Oracle Linux - renaming your hostname


Here is a quick note on the procedure for renaming the hostname of a server running with Oracle Linux. In this example, I cloned my Virtualbox VM (kirlinc.home) to a new VM with hostname as kirlinb.home
Clone Virtual Machine
==> Use the virtualbox Clone option to Clone an existing VM(kirlinc) to a new VM (kirlinb)
      Provide the new Network Configuration for the copied VM
      Make sure you reinitialize the mac address, so the new VM gets the new address

64bit Guest OS installation error


This kernel requires an X86-64 CPU, but only detected an i686 CPU.
Unable to boot – please use a kernel appropriate for your CPU.


If you are running into this error, it could be due to the invalid Operating System option chosen on the Virtual Machine (VM). Installing 64bit Guest OS is supported on a 32bit Host operating System provided your Host Machine has a 64bit processor and you explicitly choose 64-bit Operating System for that particular VM.
For more information Please see the Virtualbox User Manual...

Configuring port access using Linux Server Firewall


Many of the Linux distributions come with a very powerful system firewall using IPTables. IPTables program can be used to setup rules for enabling/disabling access to various ports on the server.
Here is an example where I cannot access the "DBExpress" application running on machine kirlinc.home with port 8888 from any of my other servers in the network.

Copyright ©2018 Rajkiran Ghanta (