ssh: impossible to access from outside (RHEL 7)...:(

Latest response

Dear all,

good morning.
I have installed RHEL 7 on my Dell workstation.
I have allowed the ssh service through the firewall, but it is impossible to access to the workstation.
In particular, the behavior of ssh is different according to the other machine which tries to connect from inside the same network:

Machine "1":
the first time it connected via ssh;
shutting down the connection and re-connecting back from Machine "1", it says "Connection timed out" and never connects any more from Machine "1";

Machine "2":
the first time connected via ssh;
shutting down the connection and (immediately) re-connecting back from Machine "2", the following message appears:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
6e:45:f9:a8:af:38:3d:a1:a5:c7:76:1d:02:f8:77:00.
Please contact your system administrator.

and never connects more from Machine "2"....

Please, what can I do?
It is mandatory for me to make these machine dialogue with each other...
Is there something I have to do with iptables, even though I have put as "secure" the ssh service in the firewall?

Thanks in advance and my best regards

Giacomo

Responses

Giacomo,

Do you use dhcp to get a ip-address or have you received an ip-address that was used for another Unix or Linux machine in the past?

This is mostly the cause of the error you get on Machine 2.

Got to the .ssh subdirectory in the home directory of the user that want to create the ssh connection.
edit known_hosts and remove the entries for the ip-address and/or hostname of the laptop.

The machine 1 issue I have not a clue, without any error log entries from /var/log/messages.

Kind regards,

Jan Gerrit Kootstra

Hi.-
Thanks for Your reply and sorry for the delay.
No change in the ip address has ever been made: the ip is static and it was given to the new machine.
Today, I have tried to access, and again the WARNING message.
Then, I deleted the known_host lines in the other machines and tried to access again via ssh.
Now it always asks for the user password, saying
Permission denied, please try again.
(I have double-checked the password with some colleagues of mine, and they have the same issue)....

Which message should I provide You from the /var/log/ folder?
What else can I do?

Many many thanks and my best regards

Herger

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