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.

Exposure to the Raspberry Pi platform

Earlier this year, we had a project that revolved around the Raspberry Pi / Raspbian platform, which essentially is a low-cost computing architecture, not terribly dissimilar than some of the stuff I saw being engineered for the projects like "one laptop per child".

Of course, when someone first mentioned it, I had not heard of it, and thought they were talking about some kind of edible pie.

Turns out, that these little kits (they tend to be sold as assembly kits) are quite interesting. Sort of like coming back to the old Heathkits; except no soldering is required. Kits tend to come with a mainboard/chip (small form factor), and have pluggable slots for keyboard, HDMI for a screen, 4 USB2.x ports, power, and one ethernet port. At least the one we ordered from Canakit has these, as well as a plastic case that the board can be seated in.

I see there's an entire community around these "disposable computing" devices, ranging from academic projects and use cases to commercial uses.

I should subscribe to some of the periodicals.

Network Attached Storage - Synology

Somehow, through all these years, I managed to somehow evade all things network storage related. Until this week, when I found a couple of NAS devices sitting on a shelf. One was a Buffalo, and I could not get it to boot up due to errors on certain disks.

The other, a Synology, worked perfectly. I had to go to the web, but found a program called Synology Assistant which installed on my Windows 7 laptop. I configured this device to the network, configured RAID 10 on it, set up some shared folders, and configured the SCSI partitions (in SCSI they call them LUNs).  We then loaded a bunch of virtual machines on it, and had an ESXi server use those Virtual Machines. Pretty cool stuff.