PassHash sha512 support

June 9, 2013

I added sha512 support to the PassHash firefox extension here (and added pull request to get it into the upstream branch). I felt its important to do this after reading this article.

ansible ad-hoc data gathering

June 1, 2013

When using ansible and its “setup” module to gather ad-hoc facts-data about multiple hosts, remember that it runs the jobs in parallel which may result in out-of-order output. With “ansible -f1” the number of parallel processes can be limited to one to ensure this won’t happen. E.g.:

$ ansible all -f1 -m setup -a filter=ansible_mounts

(the filter argument for the facts module is also a nice feature).

Ansible and the facts from the “setup” module

May 30, 2013

I recently started using ansible to automate some server administration tasks.

Its very cool and easy to learn/extend. One nice feature is the “facts” gathering. It will collect information about the host(s) and stores them in its internal variables. This is useful for conditional execution of tasks (see below) but also as a ad-hoc way to gather information like DMI information or the running kernel.

To see all “facts” known to ansible about the hosts, run:

$ ansible all -m setup

To execute tasks conditionally you can do something like this:

- name: install vmware packages
  action: apt pkg=open-vm-tools
  only_if: "'$ansible_virtualization_type' == 'VMware'"

Note that ansible 1.2+ has a different (and simpler) conditional called “when”.

Ansible is available in Ubuntu 12.04+ via:

$ sudo apt-get install ansible

It is also available in Debian unstable and testing.

git fast-import apt

May 16, 2013

Due to popular demand I moved debian apt and python-apt from bzr to git today. Moving was pretty painless:

$ git init
$ bzr fast-export --export-marks=marks.bzr -b debian/sid /path/to/debian-sid | git fast-import --export-marks=marks.git

And then a fast-import for the debian-wheezy and debian-experimental branches too. Then a

$ git gc --aggressive

(thanks to Guillem Jover for pointing this out) and that was it.

The branches are available at:

Webkitgtk & SSL

April 30, 2013

For a project of mine I created a small app based on webkitgtk that talks to a SSL server.

And I almost forgot about the libsoup default behavior for SSL certificates checking. By default libsoup and therefore webkitgtk will not do any SSL certificate checks. You need to put something like the following snippet into your code (adjust for your language of choice):

from gi.repository import WebKit

session = WebKit.get_default_session()
session.set_property("ssl-use-system-ca-file", True)

If you don’t do this it will accept any certificate (including self-signed ones).

This is documented behavior in libsoup and they don’t want to change it for compatiblity reasons in libsoup. But for webkit its unexpected behavior (at least to me) and I hope the webkitgtk developers will consider changing this default in webkit. I filed a bug about it. So if you use webkitgtk and SSL, remember to set the above property.

PassHash cmdline

April 18, 2013

I use the PassHash firefox extension to generate site-specific strong passwords. The idea behind the extension is that a master password and a siteTag (e.g. the domain name) is used to generate a sha1 hash. This hash is used as the password for the website. In python its essentially this code:

h = hmac.new(master_pass, site_tag, hashlib.sha1)
print(b64encode(h.digest())[:hash_len])

I want a commandline utility that can output me PassHash compatible hashes when I use w3m (or if the extension stops working for some reason).

To my delight I discovered that the upstream git repNice and hard to brute-force.o of PassHash already has a python helper to generate passhash compatible password. I added some tweaks to add pythons argparse [1] and now I’m really happy with it:

$ ./tools/passhash.py --hash-size 14 slashdot.org
Please enter the master key: 
KPXveo7bq7j1%X

Hard to brute-force and matches what the extension generates.

squid-deb-proxy for Debian

April 11, 2013

I uploaded squid-deb-proxy into Debian unstable today and its in the NEW queue. I created it back in the days of Ubuntu 10.04 and some people voiced interest in having it in Debian as well so I spend a bit of time to get it customized for Debian.

Squid-deb-proxy uses the well known squid proxy with a custom configuration to cache deb package and Indexfiles (like Packages.gz) that will allow caching from the default archives and mirrors and reject anything else by default.

The basic philosophy is that “it just works”. You run on your server:

root@server# apt-get install squid-deb-proxy

and on your clients:

root@client# apt-get install squid-deb-proxy-client

and that’s it. It does not require any fiddling with configuration (unless you want to 😉 ). The default will let you connect to .debian.org and nothing else.

The server will announce itself via avahi as _apt_proxy._tcp and the
client will hook into apt to use Acquire::http::ProxyAutoDetect. The
client is useful for other servers that announce themself via avahi.

Packaging was a bit more work than anticipated because there is a bit of setup and teardown work in the initscript. For Debian as sysvinit script was needed, Ubuntu uses upstart so it took a bit of refactoring to extract the code into a common helper.

If you want to try it now, its available via:

$ bzr branch lp:squid-deb-proxy
$ cd squid-deb-proxy
$ bzr-buildpackage

and in unstable once it leaves the NEW queue.

Fun with sqlite/fts

March 27, 2013

A while ago I played with sqlite. Its pretty awesome. When using the full text search (fts) extension it also provides super fast full text searching. One of the things I was missing (compared to other engines) is the similar text suggestion (“Did you mean?”) support. Fortunately this is relatively easy to add via the fts4aux virtual table that sqlite supports.

I pushed a full example of to https://github.com/mvo5/sqlite-fts-did-you-mean. The way it works is that you build a set of similar words and use that to query for the “term” value from the fts4aux table.

Here is the output from the example:

$ ./fts_did_you_mean.py aptx
Did you mean:
 apex (rank: 2)
 apt (rank: 1)
time 0.024138927459716797

Using gdebi to install build-dependencies

March 22, 2013

I wrote gdebi a long time ago to make it really easy to install .deb package with proper dependency resolution from the commandline and via a gtk (and kde) UI. But another neat (but not very well known) feature of the gdebi-core cli tool is to install the build-dependencies of a debian source package. If you run:

$ gdebi debian/control

in a unpacked debian source package it will check for missing build-dependencies and offer to install them.

New unattended-upgrades for debian/experimental

March 16, 2013

There is a new 0.80~exp2 version of unattended-upgrades available. This would normally be fine for debian/sid but because of the freeze I decided to put it into experimental. Some nice features like adding a “–verbose” mode that shows the actual dpkg output when
running and codename based matching plus some nice fixes from Brian Murray (thanks!).

The codename based matching is interessting as it allows writing a matcher like “n=wheezy” (or more verbose “codename=wheezy”) in the config file. You can use “apt-cache policy” (without further arguments) to see what origins are available.

Enjoy and let me know if you find any issues issues!