Replacing Ubuntu with Crunchbang

With the release of Precise Pangolin, Lucid Lynx's (Netbook Remix) days on my old Asus EEE900 netbook are numbered. It wasn't clear that Precise would run well on this old hardware (Celeron, 1GB RAM, 16GB SSD, dual booting XP) and I wasn't keen on the ongoing UI simplifications in Ubuntu so I decided to switch to Crunchbang Statler. CLI holds no terror for me and I would benefit from the tons of up to date Debian packages.


The install from USB stick using unetbootin was anti-climatic. The whole process has been described here so I won't repeat that. The only hitch was when I forgot the 1GB USB stick I first tried has a weird "floppy" partition which the netbook tried to boot from. I succeeded when I used a more conventional 1GB USB stick, actually a broken USB MP3 player.


The result is a much more responsive netbook. I can even watch videos using VLC streaming over WiFi from a Samba share; this used to struggle on Lucid UNR. Mounting the Samba share was quite easy. The applications in Crunchbang may not be as integrated as on Ubuntu, but all the applications and connectivity options are there if you are willing to use the keyboard shortcuts instead of insisting on icons everywhere. It also shows how much more friendly Debian is these days when there is a bit of UI facade.


I think I will be quite happy to take the netbook on my next travels until I find a pad and BT keyboard combo that I like.

Adobe Reader oops

If you have received an update on your Linux machine for the latest Adobe Reader plugin for Firefox, then you may see a stray file of this name in one of your directories: C:\nppdf32Log\debuglog.txt (yes, with the backslashes, because backslash is legal in Unix/Linux filenames). In my case it was in ~/Documents/


From a web search this appears to be a boo-boo by Adobe programmers, releasing a package with a debug feature enabled. It doesn't seem to hurt anything, just makes people suspicious that their system has been rooted. I'm sure another Reader release will be imminent.


Sigh, I always thought they were cowboys, to observe the constant stream of security patches to Reader and Flash Player. For Reader there are alternatives like okular or evince, but Flash Player is harder to replace.

Modifying synbak to use lzop or xz for compression

For backing up a server I installed the synbak program on CentOS, partly because it was a standard package from rpmforge, and partly because it is uncomplicated to use, basically just shell scripts. I noticed that when I used gzip as the compression method, it tied up a whole CPU doing the compression. So I decided to add lzop support. It's very easy, just add these two lines to /usr/share/synbak/method/tar/tar.sh:

--- /usr/share/synbak/method/tar/tar.sh.orig    2010-06-10 05:18:14.000000000 +1000
+++ /usr/share/synbak/method/tar/tar.sh 2012-04-12 09:46:36.000000000 +1000
@@ -30,6 +30,8 @@
        tar)    backup_method_opts_default="--totals -cpf"  ; backup_name_extension="tar" ;;
        gz)     backup_method_opts_default="--totals -zcpf" ; backup_name_extension="tar.gz" ;;
        bz2)    backup_method_opts_default="--totals -jcpf" ; backup_name_extension="tar.bz2" ;;
+       lzo)    backup_method_opts_default="--use-compress-program=lzop --totals -cpf" ; backup_name_extension="tar.lzo" ;;
+       xz)     backup_method_opts_default="--use-compress-program=xz --totals -cpf" ; backup_name_extension="tar.xz" ;;
        *)      report_text extra_option_wrong && exit 1 ;;
   esac


You run it like this: synbak -s serverconfig -m tar -M lzo

I added xz support for good measure, but this is untested. Make sure that backup_method_opts in your config file doesn't have -z or the tar command will throw an error.


Naturally you must have the lzop and/or xz packages installed.


Using lzop, tar and lzop take about equal amounts of CPU time, most of the time tar was I/O bound, and backups finished faster. I also see that the memory footprint of lzop is small. The downside that is the compressed output is larger, about 31% more in my case. Decompression is supposed to be very fast, which is useful when restoring. I haven't used decompression and I hope I won't ever have to.

File AI for instant filesharing

While doing a search for cloud services to share files to a small number of recipients, I came across the interesting File AI service, which deserves to be better known, even though it's been running for a few years. It works by running a peer-to-peer Java applet in a browser on both sides. No software needs to be installed, as long as your browser supports Java.


It's very simple to use, to send a file, just go to fileai.com, click on Send and follow the instructions. You will need to click Run or Trust when the Java applet wants to run because it's unsigned. (Your recipients will also.) Then you drag and drop files you want to share into the "folder". You get a URL that you send to your recipients by email, etc. You can optionally specify a password for recipients before adding any files. You must keep the browser open until all the recipients have the file.


At the recipient end, they just click on your link, or paste it into a browser, click Run or Trust for the Java applet and the file is on the way.


Here is an blog post describing it and here is a YouTube video.


And in case you were wondering, yes it works behind firewalls.

Old netbook as a tethered Internet gateway

I had an ancient Asus EEE700 useless even as a netbook for the road. I wondered if I could turn it into an emergency gateway to my Android smartphone for when my ADSL connection goes down. It has Crunchbang Linux installed which is basically Debian. Here's what I did, for the learning experience:


First you need to disable NetworkManager. Easiest way to do this is to first install the sysv-rc-conf package, and then use its ncurses interface to shut NetworkManager down. Next you need to configure usb0 (the tethered interface) and eth0, the gateway interface by editing /etc/network/interfaces. You might want to preserve an old version of this file to restore to the default setup. Here are the stanzas used:


allow-hotplug usb0
iface usb0 inet dhcp


auto eth0
iface eth0 inet static
        address GW
        netmask 255.255.255.0

GW should be replaced by whatever gateway address is suitable for your LAN. If your ADSL router is 10.0.1.254, perhaps 10.0.1.253 is suitable.

Here are the rules to make it a NATting gateway, taken from Masquerading Made Simple. I have replaced ppp0 with usb0 everywhere:


iptables -F; iptables -t nat -F; iptables -t mangle -F
iptables -t nat -A POSTROUTING -o usb0 -j MASQUERADE
echo 1 > /proc/sys/net/ipv4/ip_forward


And to secure it:


iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A INPUT -m state --state NEW ! -i usb0 -j ACCEPT
iptables -P INPUT DROP   #only if the first two are succesful
iptables -A FORWARD -i usb0 -o usb0 -j REJECT


You could save the setup using iptables-save, like this:


iptables-save > /etc/gateway.iptables


Then make a shell script to start the gateway for convenience:


#!/bin/sh
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables-restore < /etc/gateway.iptables


Now tether the netbook to the Android smartphone. When you do ip addr, you should see that it has obtained a private address from your smartphone, and your eth0 address should be static.


Next, on your workstation change the default gateway. From a Linux command line it's


route add default gw 10.0.1.253


When you access the Internet, you should see the traffic icons on your smartphone flash. In addition if you go to a website that tells you your IP address, like whatismyipaddress.com, you should see the external address of your smartphone.


When your ADSL service comes back, delete the route with:


route del default gw


Oh yes, this setup does double NAT, since your smartphone does one NAT.

Open Source to the rescue (of Windows)

I needed to set up an XP workstation with wireless access using an old SMC USB wireless G dongle. This device is based on the Prism chipset.


The SMC drivers installed fine and detected the device. XP with all the latest updates supports WPA2. Unfortunately the ancient (2005) SMC management utility doesn't support WPA2, only WPA at best. The native wireless management service on XP, WZC was unstable and caused a crash as soon as it was started. I didn't want to weaken the AP security to WPA.


Happily I found an open source utility called wpa_supplicant, which runs on Linux, BSD, OS/X and Windows. I installed the Windows version of this, and after filling in the credentials, the wireless connection just worked over WPA2. The GUI version of the utility requires clicking on a button to launch the service. I could install the service version of the utility to start automatically at boot, but the user interaction is not onerous for this temporary setup.


Open Source rocks, again.