X refusing remote connections. - X

This is a discussion on X refusing remote connections. - X ; I have an installation of Fedora Core 2 which is refusing remote X sessions. Even after setting "xhost +" on my local machine and setting the DISPLAY variable on the remote computer, I still get: Error: Cannot open display It ...

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  1. X refusing remote connections.

    I have an installation of Fedora Core 2 which is refusing remote X
    sessions. Even after setting "xhost +" on my local machine and
    setting the DISPLAY variable on the remote computer, I still get:

    Error: Cannot open display


    It may be a coincidence, but this seems to have started with the
    change to X.org. Any suggestions would be welcome

    Thanks
    James Hinchey

  2. Re: X refusing remote connections.

    James Hinchey wrote:
    > I have an installation of Fedora Core 2 which is refusing remote X
    > sessions. Even after setting "xhost +" on my local machine and
    > setting the DISPLAY variable on the remote computer, I still get:
    >
    > Error: Cannot open display
    >
    >
    > It may be a coincidence, but this seems to have started with the
    > change to X.org. Any suggestions would be welcome


    It's just coincident that the change of security and change over to xorg
    happened on the same time. Sorry I don't use FC2, so I can't help you with
    that, but you could try to check out the FC1/RH9 XFree86 setup to see the
    difference in the setup of security.


    //Aho

  3. Re: X refusing remote connections.

    On Tue, 26 Oct 2004 16:54:25 +0200, J.O. Aho wrote:
    > James Hinchey wrote:
    >> I have an installation of Fedora Core 2 which is refusing remote X
    >> sessions. Even after setting "xhost +" on my local machine and
    >> setting the DISPLAY variable on the remote computer, I still get:
    >>
    >> Error: Cannot open display
    >>
    >>
    >> It may be a coincidence, but this seems to have started with the
    >> change to X.org. Any suggestions would be welcome

    >
    > It's just coincident that the change of security and change over to xorg
    > happened on the same time. Sorry I don't use FC2, so I can't help you with
    > that, but you could try to check out the FC1/RH9 XFree86 setup to see the
    > difference in the setup of security.


    These days it might be good practice to avoid the totally wide open "xhost
    +"? It is really easy to set up ssh X tunneling. All it takes is setting
    an X tunneling configuration parameter in each ssh(d) conf file. Works
    great! It transparently tunnels the X traffic back to the user machine.

    --
    Juhan Leemet
    Logicognosis, Inc.


  4. Re: X refusing remote connections.

    I agree completely, but our system administrators refuse to set up
    sshd. For some reason I can't comprehend they seem to think that ssh
    is a security problem, but running rsh or telnet isn't. Ordinarily, I
    would not use "xhost +", but rather use xhost with the specific remote
    system name, but that doesn't work either so I tried the more general
    approach.


    Juhan Leemet wrote in message news:...
    > On Tue, 26 Oct 2004 16:54:25 +0200, J.O. Aho wrote:
    > > James Hinchey wrote:
    > >> I have an installation of Fedora Core 2 which is refusing remote X
    > >> sessions. Even after setting "xhost +" on my local machine and
    > >> setting the DISPLAY variable on the remote computer, I still get:
    > >>
    > >> Error: Cannot open display
    > >>
    > >>
    > >> It may be a coincidence, but this seems to have started with the
    > >> change to X.org. Any suggestions would be welcome

    > >
    > > It's just coincident that the change of security and change over to xorg
    > > happened on the same time. Sorry I don't use FC2, so I can't help you with
    > > that, but you could try to check out the FC1/RH9 XFree86 setup to see the
    > > difference in the setup of security.

    >
    > These days it might be good practice to avoid the totally wide open "xhost
    > +"? It is really easy to set up ssh X tunneling. All it takes is setting
    > an X tunneling configuration parameter in each ssh(d) conf file. Works
    > great! It transparently tunnels the X traffic back to the user machine.


  5. Re: X refusing remote connections.

    James Hinchey wrote:

    > I agree completely, but our system administrators refuse to set up
    > sshd. For some reason I can't comprehend they seem to think that ssh
    > is a security problem, but running rsh or telnet isn't.


    Wow, I am speechless- I haven't seen such clueless admins. Anyway xhost+ is
    a security risk, you should consider using xauth. Here is a mini howto:

    http://www.xs4all.nl/~zweije/xauth.html

    Charles


  6. Re: X refusing remote connections.

    Another thing to check is your xdm (or gdm or kdm - whichever you use)
    config file (somewhere in /etc/ - depending on distro)

    Modern distro's default *dm config files tend to start X with the
    "-nolistentcp" option
    (that's because nowadays majority of users eiter don't run remote X apps or
    use ssh tunneling - with ssh tunneling X calls are done locally by sshd - so
    server does not need to listen to remote connection).

    If this is the case, and you don't have write perms to you xdm config file,
    login at a text-mode linux console (CTRL+ALT+F1), and start a personal X
    server manually:

    ~ $ X :1 &
    This will start a new X instance on the next available vc - will also go to
    graphics mode.
    Go back to your console (CTRL+ALT+F1), and make sure you find out how to
    switch to your new X & back. Usually X vc's start from F7, which is already
    taken by XDM. Your new X would probably be in either CTRL+ALT+F8 or F9 (some
    distros use F8 vc for logging, some don't).

    Now you need to start some X apps and a WM
    ~ $ export DISPLAY=:1
    ~ $ xterm &
    Switch back to your X, and you should see the new xterm. Use it to start
    your favorite window-manager (wmaker, twm, etc. for using Gnome/KDE the
    typical command names are startkde/startgnome/kde-session/gnome-session).
    Also use it to do xhost + .


    Note: Always make sure to set DISPLAY to the number of your new server (:1
    in this example) before starting an X app. Another option is adding -display
    :1 to the application's command-line. e.g.

    mylogin@localhost ~$ xhost +
    mylogin@localhost ~$ ssh remotehost
    Password:
    Welcome to RemoteHost
    you have 1 new mail message
    mylogin@remotehost ~$ xterm -display localhost:1 &

    (note: this example uses direct X protocol - not ssh tunneling. Whatever you
    type in the newly open xterm will pass plain on the network)


    "J.O. Aho" wrote in message
    news:2u76hvF26bfo2U1@uni-berlin.de...
    > James Hinchey wrote:
    > > I have an installation of Fedora Core 2 which is refusing remote X
    > > sessions. Even after setting "xhost +" on my local machine and
    > > setting the DISPLAY variable on the remote computer, I still get:
    > >
    > > Error: Cannot open display
    > >
    > >
    > > It may be a coincidence, but this seems to have started with the
    > > change to X.org. Any suggestions would be welcome

    >
    > It's just coincident that the change of security and change over to xorg
    > happened on the same time. Sorry I don't use FC2, so I can't help you with
    > that, but you could try to check out the FC1/RH9 XFree86 setup to see the
    > difference in the setup of security.
    >
    >
    > //Aho




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