I have a Java application written with Swing that I'm trying to run on a remote Linux server and display on my local machine (running MacOS).
By searching here, I know that this depends on X11, and that I need to enable X11 on both the client and server sides.
On the server side, X11 is installed by examining the /etc/ssh/sshd_config file and confirming that "X11Forwarding" is set to "yes". I also confirmed that xauth is installed and is on the path (in /usr/bin/xauth).
On the client side, I'm invoking ssh with both the -X (capital) and -v options. The -v option causes a bunch of debug lines to be displayed, but none reference X11 in any way. I was looking for something that referenced X11 forwarding, but nothing was displayed (and nothing indicating that it was suppressed either). Also, I checked the client side (MacOS) in the /etc/ssh_config and it has both "ForwardX11" and "ForwardX11Trusted" set to "yes".
Attempting to run the program anyway, I get a "headless" exception and the stack trace does include my application (so I know that I'm invoking the correct program without classpath issues).
This is the exact same error (and same stacktrace) that I get if invoking ssh without the -X option.
I then tried "export DISPLAY=:0.0" and "1.0" and get a different exception ("Can't connect to X11 window server using ':0.0' as the value of the display variable").
I don't know enough to understand if the X-Window server is something that needs to be running on the server or my local Mac.
If it's on the Mac, I don't know (yet) how to do that, but I'll research that. I'm just looking for a pointer in the right direction.
Here is the stack trace:
Exception in thread "main" java.awt.HeadlessException:
No X11 DISPLAY variable was set, but this program performed an operation which requires it.
at java.awt.GraphicsEnvironment.checkHeadless(GraphicsEnvironment.java:204)
at java.awt.Window.<init>(Window.java:536)
at java.awt.Frame.<init>(Frame.java:420)
at java.awt.Frame.<init>(Frame.java:385)
at javax.swing.SwingUtilities$SharedOwnerFrame.<init>(SwingUtilities.java:1758)
at javax.swing.SwingUtilities.getSharedOwnerFrame(SwingUtilities.java:1833)
at javax.swing.JDialog.<init>(JDialog.java:272)
at com.fi.tools.gui.common.BaseGuiDriver.start(BaseGuiDriver.java:35)
at com.fi.tools.gui.CreateWorkflowTask.<init>(CreateWorkflowTask.java:38)
at com.fi.tools.gui.CreateWorkflowTask.<init>(CreateWorkflowTask.java:33)
at com.fi.tools.gui.CreateWorkflowTask.main(CreateWorkflowTask.java:28)
The ssh login:
===> ~ $ ssh -X -v dsmith@app1
OpenSSH_6.2p2, OSSLShim 0.9.8r 8 Dec 2011
debug1: Reading configuration data /etc/ssh_config
debug1: /etc/ssh_config line 20: Applying options for *
debug1: Connecting to app1 [16x.24y.5z.7w] port 22.
debug1: Connection established.
debug1: identity file /Users/dave/.ssh/id_rsa type -1
debug1: identity file /Users/dave/.ssh/id_rsa-cert type -1
debug1: identity file /Users/dave/.ssh/id_dsa type -1
debug1: identity file /Users/dave/.ssh/id_dsa-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.2
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.2p2 Ubuntu-4ubuntu2.2
debug1: match: OpenSSH_7.2p2 Ubuntu-4ubuntu2.2 pat OpenSSH*
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-sha1-etm@openssh.com none
debug1: kex: client->server aes128-ctr hmac-sha1-etm@openssh.com none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<2048<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: RSA ff:3c:2c:17:65:bc:be:c3:ba:c3:27:83:f6:6b:1d:e8
debug1: Host 'app1' is known and matches the RSA host key.
debug1: Found key in /Users/dave/.ssh/known_hosts:4
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Trying private key: /Users/dave/.ssh/id_rsa
debug1: Trying private key: /Users/dave/.ssh/id_dsa
debug1: Next authentication method: password
dsmith@app1's password:
debug1: Authentication succeeded (password).
Authenticated to app1 ([16x.24y.5z.7w]:22).
debug1: channel 0: new [client-session]
debug1: Requesting no-more-sessions@openssh.com
debug1: Entering interactive session.
debug1: client_input_global_request: rtype hostkeys-00@openssh.com want_reply 0
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
Welcome to Ubuntu 16.04.2 LTS (GNU/Linux 4.4.0-62-generic x86_64)
