Firewalld

People are starting to use this Firewalld.

I needed to get a quick understanding of it, and found this particular link a good starting point:

https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-firewalld-on-centos-7

DNS Resolution

Learned a lot about DNS resolution today, watching a colleague debug and configure this.

Need to look more into this.

AlienVault - Ossim

Downloaded the ISO for this today. I'll be playing around with this to see what it's all about.

KVM Virtualization - Initial Install

The site I chose to use to get guidance on the installation was:

http://www.itzgeek.com/how-tos/linux/centos-how-tos/install-kvm-qemu-on-centos-7-rhel-7.html

Pretty decent site.

After running the installation, I realized I needed to run virt-viewer to get things going, but immediately ran into the following error:

"virt-viewer undefined symbol g_type_check_instance_is_a fundamentally a"

In searching for a fix for this, I found a thread, and one of the suggestions was to try reinstalling virt-manager, by doing "yum reinstall virt-manager".
https://www.centos.org/forums/viewtopic.php?t=4175

After I did this, virt-manager seemed to work just fine and came up.

I then selected my virtual machine, and tried to power it up. It failed during boot with a "no bootable device" error. So, another search provided the fix for this problem, which was to go into device settings and change the image type to raw, from qcow. I guess kvm expects people to load qcow images by default.

https://azitech.wordpress.com/2011/07/23/no-bootable-device-on-kvmqemu/

The next issue I ran into, was again another boot issue. It looks like it tried to boot from DVD, then from ROM (looked like it worked), and then tried to boot from a floppy? That's where I am now (screenshot below).



Finally, I went back and noticed that my ISO image was 0 bytes. So I deleted the VM entirely, re-copied the ISO, and ran the "Install New VM" process again, with the option to do advanced configuration before installing (checkbox) selected.

This time, I did a couple of things that I didn't do before (I had overlooked them before). On the prompt where it says "Automatically detect operating system based on install media", I unchecked that box, selected Linux, and chose Red Hat 6.6. I then went into Boot Options and checked the box for Boot Menu, and unselected both the IDE Disk as well as ISO Image.  When I did this, and clicked the button to kick off the Install.

This time, I got the blue CentOS bootup screen.

UPDATE:
I could never get a new CentOS VM to install / load on this laptop I was using (HP older version with 4Gb RAM). I finally installed KVM on a more powerful Dell Precision T1700 server, and we'll see how it works on this. Actually, there is no X installed on this server, which means that I will need to run the GUI from the HP laptop, but the KVM host itself will be on this more powerful server.

D-Bus

I was reading up on FirewallD (separate post altogether forthcoming), and noticed it was based on D-Bus, which is an interprocess communication mechanism.

I thought I was aware of all of the interprocess communication mechanisms, but this one is more recently developed.

Looks like I have some reading to do in order to get current on this.