Note: Private Access Channel is now available in Oracle Analytics and is recommended by Oracle for new connections to private data sources. For more information on the feature and the data sources it supports refer to:
    Connect to Private Data Sources Through a Private Access Channel
    Supported Data Sources
    A-Team Chronicles Private Access Channel Series

Validated on January 20, 2021 for OAC 5.9

Introduction

This post describes preparing an X11 graphical display system on a Linux 7 compute instance running on Oracle Cloud Infrastructure (OCI). A graphical interface is the default method of using the Oracle Analytics Cloud (OAC) Remote Data Gateway (RDG) installer. This post is also useful for preparing the 1.5 version of Remote Data Connector.

X11 is the simplest graphical display system to provision in a compute instance. Other options include installing a VNC server or a full desktop environment such as GNOME or KDE. 

It also describes configuring an X11 server running on a MAC-OS or Windows client to display a graphical user interface (GUI). 

This post is not intended for those who currently have a Linux environment with a Graphical Display system available for RDG. 

Validations

January 20, 2021 for OAC 5.9

July 22, 2020 for OAC 5.7

May 19, 2020 for OAC 5.6

March 26, 2020 for RDG 105.5

October 15, 2019 for RDG 105.4

June 28, 2019 for RDG 105.3

Topics

Before you Begin

Preparing the X11 Graphical Display System

Preparing the X11 Server

Validating the Graphical User Interface

Preparing Ports for RDC and RDG

 Before you Begin

In this post, the term "instance" refers to the Linux compute instance hosting a RDG agent.

Prerequisites

Preparing the graphical user interface for RDG requires the following:

The IP address or host name of the compute instance.

The SSH private key associated with the instance's public key. 

A SSH utility with X11 tunneling capability to access the instance.

Administration privileges on a MAC-OS or Windows client.

SSH Tunneling

Follow the steps in Preparing SSH Tunneling for Oracle Analytics Cloud Remote Data Gateway in a Private Subnet to configure your SSH client to access the RDG host publicly or privately via a bastion host.

 Preparing the X11 Graphical Display System

This section describes configuring an X11 graphical display system for the RDG Linux installer. It assumes the SSH client config file has an entry named RDG-HOST.

Backup the SSH Daemon Configuration File

​ssh RDG-HOST sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.orig

Modify the SSH Daemon Configuration File

Set the X11UseLocalHost parameter for correct creation of the DISPLAY environment variable. Edit the sshd_config file, uncomment the X11UseLocalHost parameter and change the value from yes to no.

Using a Local Editor

Copy the configuration file down to your client, edit it using a local editor e.g. Notepad, TextEdit and copy the file back to the server.

Establish ownership of the file

ssh RDG-HOST touch sshd_config

Copy the file owned by root to the opc home directory.

ssh RDG-HOST sudo cp /etc/ssh/sshd_config /home/opc

Copy the file to your client's home directory (~)

scp  RDG-HOST:sshd_config ~

Edit the file and change the parameter noted above.

Copy the file back to the opc home directory.

scp  ~/sshd_config RDG-HOST:/home/opc

Copy the file back to original location owned by root.

ssh RDG-HOST sudo cp /home/opc/sshd_config /etc/ssh

Using the Linux vi Editor

SSH Into the Linux Instance

​ssh RDG-HOST

Edit the ssh_config File

sudo vi /etc/ssh/sshd_config

Save the file and exit the vi editor.

Exit the SSH Session

exit

Restart the SSH Daemon

ssh RDG-HOST sudo systemctl restart sshd

Set up X11 Authorization

This is accomplished by installing the xauth application.

ssh RDG-HOST sudo yum -y install xauth

Install the X11 Terminal Emulator

The xterm application may be used to open an X11 terminal on a user's client machine. This post uses it to validate the graphical user interface.

ssh RDG-HOST sudo yum -y install xterm

Install the X11 Test and Extension Library

This library is required for the RDG installer.

ssh RDG-HOST sudo yum -y install libXtst.x86_64

 Preparing the X11 Server

An X11 server running on a client machine is required to display the RDG installer graphical user interface.

Download and Install X11 Server Software

Popular software for MAC-OS is XQuartz at https://www.xquartz.org. Popular software for Windows is Xming at https://sourceforge.net/projects/xming/.

This post uses MAC-OS and XQuartz.

Download the XQuartz .dmg file and install it using the default values.

Download and Install SSH Software

Also required is an SSH client that supports X11 tunneling. For MAC-OS the terminal application is sufficient. For Windows, PuTTY is the most widely used: https://www.putty.org

This post uses MAC-OS and the terminal application.

 Validating the X11 Configuration

The configuration is validated by starting the X11 Server on the MAC-OS. This is done by starting the XQuartz application.

​Start the X11 Server Application.

Use Finder to open the Applications>Utilities folder and double-click XQuartz. An xterm window  opens on the MAC.

Now this terminal session or another remote terminal session can be used to SSH into the Linux instance to run an X11 application. 

SSH into the Linux Server with an X11 Tunnel

Use the SSH utility with the -X option to set up an X11 tunnel session on the Linux instance and run the Linux xterm application.

​​ssh -Y  RDG-HOST xterm &

You may have to wait up to a minute, then a new Xterm window appears on your desktop from the Linux instance validating the configuration.

 Summary

You can now proceed to install and configure an OAC Remote Data Gateway agent on a Linux compute instance.

This post described preparing an X11 graphical display system on a Linux 7 compute instance running on Oracle Cloud Infrastructure and an X11 server running on a MAC-OS client to display an X11 graphical user interface (GUI).

For other posts relating to analytics and data integration visit http://www.ateam-oracle.com/dayne-carley.