I created a transparent VPN Internet gateway tunnel (sorry, couldn’t come up with a better name for it) using OpenVPN and my new Odroid-C1 Linux mini computer. However, this will work with any Linux PC (including the Raspberry Pi). The beauty of a transparent VPN gateway is that a device in the LAN doesn’t have to know anything about the VPN. I don’t have to remember to turn on the VPN nor does it drain the battery on mobile devices to encrypt and decrypt the packets. The VPN is just “there”. On the other hand, mostly for performance reasons, I don’t want to encrypt all traffic leaving my home LAN, that’s why I didn’t set up the VPN in the existing router. 
I wanted to be able to choose, on a per-device basis, which devices will route their traffic unencrypted to my ISP and which devices will get their traffic encrypted and forwarded to the remote VPN server using a second gateway in my LAN. And all this without additional subnets in my LAN, VLANs or additional WiFi or Ethernet-adapters. This may not look like the brightest idea to everyone but it works for me and I wanted to document it to save time if I have to set it up again. This is not a step-by-step tutorial but should provide enough pointers to get started.
How to install Kodi on an Odroid-C1 as a standalone mediacenter
The Odroid-C1 ist just too cool not to have. This feature-packed ARM7 quad core Linux mini computer comes with an incredible price tag of $35. However, with all the accessories (RTC-battery, power supply, case, mini-HDMI cable, eMMC card, remote control…) and shipping from Korea, the final price is around $100. It’s going to replace my Raspberry Pi which I initially intended to use as a media center but it always felt a little too slow for the task, even with the highly tuned Raspbmc.
Since I wanted the Odroid-C1 to run Kodi without a desktop manager (but with an Ubuntu repository), I started off with the Ubuntu 14.04 minimal image provided by Hardkernel. Don’t forget to resize the root partition to its true size once the Odroid is up and running (and reboot again!). I’m recommending the Odroid-Utility for doing this. And while you’re at it, make sure to “Update udev rules for ODROID subdevices” in the “Update your Kernel/Firmware” menu. If you forget this step, Kodi might abort with ERROR: failed to initialize egl display.
I’m assuming here that the Odroid-C1 has network connectivity and you’re logged in as root.
With a few adaptations, this information was taken from my existing post on how to install Kodi on an Ubuntu 14.04 server. Continue reading
How to set up a virtual KVM/VNC console on your OVH server
Want to install your own image on a OVH Kimsufi or SoYouStart server? Want to install an official image on your server instead of the pre-built OVH OS templates? Want to encrypt the home directory at install-time? Want to use RAID 5 using mdadm on one of those SSD equipped SoYouStart servers? Or do you want to use a more refined, custom partition layout which is not supported by the OVH partitioner? And you want this without having access to or having to pay for a KVM console?
Continue reading
KVM VM waits forever / stuck at kernel selection screen
If a KVM virtual machine has not been properly shutdown, it may wait forever at the boot up kernel selection screen for user input. You won’t see any output when trying to virsh console into the VM from the host. You have to fire up a remote VNC session in order to press enter.
In Ubuntu Server you can override this behaviour by adding the following line to /etc/default/grub:
GRUB_RECORDFAIL_TIMEOUT=2
Don’t forget to run update-grub afterwards.
How to install Kodi on Ubuntu Server 14.04
I have a small Shuttle Barbebone computer which I’m mainly using as a KVM hypervisor on top of Ubuntu Server 14.04 to run a few VMs. Since the Barebone also sports a HDMI port and the CPU comes with an integrated Intel HD GPU I thought it would be a great Kodi (ex XBMC) mediacenter as well. However, I’ve been unable to find a working walk-through on how to install it on Ubuntu Server. Most likely because nobody ever does this on a server OS. Anyway, here’s how to install the latest Kodi release on Ubuntu Server 14.04 including hardware acceleration for the Intel HD GPU. Continue reading
QEMU on Haswell causes spurious MCE events
A few dozen times each day, the Xeon E3-1275 v3 CPU on my SuperMicro X10SLM-F board generates a Machine Check Event (MCE). The Linux kernel logs all MCEs in /var/log/syslog:
mce: [Hardware Error]: Machine check events logged mce: [Hardware Error]: Machine check events logged CMCI storm detected: switching to poll mode CMCI storm subsided: switching to interrupt mode mce_notify_irq: 14 callbacks suppressed mce: [Hardware Error]: Machine check events logged mce: CPU supports 9 MCE banks mce: [Hardware Error]: Machine check events logged
After installing mcelog I was able to pull some more detailed information about the check events:
Hardware event. This is not a software error. MCE 0 CPU 3 BANK 0 TIME 1415087019 Tue Nov 4 08:43:39 2014 MCG status: MCi status: Corrected error Error enabled MCA: Internal parity error STATUS 90000040000f0005 MCGSTATUS 0 MCGCAP c09 APICID 6 SOCKETID 0 CPUID Vendor Intel Family 6 Model 60
The MCEs all look the same (affected is always BANK 0), just the CPU and the APICID may differ. I updated the BIOS, replaced the ECC RAM, replaced the mainboard but the errors kept showing up. Continue reading
OS X Yosemite installer shows blank/black screen when using Clover
This is a heads up for everybody with an Nvidia GTX 760 (other Nvidia cards may be affected as well) trying to install OS X Yosemite 10.10 using Clover on a Hackintosh. If you’re getting a blank/black screen at the start of the installation, try to add the boot flag nv_disable=1. My screen was getting dark just after the installer displayed DSMOS has arrived when using the -v verbose boot flag. It always happened right after the installer was switching from text mode to graphics mode.
<key>Boot</key>
<dict>
<key>Arguments</key>
<string>dart=0 -v kext-dev-mode=1 nv_disable=1</string>
...(more)
Once OS X Yosemite has been installed, the nv_disable boot flag is no longer required and should be removed.
Ubuntu release upgrade says ‘no new release found’ on IPv6-only server
I’m running some sort of an experimental KVM guest with IPv6 connectivity only. Since it still had Ubuntu Server 13.10 installed I tried to run a do-release-upgrade on it to upgrade it to the latest Ubuntu Server release – which at the time of this writing is 14.10. However, the do-release-upgrade command kept saying that no new release could be found:
root@ipv6lab:~# do-release-upgrade Checking for a new Ubuntu release No new release found
I verified the /etc/update-manager/release-upgrades configuration file but it already contained the Prompt=normal line. After doing some digging I found out that the do-release-upgrade tries to connect to http://changelogs.ubuntu.com but there is no AAAA DNS record for this host. Essentially, this means that an Ubuntu server can’t be upgraded to a newer release over IPv6 because it can’t connect to the update info site over IPv6.
root@ipv6lab:~# dig +short changelogs.ubuntu.com A 91.189.95.36 root@ipv6lab:~# dig +short changelogs.ubuntu.com AAAA root@ipv6lab:~#
Interestingly, the Ubuntu APT repository update site is accessible over IPv6, which is why something like apt-get update runs fine on IPv6-only Ubuntu servers.
I solved the problem by creating an IPv6 to IPv4 HTTP proxy using HAProxy on a IPv4/IPv6 dual stack server. The proxy listens on an IPv6 address and “tunnels” all requests to changelogs.ubuntu.com using the IPv4 address of the changelogs server. I was able to upgrade to a newer Ubuntu release this way on an IPv6-only Ubuntu server. Continue reading
How to comfortably mount Clover’s EFI partition
I’ve been using command-line commands or the Clover Configurator to mount Clover’s EFI partition to edit Clover’s main configuration file.
However, I find it easiest to mount the hidden EFI volume in Disk Utility:
The hidden partitions will only be shown if Disk Utility’s debug mode has been enabled. In a shell, type:
defaults write com.apple.DiskUtility DUDebugMenuEnabled 1
Start Disk Utility and enable the option to show all partitions:
How to auto-boot an OS X Fusion Drive using Clover
Ever since I fusioned a SSD and a HDD into an OS X Fusion Drive, Clover has been unable to auto-boot the new logical Fusion Drive volume. Clover was just sitting on its startup volume selection screen and was waiting for me to select the volume to boot. I’ve found some hints that using an UUID should make Clover autoboot the Fusion drive but I’ve been unable to make it work with any of the UUIDs of the logical/physical volume.
What finally worked was using the system ID (or whatever this is called) of the volume. Here’s an excerpt from my Clover configuration:
<key>Boot</key> <dict> <key>Arguments</key> <string>dart=0</string> <key>DefaultVolume</key> <string>HD(3,GPT,17337FC1-A0F7-4C73-DEA1-363BA11AB811,0x3A346008,0x40000)</string> <key>Timeout</key> <integer>5</integer>
With this ID, Clover auto-boots my Fusion Drive volume just fine after waiting for 5 seconds for user input.
The full IDs can be found in Clover’s log file in /Library/Logs/CloverEFI/ and look like this:
system.log:0:837 0:000 PciRoot(0x0)\Pci(0x1F,0x2)\Sata(0x0,0xFFFF,0x0)\HD(3,GPT,17337FC1-A0F7-4C73-DEA1-363BA11AB811,0x3A346008,0x40000)
You have to strip the PciRoot/Sata part for Clover.
How to rename an OS X Fusion Drive
Since OS X Yosemite, the CoreStorage service allows you to rename the logical volume name of a Fusion Drive if you wish to do so.
sudo diskutil cs rename "Macintosh HD" "Fusion Drive"
The Fusion Drive now shows up as “Fusion Drive” instead of “Macintosh HD” which was the name I’ve chosen initially. The OS X main volume is still named “Macintosh HD”.
Could not load host key: /etc/ssh/ssh_host_ed25519_key
Sep 29 19:19:41 wopr sshd[11801]: error: Could not load host key: /etc/ssh/ssh_host_ed25519_key
If you’re getting this error message in the log file, you most likely have the ed25519 HostKey enabled in your sshd_config file but for some reason, no host key was generated for it.
Since openssh-6.4 you can run the ssh-keygen command to generate any missing host keys:
$ ssh-keygen -A ssh-keygen: generating new host keys: ED25519
Enable KVM guest console access in Ubuntu using the virsh console command
Usually, my first step after setting up a new Ubuntu guest is to enable console access in order gain shell access on the newly created VM.
Step 1 – Activate the serial console in the guest
nano /etc/default/grub
Change the GRUB_CMDLINE_LINUX_DEFAULT to:
GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0,38400n8 console=tty0"
Don’t forget to update Grub
update-grub
Step 2 – Create the serial console in the guest
cp /etc/init/tty1.conf /etc/init/ttyS0.conf nano /etc/init/ttyS0.conf
Edit ttyS0.conf and replace the tty1 with ttyS0 in the last line so it will read something like “exec /sbin/getty -8 38400 ttyS0″.
Reboot the VM.
Step 3 – Log in from the host
virsh console myvm
This is it! You just gained console access to your VM.
Tip: To exit the console, hit CTRL-]. It doesn’t matter where the ] is located on your keyboard, you have to press the key below the <BACKSPACE> key and on the left side of the <ENTER> key.
How to install CoreOS on an OVH Kimsufi low-end dedicated server
Wouldn’t it be cool to build a bare-metal high availability cluster using CoreOS and a handful of DDoS-protected, €5/month Kimsufi servers from OVH? Here’s how to install CoreOS on a Kimsufi server.
At the time of this writing, OVH is not providing a CoreOS installation template for the Kimsufi servers. Since there is no virtual KVM console available for the entry level servers, I tried to use OVH’s iPXE API. This approach would have worked well weren’t it for the CoreOS installer which tries to load binaries in the installation script after overwriting the same partition – which always results in a segfault. Also, the API is only available for the older Kimsufi 2G servers on OVH’s V6 control panel, not for the current Kimsufi servers for which OVH doesn’t provide an API at this time. Fortunately, OVH provides a “rescue mode” which lets us boot from an USB stick which is permanentely plugged in on all Kimsufi servers. Continue reading
Native Gigabit PCI-e Network Adapter / NIC for OS X
Here’s an overview of natively supported PCI-e (64-bit) network interface controllers (NIC) for OS X. I’ve had the chance to test some of them in my current Hackintosh build.
HP NC360T PCI-Express PRO/1000
The HP NC360T dual port PCI-e network adapter works out of the box in OS X. However, since OS X 10.8.2 Apple changed something in the driver resulting in a link loss whenever the network is under considerable load. If this happens, the network can be brought back to life by deactivating/reactivating the network in OS X’s control panel. Do not buy this network card if you intend to use it in a recent OS X version.
Continue reading