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Thread: SSH problems

  1. #1
    Join Date
    Sep 2006
    Beans
    109

    SSH problems

    I cannot ssh into an ubuntu 7.10 server I set up last night.

    I am using an ubuntu 7.10 desktop machine to ssh into a 7.10 server. Here is the error message:

    Code:
    @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
    @    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 the RSA host key has just been changed.
    The fingerprint for the RSA key sent by the remote host is [key]
    Please contact your system administrator.
    Add correct host key in /home/baka/.ssh/known_hosts to get rid of this message.
    Offending key in /home/baka/.ssh/known_hosts:3 RSA host key for [IP & Port] has changed and you have requested strict checking.
    Host key verification failed.
    I have installed Bastille on my 7.10 desktop. I cannot tell if the problem comes from Bastille or the SSH configuration on my server.

  2. #2
    Join Date
    Aug 2006
    Beans
    841

    Re: SSH problems

    there was a vulnerability in ssh key generation, and you must have been forced to regenerate keys....

    deleting ~/.ssh/known_hosts will fix you. unless you are being attacked with a man in the middle kind of attack. make sure you are in a trusted zone when you accept the new key

    EDIT,

    just open the known_hosts file and delete the third line, so that you dont have to accept keys for all known hosts again

  3. #3
    Join Date
    Feb 2008
    Location
    US
    Beans
    2,782
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: SSH problems

    did you have an old ssh server on the machine and then reinstall. If so that just means that your desktop machine has stored the old ssh key and it notices it changed and is letting you know. This is to make sure no one is intercepting your ssh traffic. If you know that this isnt happening the matter is easily resolved by editing /home/baka/.ssh/known_hosts and removing the third line.
    Code:
    gedit /home/baka/.ssh/known_hosts
    Desktop: Q6600 OC: 343 x 9, 4 GB RAM, 8600 GTS Twinview (22",17"), 1.5 TB RAID 5
    Laptop: Lenovo T61 T7300 @ 2 GHz, 2GB RAM, Nvidia 140M Quadro, 160 GB harddrive
    Remember to mark posts as [SOLVED] when your problem is resolved

  4. #4
    Join Date
    Sep 2006
    Beans
    109

    Re: SSH problems

    I think I used the same IP address and port for my previous configuration. I am at work now but I will check it out when I get home. Thanks!

  5. #5
    Join Date
    Sep 2006
    Beans
    109

    Re: SSH problems

    What if i was subject to a man in the middle attack, what would I do?

  6. #6
    Join Date
    Feb 2007
    Beans
    106
    Distro
    Ubuntu 5.10

    Re: SSH problems

    Quote Originally Posted by dreadh3ad View Post
    What if i was subject to a man in the middle attack, what would I do?
    Create an entry in iptables to block that specific mac. Or you could just pull the plug on the server.

  7. #7
    Join Date
    Feb 2008
    Location
    US
    Beans
    2,782
    Distro
    Ubuntu 8.04 Hardy Heron

    Re: SSH problems

    if you are doing this across your local network at your house and you are just using internal IPs it really isnt possible unless the "man in the middle" was your brother or something.
    Desktop: Q6600 OC: 343 x 9, 4 GB RAM, 8600 GTS Twinview (22",17"), 1.5 TB RAID 5
    Laptop: Lenovo T61 T7300 @ 2 GHz, 2GB RAM, Nvidia 140M Quadro, 160 GB harddrive
    Remember to mark posts as [SOLVED] when your problem is resolved

  8. #8
    Join Date
    Jun 2008
    Location
    Calgary, Alberta
    Beans
    1,125
    Distro
    Ubuntu 12.04 Precise Pangolin

    Re: SSH problems

    I imagine it is just a reinstall issue. I had the same thing happen when I changed from wubi to a full install. I found that deleting ~/.ssh/known_hosts (as eldragon suggests) worked best. It will simply write a new file for ssh access and you should be good to go.

  9. #9
    Join Date
    Sep 2006
    Beans
    109

    Re: SSH problems

    Quote Originally Posted by tamoneya View Post
    did you have an old ssh server on the machine and then reinstall. If so that just means that your desktop machine has stored the old ssh key and it notices it changed and is letting you know. This is to make sure no one is intercepting your ssh traffic. If you know that this isnt happening the matter is easily resolved by editing /home/baka/.ssh/known_hosts and removing the third line.
    Code:
    gedit /home/baka/.ssh/known_hosts
    How is it I can open that path yet it remains hidden when using 'ls'?

  10. #10
    Join Date
    May 2008
    Location
    Los Gatos, CA, USA
    Beans
    175
    Distro
    Ubuntu

    Re: SSH problems

    Quote Originally Posted by dreadh3ad View Post
    How is it I can open that path yet it remains hidden when using 'ls'?
    Files starting with a period are hidden... try "ls -a"
    Professional and hobbyist programmer. Current project: Odysi and SydMVC.

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