https://wiki.centos.org/HowTos/Virtualization/VirtualBox/CentOSguest
The trick here is in finding Devices. Devices is actually in the VM window - not the host manager window! If you don't know this, you may find yourself tripping through all of the host menus and submenus trying to find the "Install Guest Additions" prompt.
Obviously you need to have the ISO mounted.
So again:
Copy Guest Additions iso to the VM
Go to the VM window, choose "Optical Drive" and mount that ISO.
Then go to Devices, Insert Guest Manager CD Image
Lastly, choose Install Guest Additions (once CD is loaded) - also from Devices on the VM.
Wednesday, June 22, 2016
Tuesday, June 21, 2016
Installing a KVM Host on CentOS 7
I am using another reference to do this, which can be found below.
http://www.server-world.info/en/note?os=CentOS_7&p=kvm
Ok. After I followed these instructions, I had to locate another site:
http://www.itzgeek.com/how-tos/linux/centos-how-tos/install-kvm-qemu-on-centos-7-rhel-7.html
So basically, step 1 is to install the necessary packages. Using BOTH of these sites, I came up with the following list:
- qemu-kvm = QEMU emulator
- qemu-img = QEMU disk image manager
- virt-install = Command line tool to create virtual machines.
- libvirt = Provides libvirtd daemon that manages virtual machines and controls hypervisor.
- libvirt-install = Provides libvirtd daemon that manages virtual machines and controls hypervisor.
- bridge-utils = creating bridges, et al.
- libvirt-client = provides client side API’s for accessing servers and also provides virsh utility which provides command line tool to manage virtual machines.
- virt-viewer – Graphical console
So I installed these using yum -y (assume yes) ...packages...
Next, step 2, is to create a bridge that will be used to allow the VMs inside the KVM to reach the NIC on the box to communicate with outside networks.
Actually, because I already have a bridge interface (br0), I am going to try to use that rather than creating a bridge.
Next, I need to connect to the KVM host. I don't have X on this machine, so I will need to connect from another CentOS 7 box that does have X installed. On that box, which has X and Gnome Desktop, I installed libvirt, libvirt-client, and virt-viewer.
But - I ran into a problem connecting.
After debugging, I realized the KVM host does not accept inbound SSH connections as root. So I tried to connect as a different user that is in the wheel group, and this did not work either.
I think the answer to that is in this blog here, which involves policy set up.
http://wiki.libvirt.org/page/SSHPolicyKitSetup
This in fact did not work either, so I instead did this:
https://goldmann.pl/blog/2012/12/03/configuring-polkit-in-fedora-18-to-access-virt-manager/
This in fact did not work either, so I instead did this:
https://goldmann.pl/blog/2012/12/03/configuring-polkit-in-fedora-18-to-access-virt-manager/
polkit.addRule(function(action, subject) { if (action.id == "org.libvirt.unix.manage" && subject.local && subject.active && subject.isInGroup("wheel")) { return polkit.Result.YES; } });
But I took the subject.local out, because I was connecting from a remote machine.
next, on the other CentOS 7 device I was connecting to the KVM host from (which is also a CentOS 7 VM on Virtual Box), we ran the following commands so that we wouldn't get repeatedly authenticated.
ssh-keygen (accept defaults)
ssh-copy-id [ kvm host address ]
UPDATE:
I finally got a server with 32 Gb RAM to use as a KVM host. I decided NOT to put XWindows on this host, and use it, truly, just as a host. I set up a virt-manager on another VirtualBox Linux VM, and figured I would use that to interact with the host.
I had a devil of a time getting the darn VMs to install.
Finally, I realized that the secret, was to pass in some extra-args on the command line. I realized this on a web discussion, which I would have liked to have posted here, but unfortunately I could not relocate that discussion. Also, I had to change cdrom to "location". Once I did this, I was able to see standard console output on the install.
#!/usr/bin/bash
virt-install \
-n CentOS7-KVM1 \
--description "KVM1 CentOS7" \
--os-type=Linux \
--os-variant=centOS7.0 \
--ram=2048 \
--vcpus=2 \
--disk path=/home/kvm/images/vDisk0.img,bus=virtio,size=10 \
--graphics none \
--location /var/tmp/CentOS-7-x86_64-Minimal-1511.iso \
--network bridge:virbr0 \
--extra-args "console=tty0 console=ttyS0,115200n8 serial"
next, on the other CentOS 7 device I was connecting to the KVM host from (which is also a CentOS 7 VM on Virtual Box), we ran the following commands so that we wouldn't get repeatedly authenticated.
ssh-keygen (accept defaults)
ssh-copy-id [ kvm host address ]
UPDATE:
I finally got a server with 32 Gb RAM to use as a KVM host. I decided NOT to put XWindows on this host, and use it, truly, just as a host. I set up a virt-manager on another VirtualBox Linux VM, and figured I would use that to interact with the host.
I had a devil of a time getting the darn VMs to install.
Finally, I realized that the secret, was to pass in some extra-args on the command line. I realized this on a web discussion, which I would have liked to have posted here, but unfortunately I could not relocate that discussion. Also, I had to change cdrom to "location". Once I did this, I was able to see standard console output on the install.
#!/usr/bin/bash
virt-install \
-n CentOS7-KVM1 \
--description "KVM1 CentOS7" \
--os-type=Linux \
--os-variant=centOS7.0 \
--ram=2048 \
--vcpus=2 \
--disk path=/home/kvm/images/vDisk0.img,bus=virtio,size=10 \
--graphics none \
--location /var/tmp/CentOS-7-x86_64-Minimal-1511.iso \
--network bridge:virbr0 \
--extra-args "console=tty0 console=ttyS0,115200n8 serial"
Thursday, June 16, 2016
Percona and MariaDB
Downloaded PerconaDB today.
Apparently it is re-packaged MariaDB, which in turn is re-packaged MySQL.
Why Percona? For Clustering.
More later.
Apparently it is re-packaged MariaDB, which in turn is re-packaged MySQL.
Why Percona? For Clustering.
More later.
CentOS7 Minimal Install - No ifconfig or earlier ip commands
On CentOS 7, they deprecate the older ip utilities in favor if iproute2.
There's a blog that discusses how to install the older utilities.
yum install net-tools
The blog also has some other information:
https://www.unixmen.com/ifconfig-command-found-centos-7-minimal-installation-quick-tip-fix/
Wednesday, June 1, 2016
TeamViewer
Someone today was discussing how TeamViewer has an uncanny ability to circumvent firewalls.
Does it punch out? Or other trick(s) are employed?
Need to look more into this.
Does it punch out? Or other trick(s) are employed?
Need to look more into this.
Tuesday, May 31, 2016
How Much Data Does It Take to Stream?
Thinking about using a Chromecast or similar kind of device to stream data?
How much data does this pump through your monthly subscription?
Well, here is an excerpt from the Netflix website, which can be used as a guide.
This can also be reached at the following link (at least, at the time of this posting): https://help.netflix.com/en/node/87
How much data does this pump through your monthly subscription?
Well, here is an excerpt from the Netflix website, which can be used as a guide.
This can also be reached at the following link (at least, at the time of this posting): https://help.netflix.com/en/node/87
How can I control how much data Netflix uses?
Watching movies or TV shows on Netflix uses about 1 GB of data per hour for each stream of standard definition video, and up to 3 GB per hour for each stream of HD video. This can create headaches for Netflix members who have a monthly bandwidth or data cap on their Internet service. Below, you'll find a few ways to reduce the amount of data Netflix uses, without having to resort to drastic measures (like actually watching less Netflix).
Data usage settings only apply to the Netflix profile you are in when you set them, meaning you can have different data usage settings for each profile. If you are concerned about the total amount of data that Netflix uses, make sure to change this setting for each profile.
If you are interested in managing your cellular data usage on individual mobile devices, visit How do I manage mobile data usage on Netflix?
Adjust your data usage settings
Adjusting the data usage settings for your account is the easiest way to reduce the amount of bandwidth used while watching Netflix. There are four data usage settings to choose from. Each estimate below is per stream:- Low (0.3 GB per hour)
- Medium (SD: 0.7 GB per hour)
- High (Best video quality, up to 3 GB per hour for HD and 7 GB per hour for Ultra HD)
- Auto (Adjusts automatically to deliver the highest possible quality, based on your current Internet connection speed)
Data usage settings only apply to the Netflix profile you are in when you set them, meaning you can have different data usage settings for each profile. If you are concerned about the total amount of data that Netflix uses, make sure to change this setting for each profile.
If you are interested in managing your cellular data usage on individual mobile devices, visit How do I manage mobile data usage on Netflix?
Monday, May 16, 2016
Kernel Policy Modules
After installing Lighttpd, we kept getting an error:
Lighttpd doesn't start - selinux
Lighttpd doesn't start due to a conflict with file descriptors:
Issue
The process is being started as user lighttpd, and of course has no permissions to set file descriptors, which is the essence of the problem.
The fix for this, is to install seutils.
Solution:
Install SE utils
Issue
# /etc/init.d/lighttpd restart
Stopping lighttpd: [FAILED]
Starting lighttpd: 2012-06-03 00:57:12: (server.c.722) couldn't set 'max filedescriptors' Permission denied
[FAILED]
The process is being started as user lighttpd, and of course has no permissions to set file descriptors, which is the essence of the problem.
The fix for this, is to install seutils.
Solution:
Install SE utils
yum install policycoreutils-pythonCreate SELinux module to allow lighttpd to set its own open file descriptors limit
/usr/sbin/semodule -DB
# /etc/init.d/auditd restart
Stopping auditd: [ OK ]
Starting auditd: [ OK ]
#grep lighttpd /var/log/audit/audit.log | audit2allow -M lighttpdmaxfds
#/usr/sbin/semodule -i lighttpdmaxfds.pp
# /etc/init.d/lighttpd restart
Stopping lighttpd: [FAILED]
Starting lighttpd: [ OK ]
# /usr/sbin/semodule -B
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