How to log history and logins from multiple ssh-keys under one user account

Many times your managed server has only one user account into wich every admin logs in with his personal ssh-key. Most times it’s done with the root account, but that’s a nother topic 😉 As a result of this behaviour your are not able to see who logged in and what he or she did. A often suggested solution would be using different user account per person with only one ssh-key for authorization. This adds the „overhead“ of memorizing (except when you use ~/.ssh/config) and managing the sudoers file for all the accounts.

A more clever way is to use the SSH Environment feature in your authorized_keys file. First you need to enable this feature within the /etc/sshd/sshd_config file:

PermitUserEnvironment yes

After that you can configure your ~/.ssh/authorized_keys file:

environment="SSH_USER=USER1" ssh-rsa AAAAfgds...
environment="SSH_USER=USER2" ssh-rsa AAAAukde..

This sets the SSH_USER variable on Login in reference to the used ssh-key. NOw that this variable is updated on every login you can go on and work with it. First of to the logging of the actuall key that logs in. Under normal circumstances the ssh-dameon logs only the following information

sshd[21169]: Accepted publickey for user_account from port 46416 ssh2

Additinally you could pass the SSH_USER content on to the syslog-dameon to log the actual user:

if [ "$SSH_USER" != "" ]; then
  logger -ip auth.notice -t sshd "Accepted publickey for $SSH_USER"

This writes the following into the /var/log/auth (Debian) or /var/log/messages (RedHat) file:

sshd[21205]: Accepted publickey for USER1

Further more you can change the bash history file to a personal user file:

  export HISTFILE="$HOME/.history_$SSH_USER"


All together it looks like this:

if [ "$SSH_USER" != "" ]; then
  logger -ip auth.notice -t sshd "Accepted publickey for $SSH_USER"
  export HISTFILE="$HOME/.history_$SSH_USER"


To use the environment option within your ssh-key management in puppet you need the options field from the ssh_authorized_key function:

ssh_authorized_key { "${username}":
  key     =>  "AAAAsdnvslibyLSBSDFbSIewe2131sadasd...",
  type    =>  "ssh-rsa,
  name    =>  "${username}",
  options =>  ["environment=\"SSH_USER=${username}\""],
  user    =>  $user,
  ensure  =>  "present",


Hope this helps, have fun! :)

p.s.: This is a guest post by Martin Mörner, a colleague from Aperto.

RubyGems 9.9.9 packaged – Fake install RubyGems on Debian/Ubuntu

For a lot of reasons I often rely on a mixture of a Debian/Ubuntu pre packaged Ruby with a self compiled RubyGems. It helps you in situations where you don’t care that much about the Ruby interpreter itself but need an up to date RubyGems. While this is easy to install, you might run into trouble when installing packages that depend on Ruby and RubyGems, namely packages like „rubygems“, „rubygems1.8“ and „rubygems1.9“.

After unsuccessfully playing around with dpkg for a while (you can put packages on „hold“ which prevents them from being installed automatically, I came to the conclusion, the best way is to install a fake package that is empty but satisfies depencies.

So, here it is: The shiny new RubyGems 9.9.9 which delivers rubygems, rubygems1.8 and rubygems1.9 right away. Just install it (e.g. with dpkg) and you’ll be able installing packages that rely on a rubygems package.

In case you want to play around with the package and customize it to your needs, e.g. only deliver rubygems1.8 or rubygems1.9, take

1. Install equivs

$ sudo apt-get install equivs

2. create a control file

$ equivs-control rubygems

3. edit the control file

$ vim rubygems

You can compare the default settings in the control file with the output of e.g. „apt-cache show rubygems“. The crucial field is „Provides:“ where you can put a comma separated list of packages you want to fake install. Choose a high version for  there „Version: “ field as this will mark the package newer as the distribution’s own package. This prevents the packager from replacing it.

Section: universe/interpreters
Priority: optional
Standards-Version: 3.6.2
Package: rubygems
Version: 9.9.9
Maintainer: Caspar Clemens Mierau <[email protected]>
Provides: rubygems1.8,rubygems1.9,rubygems
Architecture: all
Description: Fake RubyGems replacement
 This is a fake meta package satisfying rubygems dependencies.
 This package can be used when you installed a packaged ruby but want
 to use rubygems from source and still rely on software that depends
 on ruby and rubygems

4. build the package

$ equivs-build rubygems

p.s.: You can also use equivs for easily building meta packages containing a list of packages you want to install at a glance, e.g. for semi automated server bootstrapping.

Bootstrapping a Puppet agent/master on Ubuntu

Though it’s really great that Puppet made it into Ubuntu’s main repository, the provided version is rather outdated which prevents you from using advanced language features when writing your manifests. So sooner or later you end up installing Puppet manually. In order to speed up installation I stripped it down to the following:

install agent:

$ bash &lt; &lt;(wget -qO -

install master:

$ bash &lt; &lt;(wget -qO -

The call fetches the most recent version of the install script from github, installs Ubuntu’s Ruby (which is good enough for running Puppet), fetches an upstream version of gem itself and updates it to the most recent version and finally installs the Puppet gem.

You can, of course, also download, review and run the scripts manually. Just have a look at