Lars Wirzenius: System administration, 2004


Friday, October 22, 2004

System administration: Image linking, again

After thinking about what Erich Schubert and Joey Hess had to say about preventing image linking, I decided to turn off my Referer prevention. It's too much work for me to get it right in all situations.

Wednesday, October 20, 2004

System administration: Zero gigabyte USB hard disk

I bought a Transcend StoreJet zero gigabyte USB 2.0 hard disk today. Actually, it is just at wrapper for 2.5 inch laptop hard disks that talks USB to the host computer. I put in the hard disk of my old, broken laptop (Igor) and now I have a 20 gigabyte portable hard disk, which I named "Luggage". Not bad, for 31 euros.

Installing the thing went very well, I only had a minor problem: the hard disk had an adapter for its IDE connector that made it incompatible with the StoreJet's connector. Removing the adaptor made the two compatible and after that, it was all plug and play.

I have my laptop configured so that udev creates /dev/luggage and the disk is user-mountable as /media/luggage (using vfat, since I expect to exchange files with Windows using friends). I find udev so much fun I suspect I'm silly.

Friday, October 08, 2004

System administration: Preventing img linking, part 2

Erich Schubert gives some further advice on img linking. I hadn't thought of the img links I put into my RSS feed. Will have to think about that; this would be easier to solve if I knew all the places where my log is aggregated. Can't say I much care about "privacy proxies" that break Referers, however.

Joey Hess also comments and doesn't think it reasonable practise. I understand his point, and I don't disagree much. The reason I decided to block img linking, if I can, is that via my Referer log I found people using portraits I've taken of friends and others on various web sites. I don't really care about the copyright issue here, but some of those uses were potentially offensive to me or the people in the portraits. That is, the photos were being shown with img on web pages where the surrounding context was not-nice. With an a link, the context would not have been there.

I'd rather prevent my photos from being used on other sites than stop putting up photos at all. I might find a better way to do this than mucking about with Referers, however, since it is not really a very effective method.

Thursday, October 07, 2004

System administration: Preventing img linking

I got tired of people linking to my photos with the img element, so I configured Apache for, my personal domain, to not allow viewing of images if there is a Referer header that is not from my pages. Instructions from

SetEnvIfNoCase Referer "^http://liw\.iki\.fi/" local_ref=1
SetEnvIfNoCase Referer "^$" local_ref=1
<FilesMatch "\.(gif|jpg|png)">
Order Allow,Deny
Allow from env=local_ref

Monday, September 27, 2004

System administration: TCP window scaling workaround

I had a bit of trouble reaching a web site and this turned out to be a known problem related to TCP window scaling and broken routers. Linux Weekly News reports a workaround:

echo 0 > /proc/sys/net/ipv4/tcp_default_win_scale

This is just a workaround; the fix is to fix or replace the broken routers.

Monday, September 20, 2004

System administration: Plextor PX-712A DVD burner

I bought a Plextor PX-712A DVD burner (single layer, pretty much all formats) today and installed it on my scratch computer. There were absolutely no problems in installing it, either the hardware or the software. I've now used Linux kernel 2.6.8 and dvd+rw-tools for burning and everything worked the first time. I could not ask for a simpler installation. Happy now.

Wednesday, September 08, 2004

System administration: UTF-8 transition completish, except for netnews

I have now converted all my filenames (using convmv and data (using isutf8 and my editor) to UTF-8. I haven't had to configure any of my applications to use it specially, they either honor locale settings or were already configured to use UTF-8 when talking to the Internet.

The only real casualty seems to be slrn: it seems unable to live in a UTF-8 environment in any useful way, unless you stick to ASCII-only newsgroups. I experimented with a couple of other news readers, but they seemed to be unusable as well. Pan is weird and wants me to download messages, which is a strange concept for news. I don't want to be bothered about when the news reader fetches the article headers and when it fetches bodies and what not. That's all uninteresting detail to me; slrn deal with this fine. The Pan user interface is also cluttered and full of little buttons that do similar but different things, but are hard to distinguish.

Mozilla Thunderbird let me configure a news account and then proceeded to eat up all my CPU and memory. Unimpressive.

Given that Usenet is at best a distraction to me, I don't want to invest a lot of time in finding a news reader. In fact, I might be best off with abandoning Usenet altogether.

Sunday, September 05, 2004

System administration: Laptop back from repairs, re-installed

I got my laptop back from repairs on Friday. All the hardware problems I had with it are fixed. Even the optical drive. And everything was under warranty! Whee! This is so perfect. Thank you Acer Finland.

I re-installed Debian on the laptop, and wrote some installation notes about it.

Sunday, August 29, 2004

System administration: Laptop breaking down

My laptop seems to be breaking down slowly. First, the catch on the lock stopped working. Then, the optical drive. Now the touchpad is becoming worse almost every day. I've set up a scratch computer and have moved my stuff there and on Monday I'm sending in my laptop for repairs. Hopefully this won't ruin me. I'm writing this entry on the scratch computer. I will hopefully be able to work with this, but it might be that I won't be doing very much computer stuff before I get my laptop back. We'll see. If nothing else, sitting at my desk is much less comfortable than sitting in an armchair with my laptop.

Friday, July 23, 2004

System administration: Victory over the printer

Scott James Remnant advised me on cleaning the print head and someone else that it may have to be done many times. After more than ten times, the printer would finally print. Happy now.

Thursday, July 22, 2004

System administration: Printer trouble

I hate printers. My Epson Stylus Photo 890 decided that it did not like the fact that I hadn't used it for many months. It refuses to print all colors consistently and some of the nozzles in the print head seem to be blocked. I'll have to figure out a way to clean it. On the other hand, I'm beginning to think that my life would be massively better if I didn't have a printer at all and used on-line printing services or found a friend who would print things for me. Possibly that same friend could edit my pictures so that colors are corrected and the right amount of sharpening is applied and so on. In my dreams...

Wednesday, July 21, 2004

System administration: Laptop optical drive broke

The optical drive (DVD-ROM and CD-RW) in my laptop broke down a couple of weeks ago, well after warranty had ended. I've been looking for a replacement drive, and they don't seem to be available, at least not in any of the online stores I know of. Today, I finally took the ultimate step and called the store that had sold me the laptop. The result: it is possible to buy a new optical drive, at prices that start at well over 200 euros, plus I'd also have to pay for getting it installed. The laptop does not have a "bay" that would make it easy to switch the drive. Instead, the entire laptop needs to be dismantled for the drives to be swapped. I don't want to pay that much. I'll have to live without an optical drive, therefore, and use a desktop or server machine for my CD and DVD needs. Bugger.

I could buy an external, USB drive, but that would be extra baggage to carry. I don't think it's worth it.

Saturday, July 17, 2004

System administration: Wireless network at home

I now have a wireless network at home. Whee.

A couple of weeks ago, a friend gave me a Lucent Wavepoint-II access point for free, and this prompted me to buy a wireless LAN PCMCIA card for my laptop. After some investigation, it seemed that cards based on the Prism54 chipset were a good choice, and I bought a 3com OfficeConnect Wireless 11g PC Card. It has a driver in the Linux 2.6.5 kernel, which is free and everything, except it requires an external file containing the firmware for the card. The Linux driver loads the file to the card upon insertion into the PCMCIA slot. The firmware file is available from and needs to be copied to /usr/lib/hotplug/firmware/isl3890. I also needed to add iface eth1 inet dhcp to my /etc/network/interfaces file. After this, with Debian unstable, hotplug and other things take care of everything automatically.

Well, almost. It turned out that the access point I got was formerly used in encrypted mode and there seemed to be no easy way to reset this behavior. Luckily, after a few days of intermittent tweaking and cursing, liiwi offered to swap his access point for mine. He's a professional sysadmin and knows how to get hardware to do his bidding, unlike me. The new access point worked like a charm the first time I plugged it into the correct Ethernet socket.

The wireless network is only 802.11b, or 11 Mbit/s, since the access point is old. It is, however, quite fast enough except for large file transfers within my home, and for those the 100 Mbit/s cable is also tardy. The PCMCIA card is 802.11g, or 54 Mbit/s, however, so if I decide to upgrade one day, I'll only need a new access point.

Having a wireless network is fun, although I must admit it isn't all that useful, as long as I stay in my chair. However, even sitting in this chair, as I am now, having one fewer cable to worry about it nice. Friends with laptops who visit me in the future will also have Internet access more easily in the future.

In fact, I'm going to keep the access point open for access for everyone in my neighborhood (properly firewalled, of course). Now that I have a wireless card, I find myself wishing for open access points in cafes and elsewhere so that I can surf or check e-mail. There are lots of hotspots in Helsinki, but they seem to be mostly commercial, costing 15 euros per day or so, whereas I'd only need a few minutes or perhaps an hour, and paying 15 euros for that is excessively costly.

Friday, May 28, 2004

System administration: Sic transit discus mundi

Some time yesterday morning my firewall machine at home broke both of its hard disks, an old IBM 30 gigabyte Deskstar and a brand new 120 gigabyte Maxtor. That was not the start of a fun day. Luckily, I could afford a new hard disk and installing a firewall machine from scratch using the new Debian installer was simplicity itself.

If I had had a microphone, I could have recorded the sounds the hard disks made. They were disturbing to say the least, and it might be educational for other people to hear broken hard disks. I haven't heard them very often myself. I think IBM used to have a web page with sounds of broken hard disks, but I can't find it now.

Sunday, April 11, 2004

System administration: GNOME 2.6 and Galeon anti-aliased fonts

I was feeling adventurous, and decided to upgrade GNOME 2.6 from Debian experimental. The dependencies are somewhat broken, so not all packages are installable, but other than that the only problem is that gpdf seems to not work at the moment for me. Not sure why, though.

I also got anti-aliased fonts to work with Galeon. Rob Weir told me on IRC that mozilla-xft needed to be installed for that. Now Galeon looks as pretty as Mozilla Firefox and I have lost all interest to switch.

Thursday, February 26, 2004

System administration: Laptop screen acting up

The screen on my laptop is developing a habit of occasionally having irregular vertical stripes. Then, after an hour or a few, they disappear. They aren't visible in white or black areas and most of my windows have white backgrounds. Thus, I can't be sure exactly how often this happens.

I guess I'll have to take the laptop in for repairs. Warranty hasn't expired yet, and hopefully covers this. It's likely to take a week at least, however, and I don't know what I'll do without a computer in the mean time.