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Thread: ssh error "X11 forwarding request failed on channel"

  1. #1
    Join Date
    Oct 2012
    Beans
    21

    Unhappy ssh error "X11 forwarding request failed on channel"

    I am having real problems getting GUI programs to run on a remote 'client' computer after logging into a server. Both client and server are running ubuntu 12.04.

    The client is a 32 bit netbook and the server a 64 bit laptop.

    After trying everything, I eventually simply tried ssh logging into the server computer from a terminal IN the server computer itself. I STILL get the "X11 forwarding request failed on channel" and "Error: Can't open display:" when trying to run a GUI like xclock!

    I have in my sshd_config file:

    X11Forwarding yes
    X11DisplayOffset 10
    PrintMotd no
    PrintLastLog yes
    TCPKeepAlive yes
    PermitRootLogin no
    AllowTcpForwarding yes
    X11UseLocalhost yes
    AddressFamily inet

    and in my ssh_config file
    # ForwardAgent no
    ForwardX11 yes
    # X11DisplayOffset 10
    ForwardX11Trusted yes
    XAuthLocation /usr/bin/xauth

    I'm logging in either using ssh -X -v user@ipaddress or ssh -Y -v user@ipaddress.

    I cant get the X11 to forward.

    I have tried everything in these wiki's:

    https://help.ubuntu.com/community/SS...ing#Forwarding
    https://wiki.archlinux.org/index.php/Ssh#X11_Forwarding

    I'm kind of new at setting up ssh, so what am I doing wrong?

  2. #2
    Join Date
    Jun 2006
    Location
    Houston, TX
    Beans
    1,302
    Distro
    Ubuntu 6.06

    Re: ssh error "X11 forwarding request failed on channel"

    I do this often, and I have never had to configure anything from within X to make it work.

    So, start with the basics. Is X client installed on your server? How was it installed?

    Is there any firewall or filtering between you?

    Are you doing anything with sudo? (Sudo can brake pipes...)

  3. #3
    Join Date
    Oct 2012
    Beans
    21

    Re: ssh error "X11 forwarding request failed on channel"

    Thanks for helping.

    So I don't know if X client is installed. Could you explain this to me?

    The only things I have installed in this regard (beyond what comes packaged with a standard Ubuntu 12.0.4 install) are openssh-server.

    I have the same issue whether ufw on the server is switched off or on. When ufw is on I have set up a rule to allow communication on channel 22.

    But even with ufw switched off on both client and server machines I have the same problem.

    I have done nothing with sudo other than install the openssh-server.

    Port 22 is open on both machines, if it wasn't I'm guessing I wouldn't be able to log in via ssh at all (which I can, just no GUI/X11 forwarding).

  4. #4
    Join Date
    Nov 2008
    Location
    Metro Boston
    Beans
    12,505
    Distro
    Kubuntu 14.04 Trusty Tahr

    Re: ssh error "X11 forwarding request failed on channel"

    Sounds like the server doesn't have the X infrastructure installed which is standard for Ubuntu Server. See if running "sudo apt-get install xorg" on the server solves the problem.
    If you ask for help, do not abandon your request. Please have the courtesy to check for responses and thank the people who helped you.

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  5. #5
    Join Date
    Oct 2012
    Beans
    21

    Re: ssh error "X11 forwarding request failed on channel"

    I think that was it. I already had that installed, but just reinstalled it, and that seems to have dome the trick.

    Thanks.

  6. #6
    Join Date
    Jun 2006
    Location
    Houston, TX
    Beans
    1,302
    Distro
    Ubuntu 6.06

    Re: ssh error "X11 forwarding request failed on channel"

    I actually install a minimum X server with "apt-get install synaptic" or "apt-get install system-config-printer" since it will install the bare minimum to make those X apps run. But it does not install all of gnome, or nautlius, so it may not fit your needs. If you install the entire desktop, make sure you "apt-get purge lightdm" to keep the server in text only mode.

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