Install Tiger VNC on Redhat 6

If you need to install VNC on RedHat 6, usually you are advised to do a yum install. Most often you will not have a configured yum repository in order to use the command "yum install", and it can take some time to make a local one for yourself.

Lucky me, when I had to install a package in RHEL 6.3 and yum command was not useful, I found out that the packages I need were actually much closer to me than I thought - in the Packages directory of the installation media.
Just connect your RHEL CD. I was using vSphere client to run the VM and when I connected my .iso it was automatically recognized by the RHEL and on the Desktop I got a folder with the date of this disk.
In which I found /Packages and there was my tiger vnc rpm.
A double-click over it and it was installed right away.
Nice and easy, when you have the install media.

Linux host that pings itself resoves to 127.0.0.1

I had a RedHat linux machine which, when pinging itself, would resolve to 127.0.0.1 in the terminal output of the ping command.

This was caused by a wrong configuration in the /etc/hosts file:

127.0.0.1  MachineDNSName localhost.localdomain localhost
::1            localhost6.localdomain6  localhost6

I removed the MachineDNSName entry leaving it to:

127.0.0.1     localhost.localdomain localhost
::1                localhost6.localdomain6  localhost6

Now the pinging the machine from itself started to return its real external IP instead of 127.0.0.1

My example does not show how a host file should be configured. This only shows that an additional entry was resulting with network issues in specific cases (not all the time).
So in case of issues with wrong resolving of machine DNS name, look at your host file for possible issues.

Execute command on remote unix machine via JMeter

To enable this functionality, go to https://github.com/yciabaud/jmeter-ssh-sampler/releases  and download:
ApacheJMeter_ssh-1.1.0.jar
and
jsch-0.1.51.jar

Place the first in your JMeter install folder /lib/ext directory, and the second in /lib.
Restart JMeter, if already open.

Add sampler SSH Command.

VNC server does not respond to ALT+Shift+R sent to Eclipse

Problem: Linux RedHat (RHEL) 5.5 accessed via VNC, open Eclipse IDE. I need to use keybinding Alt+Shift+R which should invoke a renaming operation. Instead, it just opens the "Run" menu.

An option needs to be passed to the vnc server.
In /etc/sysconfig/vncservers   find

   VNCSERVERS="1:user"
   VNCSERVERARGS[1]="-geometry 1024x768 " 

Add +kb

VNCSERVERARGS[1]="-geometry 1024x768 +kb " 

and restart VNC server

+kb is used to enable the X Keyboard Extension 

More options HERE. 

I also had to first find out which VNC server RHEL 5.5. was using because that was not in the docs, or at least I could not find it.
To find out the vendor, grep the vnc process, in my case it returned a list with Xvnc process.
Then do "man Xvnc" where at the botton you see RealVNC.
From here you can go on searching for details about this VNC server once that you know who the vendor is.

Slave no longer connects to your Jenkins master - slave-agent.jnlp: 403 Forbidden

Recently I messed up with Jenkins security configuration causing my slave machines to 
no longer connect to the master with the following exception logged:
Failing to obtain http://MY_JENKINS/computer/MY_SLAVE_NAME/slave-agent.jnlp
java.io.IOException: Failed to load http://MY_JENKINS/computer/MY_SLAVE_NAME/
slave-agent.jnlp: 403 Forbidden
 at hudson.remoting.Launcher.parseJnlpArguments(Launcher.java:275)
 at hudson.remoting.Launcher.run(Launcher.java:219)
 at hudson.remoting.Launcher.main(Launcher.java:192)
Waiting 10 seconds before retry

 

Check your security configuration settings in Manage Jenkins->Configure global 

security and verify that for Anonymous user you have allowed to connect to slave.

Jenkins slave's configuration is not recognized? Try restarting the slave.

I had to reconfigure a Jenkins slave, just a change of the Java version. This caused Jenkins master to not recognize the changed Java on the remote end (the slave) and my build had failures thinking that the Java was still the old version.
This you can see in the node's System information link when you click on the node, this is what currently Jenkins thinks is on the remote end, and this may be wrong.

Solution was to simply restart the slave so that Jenkins can pick up the changes in the environment

Java is not found on your Linux ? It might be the symlinks in /usr/bin that cause this...

It may happen that you have installed Java on your Linux system but it is not recognized as installed and existing.
Check out in /usr/bin directory these symbolic links:
/usr/bin/java
/usr/bin/javaw
They should be pointing to your Java installation folder's and the executables there. For example:

$ ll /usr/bin/java*
  java -> /etc/alternatives/java
  javaws -> /usr/java/latest/bin/javaws

In this case, the first symbolic link is not updated to the latest or default Java bin folder and this may be causing issues.
Change it to point to:
/usr/java/latest/bin/java

and the final result should be:

$ ll /usr/bin/java*
  java -> /usr/java/latest/bin/java
  javaws -> /usr/java/latest/bin/javaws

In my particular case, I wasn't able to find java on my remote Linux machine via SSH connection through PuTTY and adjusting the symlinks in /usr/bin fixed my problem.