I’m running ubuntu 8.04 and had a problem tunneling the X display from a solaris box to my local ubuntu test server.
when executing this command in my bash script:
DISPLAY=localhost:0
export DISPLAY
xhost +
i would get the following message
xhost: unable to open display “localhost:0″
The problem being the by default ubuntu restricts tcp listening with the following configuration default in:
/etc/gdm/gdm.conf
# If true this will basically append -nolisten tcp to every X command line, a
# good default to have (why is this a "negative" setting? because if it is
# false, you could still not allow it by setting command line of any particular
# server). It's probably better to ship with this on since most users will not
# need this and it's more of a security risk then anything else.
# Note: Anytime we find a -query or -indirect on the command line we do not add
# a "-nolisten tcp", as then the query just wouldn't work, so this setting only
# affects truly attached sessions.
DisallowTCP=true
To fix the error message you can cgange the config option to:
DisallowTCP=false
