XMing – Lightweight X-Server for Windows

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Oracle DBAs working on windows laptops and connecting to unix/linux environments need an Xwindows server. An Xwindows server is the software you need on your laptop in order to run the GUI interfaces for Oracle installation programs on unix. My favorite Xwindows server is Xming, whose home site is located here, and whose binaries are here.

I’ve used the Exceed product before for an Xwindows server, but have always found the software cumbersome and confusing. It contains many more features and utilities than I need and takes up a fair amount of disk space too. Xming is easy to install, tiny in size and just does one thing: Xwindows server. Configuring it to work with putty is simple. Putty seems to be known to just about everybody in IT that ever had to login to a remote machine via telnet or ssh, but I think Xming is probably a bit less famous.

Installing Xming is simple. I accepted all defaults, which lets use run multiple separate programs from your remote host, each in its own window. Xming also provides some choices of automated integration with putty, which I haven’t used.

To get Xming and putty correctly configured to work with SSH, here’s what I had to do in my environment.

After installing Xming, I ran the Xlaunch utility that comes with Xming. Xlaunch controls the manner in which Xming starts. Xlaunch has a wizard interface, and I accepted the defaults, except on this screen.
Xlaunch screen
Here I made sure the “No access control” check box was checked.

On the putty front, I enabled X11 port forwarding for your session. See the below picture on how to do that. In my environment, I don’t have to set the DISPLAY variable at the unix prompt after making the above two settings.
X11 port forwarding in putty.

With the above two settings in place, I can login via ssh using putty from my windows laptop to remote unix sessions and then successfully start Xwindows programs.

file permissions: 10.2.0 on unix, vista issues

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A critical element in computer problem trouble shooting is checking correctness of permissions. Are file permissions correct? What about database permissions? Group membership of operating system ids? And so on. We computer geeks will be doing more of this now that software comes installed with increased attention to security and permissions.

Here are two new wrinkles I ran across today, both involved with installing Oracle.

On a unix host I was trying to enable a unix user id to be able to login and use sqlplus and export/import utilities, but I did not want this id to belong to the dba unix group. I was working on Solaris with Oracle 10.2.0.4.0. However, each time the user invoked sqlplus, “Permission denied” errors resulted. Clearly a permission problem, but I did not want to perform trial and error chmod commands on various files. Metalink yielded an exact match for my problem. Permission Denied Errors for users other than “oracle”, docid 443638.1. Turns out that in Oracle 10.2.0 and higher, the Oracle installers sets file permissions quite restrictively for security reasons. There is a script that one can run to relax permissions. It’s $ORACLE_HOME/install/changePerm.sh.

The other permission issue concerned installing an Oracle client on Vista. (Side note: you have to do Oracle 10.2.0.3 or higher to get Oracle client to work on Vista.) I was using an automated script to install the client and had added to the script some file copy statements to get the correct sqlnet.ora, tnsnames.ora and ldap.ora files on the client machine. Vista didn’t like that since the User Account Control (UAC) feature was turned on. UAC blocks file copy/delete via scripts, and throws up lots of confirmation dialogs if you are manipulating files via GUI tools. But you can disable UAC. My Digital Life and The How To Geek explain how on their blogs. For good measure, I’ll copy and paste what they provided below. Involves updating registry keys.

Disable UAC
C:\Windows\System32\cmd.exe /k %windir%\System32\reg.exe ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 0 /f

Enable UAC
C:\Windows\System32\cmd.exe /k %windir%\System32\reg.exe ADD HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System /v EnableLUA /t REG_DWORD /d 1 /f