Hurricane Electric IPv6 tunnel MTU

I’ve been running an IPv6 tunnel for a long time, but occasionally I’ve been seeing traffic hang on it. It looks like it was the MTU, defaulting at 1500 bytes, causing issues when large amounts of data were being shuffled OUT from my Linux box, back to the ‘net’.

The fix is easy: /etc/network/interfaces should have an “up” line for the interface definition saying: up ip link set mtu 1280 dev henet, where henet is the name of your tunnel interface.

Easy enough to skip this line if your tunnel appears to be working OK, but interesting to track down.

Debian Wheezy: US$19 Billion. Your price… FREE!

As many would know, Debian GNU/Linux is one of the oldest, and the largest Linux distributions that is available for free. Since it was first released in 1993, several people have analysed the size and produced cost estimates for the project.

In 2001, Jesús M. González-Barahona et al produced an article entitled “Counting Potatoes“, an analysis of Debian 2.2 (code named Potato). When Potato was released in June 2003, it contained 2,800 source packages of software, totalling around 55 million lines of source code. When using David A. Wheeler’s sloccount tool to apply the COCOMO model of development, and an average developer salary of US$56,000, the projected development cost that González-Barahona calculated to start-from-scratch and build Debian 2.2 in 2003 was US$1.9 billion.

In 2007 an analysis entitled ‘Macro-level software evolution: a case study of a large software compilation‘ by Jesús M. González-Barahona, Gregorio Robles, Martin Michlmayr, Juan José Amor and Daniel M. German was released. It found that Debian 4.0 (codename Etch released April 2007) had just over 10,000 source packages of software and 288 million lines of source code. This analysis also delved into the dependencies of software packages, and the update flow between Debian release (not all packages are updated with each release).

Today (February 2012) the current development version of Debian, codenamed Wheezy, contains some 17,141 source packages of software, but as it’s still in development this number may change over the coming months.

I analysied the source code in Wheezy, looking at the content from the “original” software that Debian distributes from its upstream authors without including the additional patches that Debian Developers apply to this software, or the package management scripts (used to install, configure and de-install packages). One might argue that these patches and configuration scripts are the added value of Debian, however the in my analysis I only examined the ‘pristine’ upstream source code.

By using David A Wheeler’s sloccount tool and average wage of a developer of US$72,533 (using median estimates from and for 2011) I summed the individual results to find a total of 419,776,604 source lines of code for the ‘pristine’ upstream sources, in 31 programming languages — including 429 lines of Cobol and 1933 lines of Modula3!

In my analysis the projected cost of producing Debian Wheezy in February 2012 is US$19,070,177,727 (AU$17.7B, EUR€14.4B, GBP£12.11B), making each package’s upstream source code wrth an average of US$1,112,547.56 (AU$837K) to produce. Impressively, this is all free (of cost).

Zooming in on the Linux “Kernel”

In 2004 David A. Wheeler did a cost analysis of the Linux Kernel project by itself. He found 4,000,000 source lines of code (SLOC), and a projected cost between US$175M and US$611M depending on the complexity rating of the software. Within my analysis above, I used the ‘standard’ (default) complexity with the adjusted salary for 2011 (US$72K), and deducted that Kernel version 3.1.8 with almost 10,000,000 lines of source code would be worth US$540M at standard complexity, or US$1,877M when rated as ‘complex’.

Another Kernel Costing in 2011 put this figure at US$3 billion, so perhaps there’s some more variance in here to play with.

Individual Projects

Other highlights by project included:

Project Version Thousands
Projected cost
at US$72,533/developer/year
Samba 3.6.1 2,000 US$101 (AU$93M)
Apache 2.2.9 693 US$33.5M (AU$31M)
MySQL 5.5.17 1,200 US$64.2M (AU$59.7M)
Perl 5.14.2 669 US$32.3M (AU$30M)
PHP 5.3.9 693 US$33.5M (AU$31.1M)
Bind 9.7.3 319 US$14.8M (AU$13.8M)
Moodle 1.9.9 396 US$18.6M (AU$17.3M)
Dasher 4.11 109 US$4.8M (AU$4.4M)
DVSwitch 6 US$250K (AU$232K)

Debian Wheezy by Programming Language

The upstream code that Debian distributes is written in many different languages. ANSI C with 168,536,758 is the dominant language (40% of all lines), followed by C++ at 83,187,329 (20%) and Java with 34,698,990 (8%).

Line chart
Break down of Wheezy by Language

If you are intersted in finding the line count and cost projections for any of the 17,000+ projects, you will find them in the raw data CSV.

Other Tools and Comparisons

Ohcount is another source code cost analysis tool. In March 2011 Ohcount was run across Debian Sid: its results are here. In comparison, its results  appear much lower than the sloccount tool. There’s also the Debian Estimate which only finds 55 Million source lines of code and a projected cost of US$1B. However Ohloh uses Ohcount for its estimates, and seems to be to be around 370 million SLOC missing compared to my recent analysis.


Over the last 10 years the cost to develop Debian has increased ten-fold. It’s intersting to know that US$19 billion of software is available to use, review, extend, and share, for the bargain price of $0. If we were to add in Debian patches and install scripts then this projected figure would increase. If only more organisations would realise the potential they have before them.

Need help with Linux (including Debian), Perl, or AWS? See