Weird commit log

I stumbled upon something strange on page 895 of Swedish TV4’s teletext:


This is clearly counting the number of commits in source code repositories, but why is this information in the teletext system?

Favorite podcasts

About a year ago I discovered the delights of listening to podcasts, and I have done so practically daily during my commute. Unfortunately, the screen on my phone recently went black and for a while I thought my feeds were lost. I did eventually managed to extract them, so now I’m making a public backup, in the form of podcast recommendations:

60-Second Space (RSS) is one of several bite-sized podcasts from Scientific American. Since it’s so short I seldom remember anything, but when queued up it can serve as an overview of recent space news.

Discovery (RSS) is a science podcast from the BBC.

Freethought Radio (RSS) is a podcast with news, music and interviews from the Freedom from Religion Foundation. The news is rather US-specific, so I just pick the episodes with interesting interviews.

Humanistpodden (RSS) is the official podcast of Humanisterna, a Swedish secular humanist organization. Some episodes are in English, e.g. the excellent interviews with Ophelia Benson and Peter Singer.

Little Atoms (RSS) is a “talk show about ideas and culture.” The host sounds like a really nice guy, maybe it’s the British accent?

Planetary Radio (RSS) is the Planetary Society’s show with news and interviews. It sounds very scripted and a bit dry, but the actual content is interesting.

Red Planet Radio (RSS) is a newly launched podcast from the Mars Society.

Science Talk (RSS) is a science podcast from Scientific American.

Science Weekly (RSS) is a science podcast from The Guardian.

Skeptoid (RSS) is my probably my favorite podcast, see my previous post for episode recommendations.

Språket (RSS) is a Swedish radio show about the Swedish language, and is what got me started listening to podcasts.

StarStuff (RSS) is by far the best space podcast that I have found. The host, Stuart Gary, has a nice Australian accent and appears to be incredibly knowledgeable when interviewing the authors of recent papers, etc.

The Atheist Experience (RSS) is actually a call-in TV show from Austin, Texas, but I listen to it as a podcast. I recommended episode #795 on Twitter, with my favorite hosts Tracie Harris and Matt Dillahunty.

I’ve prepared an OPML file with all 13 feeds for importing. I can recommend DoggCatcher for Android if you don’t already have a podcast player.

Favorite Skeptoid episodes

Skeptoid is an excellent podcast for a skeptical treatment of paranormal claims, conspiracy theories, alternative medicine, etc. Over the past 8 months or so I’ve listened to every episode up to and including #376, and I thought I would share my favorites. The most reward episodes have often been those challenging my own beliefs, since those open the door to learning something new.

Happy listening!

Send mail the first time an IP logs in over SSH

Fail2ban is useful for slowing down brute force attacks against SSH, and in the few days since I enabled it it’s become very clear that these attempts are happening all the time. I don’t want to disable password authentication for all users in case I find myself without my SSH keys, and even if I did it’s not impossible for SSH keys to be compromised. For the day when the walls are breached, I’ve put this in my /etc/ssh/sshrc:

IP="$(echo $SSH_CONNECTION | awk '{print $1}')"
if ! grep -Fqsx $IP $KNOWN_IPS; then
  echo $IP >> $KNOWN_IPS
  echo "$IP added to $KNOWN_IPS" | \
    mail -s "ssh $USER@$(hostname) from $IP"

It sends me an email the first time a particular IP successfully logs in over SSH. (If you use this, make sure that mail is configured correctly first: dpkg-reconfigure exim4-config in Debian.)

Web hosting

About a month ago, I began looking for a new hosting solution for, having started with a wardrobe computer in 2006 and never really having found a stable home. My needs are modest, so I went shopping for the cheapest possible shared hosting. I settled for JustHost, which popped up on many comparison sites and seemed to be good value for money, at $2.81/month including VAT.

JustHost isn’t terrible, but there were a few problems. The server ( seemed starved for memory and I was unable to work with my www.git because of it at one point. Another time I couldn’t log in over SSH for the better part of a day. Finally, on August 2, there were some major problems, with my site going up and down like a yo-yo. One of the first things I did was to point Pingdom at to get some good uptime data. I have a public status page, where you can judge for yourself.

Wanting more control, I started to look for a VPS instead, and eventually settled on DigitalOcean, based on the location (Netherlands), technology (KVM) and price ($5/month, but counted hourly). As of August 6, is hosted on a virtual machine running Debian and nginx. Having root access and doing things the hard way is great, it feels like having a wardrobe computer all over again. Time (and Pingdom) will tell if it’s robust or not, but so far I’m very happy. Also, JustHost will refund me for the remaining time, which is very good of them.

In closing, if I were to pick a Web hosting solution all over again and was not in a hurry, I would try to ignore individual reviews and claimed uptimes, and instead use Pingdom to monitor sites hosted using my candidate solutions before making a decision.

New GPG key

I’ve uploaded a new GPG key to various keyservers, fetch it manually or on the command line:

$ gpg --recv-keys 0xF75964F29DC6C210

Before creating the key, I took inspiration from Ubuntu and Christopher Wellons, arriving at this for my gpg.conf:

cert-digest-algo SHA512
default-preference-list SHA512 SHA384 SHA256 SHA224 AES256 AES192 AES CAST5 BZIP2 ZLIB ZIP Uncompressed
personal-cipher-preferences AES256 AES192 AES
personal-digest-preferences SHA512 SHA384 SHA256 SHA224
s2k-cipher-algo AES256
s2k-digest-algo SHA512
s2k-mode 3
s2k-count 65011712

The first half is in order to use the SHA-2 and AES instead of SHA-1 and CAST5, while the s2k settings are there to make brute force as expensive as possible in the event that my private key should be compromised.

I’m starting from scratch with my web of trust, so if you want to play key signing, let me know.

Chinese Diceware

I’ve been trying to come up with strong passwords since forever, and have failed to find a magic alternative to entropy. Recently, I took Diceware for a roll, but wasn’t entirely happy with passwords like “wn rare swung strop situs slept”—wn isn’t even a word, is it? I also tried the Swedish dictionary but wasn’t much happier.

How about Mandarin Chinese, written using pinyin? There are only around 400 pinyin syllables, but thousands of characters with different meanings, so I guessed that for a random sequence of syllables it should often be possible to come up with a somewhat meaningful phrase.

The kHanyuPinlu property from the Unihan database turned out to be an excellent source for character to syllable mapping, so I wrote to reverse that mapping. The output is a list of 392 pinyin syllables with example characters in traditional and simplified Chinese.

Unfortunately, 392 is not a power of 6, so using real dice to generate the numbers is a bit complicated, albeit possible. Instead I wrote, which uses as few bytes as possible from /dev/random to roll a die with an arbitrary number of sides.

Using my list and my virtual D-392, here are the first 6-syllable pinyin phrases I generated, each with a memorable (?) Chinese phrase and a rough English translation.

  • yan kai bo ren se dai—眼開撥任色帶—eyes open, poke any ribbon
  • zui ku ba ge mei xu—最酷八個沒序—the coolest eight have no order
  • ban zhai dian die keng bao—搬宅殿爹吭抱—moving villa/palace, dad says hold (this)
  • you mu sa kang xu su—有母萨扛需速—(things) carried by mother Bodhisattva need speed

A native speaker would probably be able to come up with better phrases, but I think that I could remember any of these, with 最酷八個沒序 being the easiest. If this is a representative sample, I think the scheme works.

How about the entropy? With 392 syllables, each syllable contributes log2(392) = 8.6 bits, so these 6-syllable phrases have 51.6 bits of entropy, slightly better than a completely random 8-character alphanumeric password. English Diceware has 12.9 bits of entropy per word, so to get as much entropy as with a 6-word English phrase, a 9-syllable Chinese phrase is needed. The average word and syllable length are 4.2 and 3.2 respectively, so the average phrase lengths (including spaces) would be 30.2 for English and 36.8 for Chinese. (Removing spaces blindly will lose some entropy if the pinyin becomes ambiguous.)

Feel free to use/improve my lists and scripts, and never forget: the coolest eight have no order!