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Overview

This document is intended to provide you with advice on how to configure the use of X-Windows between an emulator instance (either Tru64 or OpenVMS) and it’s Windows or Linux host.

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For the purposes of this document, the following definitions apply:

TermDescription
Hos
HostThe system on which the emulator runs, and also on which the X11 session is displayed
Gues
GuestThe emulated system, on which the X11 clients run

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Displaying Graphical Applications Over The Network

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A DES should almost certainly be encapsulated in a single window, with or without a frame. This can be combined with XDMCP (the X11 Display Manager Control Protocol), if the Guest supports it.

XDMC
XDMCPXDMCP allows the system on which an X-Server is running (the Host) to send a DES initiation request to the system (“Guest”) on which the user would like to run X-applications locally. The session is almost identical to sitting in front of the display connected to the original Alpha hardware. When a new session has been started, the standardX login screen is presented, and the user must authenticate himself.
NO XDMCP
To be completed

(info) This part will be described later

SeveralWindows

Without XDMCP, each application to be run on the guest system must be started individually. This is can be done from Windows using Putty with X11 tunneling enabled, if the Guest supports SSH. If the guest is running Tru64 V4.x or OpenVMS V7.1, it will not have an ssh-daemon. You have several choices in this case:

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Keep in mind that both rsh and telnet transmit everything, including passwords, in clear text over the network.

 

Security Considerations

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Security Considerations

X11 does not contain any provision for encrypting network traffic. This means you must satisfy one of the following conditions:

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NOTE: be sure to disable any firewall on the virtual network devices

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Host Configuration

The procedure for configuring the host depends completely on whether it is running Windows or Linux.

Linux

To be completed(info) This part will be enhanced/described later

In principle, it should be a relatively simple matter to configure the Linux host, because X11 is currently a standard Linux component. This will change soon, though, as many Linux distributions are evaluating new windowing systems, such as Wayland (RedHat, Fedora) or Mir (Ubuntu), which may not offer X11 compatibility.

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You will need to install an X-Server on the Windows host. There are a variety to choose from. The Free and Open Source Software (FOSS) choices include Xming, VcXsrv, and the X-Server available as a package with Cygwin. There are many commercial packages available, including Hummingbird-Exceed, Reflection-X, X-WIN32 and MKS X-Server.

FOSS X-Servers

The Cygwin, Xming, and VcXsrv servers are all based on the X-Org open-source XServer. Xming and VcXsrv in particular are very similar. Xming actually has two versions, a current version (7.5.0.77) with bug-fixes and new features, for which a donation (suggested amount: GBP 10) is required. Without making a donation, and getting a donor password, you can only download and older version (6.9.0.31) from sourceforge (http://sourceforge.net/projects/xming). VcXsrv, on the other hand, seems to be relatively current, with bug fixes and new functionality.

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VcXsrv

This article will concentrate on using VcXsrv. Much will also apply to Xming, and to a certain extent, to the Cygwin server.

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To configure VcXsrv to use several monitors as distinct screens, add "-screen 0 @1 -screen 1 @2" (for two monitors) to the command line parameters. You can also add the “-xinerama” parameter – it depends if the X client programs are Xineramaaware.

 

Configuring the Guest System

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Configuring the Guest System

Tru64 UNIX V4.X and V5.X

Desktop Environment Session (DES) Configuration

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  • Find the file pointed to by /var/dt/Xservers. It will probably be /usr/dt/config/Xservers.nc. Edit this file, and make sure the line “* Local local@console /usr/bin/X11/X :0” is commented out. This stops the emulated system from trying to start an X-Server on the local hardware.
  • Add an entry for the Windows Host in /etc/hosts.
  • If you want to be able to log in as “root”, add a line to the end of /etc/securettys with the value “<windows-host>:0”, where “<windows-host> is the name you added to /etc/hosts.
  • Make sure there is a symbolic link from /sbin/rc3.d/S95xlogin to /sbin/init.d/xlogin. If not, create it using:

    ln -s /sbin/init.d/xlogin /

    etc

    sbin/rc3.d/S95xlogin

After satisfying the above requirements, you can use VcXsrv to initiate the DES via XDMCP. If you prefer to configure the Guest to start the DES, you must add a line to the “/var/dt/Xservers” file of the form:

<hostname>:0 foreign

where <hostname> is the name the you entered in /etc/hosts for the Host.
This approach may be preferable. If the XDM on Tru64 cannot start the DES, for example because the X-Server is not running on the Host, it will wait patiently until the X-Server becomes ready. When a DES is terminated, Tru64 immediately starts a new one.

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Non-DES Configuration

To be completed(info) This part will be described later


OpenVMS V7.1 and V7.3-2

Depending on the OpenVMS version, various methods and mechanisms may or may not be available.

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  • Core environment: configure at least one interface, routing, and time zone
  • Client components: enable “REXEC and RSH”, “RLOGIN”, and possible “TELNET” and “FTP Client”. On V7.3-2 enable “SSH Client”.
  • Server Components: enable RLOGIN, and on V7.3-2 SSH and XDM.

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The Hosts Database (V7.1 and V7.3-2)

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To add a host/IP-address to the database, enter the following command:

PROMPT> SET HOST "hostname"/ADDRESS=<IP-address>/ALIAS=HOSTNAME

Putting the “hostname” in quotes cases it to be entered in lowercase, assuming you also use lowercase characters, which is a Good Idea. The alias will be all uppercase.

After adding a host, you can ping it from within UCX/TCPIP using the command:

PROMPT> PING hostname

V7.1 reports “...host is alive” upon success. V7.3-2 uses the standard UNIX answer syntax, and sends ICMP packets until interrupted using CTRL-C.

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The add an entry to the database, enter the following command:

PROMPT> ADD PROXY VMS_USER/HOST=remote-host/REMOTE_USER=rem_user

For example, to add a proxy for user “urban” on remote host “windows-privnet” for the VMS user “SYSTEM”, enter the following command:

PROMPT> ADD PROXY SYSTEM/HOST=”win-privnet”/REMOTE_USER=”urban”

The quote-characters are important. Please note that VMS will convert all non-quoted characters in commands to uppercase. A proxy entry for the remote user “URBAN” will not match the remote user “urban”.

After you have create such a proxy entry, you can test it from a Linux or Windows system with the command:

# rsh -l system vms-hostname directory

which should display a directory listing of SYSTEM’s login directory.

On Windows, you will need the “rsh_vista.zip” utility (see links below).

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Remote Execution Using RSH

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The entire field should look as follows:

“C:\Program Files\Rsh\rsh.exe” -l VMS_USER vms-hostname
“vms command line”

You should also change the value in the “Run” field from “Normal window” to “Minimized”, which avoids having the CMD-window pop up when the icon is executed.

On the VMS guest, you will probably need to write a small DCL command procedure in order to set up the remote display before starting a DECwindows program. For example, to start a DES, the following DCL procedure can be used:

$ SET DISPLAY/CREATE/NODE=<guest−system−name>/TRANSPORT=TCPIP
$ MC SYS$SYSTEM:DECW$STARTLOGIN
$LABEL:
$ WAIT 2 3 : 5 9 : 5 9
$ GOTO LABEL

This works on V7.1 and V7.3-2. If you only wish to start a single application, such as a DECterm, you can substitute “DECW$TERMINAL” for “DECW$STARTLOGIN” above.

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OpenVMS V7.1

The standard UCX version on VMS V7.1 is 4.1, which does not support XDMCP. You can use the above procedure to start the DES.

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V7.3-2, with the default TCPIP services version 5.4, supports XDMCP. In order to use it, you will need to configure XDM. Please note that I was unable to get XDMCP to work without disabling access control in VcXsrv (adding “-ac” to command line parameters).
To configure VMS V7.3-2 to respond to XDMCP requests, begin by entering the following commands (“$” is the DCL prompt):

$ SET DEF SYS$SPECIFIC:[TCPIP$XDM]
$ COPY XSERVERS.TEMPLATE XSERVERS.TXT
$ COPY XDM_KEYS.TEMPLATE XDM_KEYS.TXT
$ COPY XDM_CONFIG.TEMPLATE XDM_CONFIG.TXT
$ COPY XACCESS.TEMPLATE XACCESS.TXT

Next, edit XACCESS.TXT and add the IP-address of the Host at the bottom.
Next, edit XSERVERS.TXT and comment out any lines at the bottom that would start a remote X session, for example “rufus.compaq.com:0 foreign”.
Finally, restart the XDM service using the following commands:

$ @SYS$MANAGER:TCPIP$XDM_SHUTDOWN.COM
$ @SYS$MANAGER:TCPIP$XDM_STARTUP.COM

You might be tempted to add a line to XSERVERS.TXT to have the VMS system automatically start the DES, however I was unable to get this to work reliably.

 

Appendix

All ftp.stromasys.com links below must be accessed using the “Software” account.

 

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