如何将X11转发到运行在远程linux主机上的虚拟机？

Question

I am running a virtual machine on a remote linux host:

my machine -> linux host -> virtual machine running on linux host

I have X11 forwarding enabled on the linux host, and on the virtual machine. I am trying to run JVisualVM on the virtual machine on my own machine launched using the ssh command (with ssh -X).

The ssh command I'm using is:

ssh -X -t root@linux_host -L 29998:localhost:29999 ssh -X -t -i /root/.ssh/my_key user@virtual_machine -L 29999:localhost:9999

Once I'm connected I set the display variable with:

DISPLAY=<my machine's ip address>:0.0

Then I run JVisualVM with this, expecting the window to open on my own machine:

/usr/java/jdk1.7.0_95/bin/jvisualvm -cp:a /opt/jboss/bin/client/jboss-cli-client.jar --jdkhome /usr/java/jdk1.7.0_95/

But I either get an error that the display is not set, or JVisual exits after a few seconds with an error code of 2.

Answer 1

Since you're using ssh -X you're apparently expecting to use secure X forwarding with ssh. In this case, ssh sould set the DISPLAY variable for you and your should NOT override it by setting DISPLAY manually. If DISPLAY is not being set by ssh, that means that your ssh server setup has X forwarding disabled (for whatever reason), and you should fix that if at all possible.

If you don't want to (or can't) use ssh X forwarding, you can use a direct connection (by setting DISPLAY as you are doing), but you ALSO need to open up the X server on your machine to remote connections. You do this with xhost on the local machine:

xhost <linux host address>

Note however, that this opens up your local machine to EVERYONE with acces to that linux host, or who can spoof that host address (which means basically everyone everywhere, unless you and the linux machine are inside a firewall), so this is NOT a good idea.

Answer 2

Try adding

X11UseLocalHost no

to

/etc/ssh/sshd_config