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node fun

September 19th, 2015 No comments


$ node
> "5" + "1"
'51'
> "5" - "1"
4

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Ars Hacker Movie Madness

March 8th, 2015 3 comments

http://arstechnica.com/the-multiverse/2015/03/vote-for-the-final-four-of-ars-march-hacker-movie-madness/

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News Server

February 24th, 2015 No comments

Hi,

i moved the blog (which is more of an archive of the good ol’ times these days) to a new server. Lets see if everyhting still works . . .

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Secret Coders

September 5th, 2014 No comments

Really nice graphic novel about how to learn coding.

http://www.wired.com/2014/09/secret-coders-gene-yang

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adding pci device to vm

August 27th, 2014 8 comments

If you want to use a pci device in a vm, you first have to detach it from the host. List the devices and look for the one you want to use in the vm:

virsh nodedev-list --tree

In my case (CentOS7) I needed to enable iommu in order for this to work. This involves adding a kernel parameter:

kpath=`grubby --default-kernel`
grubby --update-kernel=$kpath --args="intel_iommu=on”
cat /proc/cmdline

After the reboot, /proc/cmdline should now include the iommu flag. Also check whether all the needed modules are loaded, in my case these are:

  • vfio_pci
  • vfio_iommu_type1
  • vfio
  • kvm_intel
  • kvm

You can then detach the pci device:

virsh nodedev-dettach pci_0000_05_00_1

I then used virt-manager, powered off the vm, and added the “Physical Host Device”.

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virt-manager as non-root user

August 26th, 2014 No comments

trying to start virt-manager as a normal user will yield a “Unable to open a connection…” message. To fix this, we need to change access permissions for libvirtd.

Edit /etc/libvirt/libvirtd.conf:

echo "unix_sock_group = \"libvirt\"
unix_sock_rw_perms = \"0770\"
auth_unix_rw = \"none\"
">>/etc/libvirt/libvirtd.conf

We also jneed to create the group “libvirt” we just set:

groupadd -g $GID libvirt; usermod -a -G libvirt $USER

Be sure to set $GID and $USER correctly.

A restart of the daemon should then do the trick:

service libvirtd stop; service libvirtd start

if virt-manager the shows only squares instead of letters, install the necessary fonts:

yum -y groupinstall "Fonts"

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heartbleed

April 8th, 2014 1 comment

Enough word already on all channels, here’s a short one-liner to check which procs are still using the vulnerable old libs after the upgrade:
sudo lsof -n | grep ssl | grep DEL

Oh, and if you want to test wether a site is still vulnerable: https://gist.github.com/takeshixx/10107280

Time to revoke all those lingering server certs . . .

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pbpaste and pbcopy in tmux (and screen) on mac os x

March 27th, 2014 2 comments

the pasteboard tools do not work in tmux on a mac. But there is a tool to fix this (of course ^^):
brew install reattach-to-user-namespace

Then, in your .tmux.conf, add this:
set-option -g default-command "reattach-to-user-namespace -l zsh"
– more info on how to configure can be fiound here: https://github.com/ChrisJohnsen/tmux-MacOSX-pasteboard/blob/master/Usage.md

After restarting your tmux server, pbcopy and pbpaste should work again.

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change shell on a mac

February 6th, 2014 1 comment

Hi,

trying to change my login shell to zsh using the zsh built with homebrew i faced a small issue as OS X claimed:
chsh: /usr/local/bin/zsh: non-standard shell

The solution was to add the shell to the “approved” list:
echo "/usr/local/bin/zsh" >/etc/shells

The a simple chsh -s /usr/local/bin/zsh will do the trick.

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Pipe view

February 4th, 2014 2 comments

a rather handy little helper is simply called “pv” – pipe view. I mainly use it when copying vms or lots of small files:
tar cf - ./src | pv --timer --rate --average-rate --bytes | ssh machine tar xpf - -C /dst
which then prints something like this:
4.54GiB 0:06:55 [11.2MiB/s] [11.2MiB/s]

pv can also be used to set a rate limit to the transfer using “-L 1m” to restrict the bandwidth to 1 MB/s. For the Mac users out there – homebrew has knows “pv”.

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