systemd – abstract

Rescue Mode

cmdline=…systemd.unit=rescue.target

Analyzing the boot process

* systemd-analyze
* systemd-analyze blame
* systemd-analyze plot > /tmp/plot.svg

Start/Stop/Disable services

* systemctl start/stop/restart/mask [service]
* systemctl daemon-reload
* systemctl list-units –type=[timer,service,target,mounts,…]

Journal

* journalctl -u ssh
* _PID=1
* -b

Custom unit

http://www.freedesktop.org/software/systemd/man/systemd.unit.html

Retrieve Windows key from ACPI MSDM table

[root@localhost ~]# hexdump -C /sys/firmware/acpi/tables/MSDM
00000000 4d 53 44 4d 55 00 00 00 03 d3 4c 45 4e 4f 56 4f |MSDMU.....LENOVO|
00000010 54 50 2d 47 32 20 20 20 70 25 00 00 50 54 4c 20 |TP-G2   p%..PTL |
00000020 02 00 00 00 01 00 00 00 00 00 00 00 01 00 00 00 |................|
00000030 00 00 00 00 1d 00 00 00 XX XX XX XX XX XX XX XX |........xxxxx-xx|
00000040 XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX XX |xxx-xxxxx-xxxxx-|
00000050 XX XX XX XX XX                                  |xxxxx|
00000055
cat /sys/firmware/acpi/tables/MSDM | dd bs=1 skip=56 2>/dev/null

Ahh yes…and thanks to everyone how post a howto with screenshots with black bars – don’t forget the hexdump 😉

Syncing a fork with git/github

  • Configure a remote
    git remove -v
    # git remote add <name> <url>
    git remote add upstream https://github.com/foo/bar.git
    git remove -v
  • Pull “upstream”
    # git fetch <name>
    git fetch upstream
  • Checkout the master
    git checkout master
  • Merge “upstream” master to local master
    # git merge <name>/<branch>
    git merge upstream/master
  • (optional) Delete old branch
    # git push origin :<branch>
    git push origin :foobar
    git branch -d foobar

Refs https://help.github.com/articles/

OS X Mavericks and MacPorts

A few weeks ago i upgraded to Mavericks (10.9)…so far, so good.

But i had some trouble with my MacPorts installation…

:info:configure CMake Error at Modules/Platform/Darwin.cmake:211 (message):
:info:configure   CMAKE_OSX_DEPLOYMENT_TARGET is '10.9' but CMAKE_OSX_SYSROOT:
:info:configure 
:info:configure    ""
:info:configure 
:info:configure   is not set to a MacOSX SDK with a recognized version.  Either set
:info:configure   CMAKE_OSX_SYSROOT to a valid SDK or set CMAKE_OSX_DEPLOYMENT_TARGET to
:info:configure   empty.

On https://trac.macports.org was this problem already reported but without any solutions that worked for me. So i did my own research and i ended up with a really dirty workaround.

Create a list of all installed ports (incl. variants)

sudo port -qv installed

Uninstall all ports

sudo port -f uninstall installed

Clean any builds

sudo port clean all

Reinstall all necessary ports

port install <port> +variant1

Yeah…it’s not the best… i know!

Create a shared disk for VMware ESX guests

To create a shared disk between two or more VMs, login into one of your ESX hosts and create a disk image.

cd /vmfs/volumes/#volume-name#/#vm-name#/;
vmkfstools -d thick -a lsilogic -c 50G shareddisk.vmdk;

Add the new hardrive to the guest(s) and select a new SCSI bus (like SCSI 2:0). VMware create a new SCSI controller. Set SCSI Bus Sharing = Physical or Virtual and have fun 🙂

Linux routing basics

You getting from your ISP a subnet like this 172.30.26.16/28,
and your router has the ip 172.30.26.17 !

You need to enable the ip forwarding in the kernel

sysctl -w net.ipv4.ip_forward=1

And we need to enable proxy arp! This is necessary because your router must answer all arp request for hosts other than itself 😉

sysctl -w net.ipv4.conf.eth0.proxy_arp=1
sysctl -w net.ipv4.conf.eth1.proxy_arp=1

Edit your /etc/sysctl.conf !

net.ipv4.ip_forward = 1
net.ipv4.conf.eth0.proxy_arp = 1
net.ipv4.conf.eth1.proxy_arp = 1

If your router has no external ip on the internal nic, you need to setup routes like

route add -host 172.30.26.20 gw 192.168.10.20 eth1

Ubuntu PHP hardening with Suhosin

Ubuntu includes the php suhosin patches….

Install suhosin extension

aptitude install php5-suhosin

/etc/php5/{apache2,cli,cgi}/php.ini

; suhosin parameters
suhosin.executor.include.max_traversal = 4
suhosin.executor.disable_eval = On
suhosin.executor.disable_emodifier = On
suhosin.mail.protect = 2
suhosin.sql.bailout_on_error = On

Restart apache

service apache2 restart

Sometimes it could be necessary to set suhosin.session.encrypt to off for some login scripts.

How to delete a command from the bash history / Hide an command from the bash history

Hide an command from the bash history:
Start a terminal and try

wget user:passwd@ftp.example.com/secret.tar.gz; kill -9 $$;

Now you can check your history 😉

How to delete a command from the bash history:
If you have already such an entry, you can use history to delete it.

history
# [...]
# 849 uname -a
# 850 wget user:passwd@ftp.example.com/secret.tar.gz
# 851 ping blog.devnu11.net
# [...]

Now you can delete your history with history -d 850 this line.

history -d 850

And see…

history
# [...]
# 849 uname -a
# 850 history
# 851 ping blog.devnu11.net
# [...]

Or simply add a blank before the command 😉

$  wget user:passwd@ftp.example.com/secret.tar.gz