to the issue of stored keys

That's not what I asked about. I cannot login into an old machine using a password. It never even gets as far as asking for the password, because the key exchange method to encrypt my password is not the same at both ends.

Can anybody address *THAT* question?
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toralf · Posted: Sat Nov 14, 2015 9:00 pm Post subject:

So, you didn't find anything here : http://www.openssh.com/legacy.html which helps ?
(took 2 sec to google that - it is the very first entry in the hit list)

NeddySeagoon · Posted: Sat Nov 14, 2015 9:25 pm Post subject:

Moriah,

The password is not exchanged when you use key based login.

Its an encrypted challenge and encrypted response that are exchanged.
The password you enter is used to unlock your private key so that the encrypted response can be sent.

The problem is that the two machines cannot agree on the encryption to be used for the challenge/response phases.
The remote box only offers diffie-hellman-group1-sha1.

Asking what ssh supports for key exchange gets me

Moriah · Posted: Sat Nov 14, 2015 9:34 pm Post subject:

Looks the same as yours:

Tony0945

Moriah · Posted: Sat Nov 14, 2015 10:50 pm Post subject:

I never said it was *deliberate* hijacking, really meant the topic drifted somewhat from my original problem. I see now how it does look like it could be a key problem. I did not give enough detail. :oops:

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The MyWord KJV Bible tool is at http://www.elilabs.com/~myword

Foghorn Leghorn is a Warner Bros. cartoon character.

freke · Posted: Tue Nov 17, 2015 7:49 pm Post subject:

You have any KexAlgorithms set in sshd_config?

ie. I have

Moriah · Posted: Tue Nov 17, 2015 8:07 pm Post subject:

Neddy solved this one for me. I had to specify an option to the ssh client so it would work with what the server had to offer.
_________________
The MyWord KJV Bible tool is at http://www.elilabs.com/~myword

Foghorn Leghorn is a Warner Bros. cartoon character.

NeddySeagoon · Posted: Tue Nov 17, 2015 8:20 pm Post subject:

Moriah,

You can fix it in your ssh_config too, so you don't need the command line option.
Its your ssh client you need to fine tune.

freke suggested sshd_config, which will set the options for your sshd server.

Meanwhile, file a bug with the server operator and get them to update their sshd
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Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

toralf · Posted: Tue Nov 17, 2015 8:21 pm Post subject:

Moriah · Posted: Tue Nov 17, 2015 9:46 pm Post subject:

I added SOLVED to the title of the thread. I guess you didn't look...
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The MyWord KJV Bible tool is at http://www.elilabs.com/~myword

Foghorn Leghorn is a Warner Bros. cartoon character.