There have been a couple of problems about using the devices, which I will try to document here from now on. The first thing to note is about mini-Netstumbler. Netstumbler is “a tool for Windows that facilitates detection of Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards”. In general Netstumbler needs a compatible device to be able to report noise levels. I was lucky to have an old SanDisk CompactFlash WiFi card which is able to report noise level.

I used a converter to connect the CompactFlash WiFi card to my notebook using the PCMCIA slot. Netstumbler under Windows XP was able to use this card without any other change. Below is a screenshot of Netstumbler.

Running miniNetstumbler needed one extra step. If you do not know this you may easily waste some hours. I had to to go to network settings, and add a wireless network setting with ESSID “ANY“, without encryption. Then connected to this “network” and ran miniNetstumbler. If you do not use the “ANY” network, you will see only statistics of the network you are connected to and not other networks.

I will try to post more about these later.

UPDATE: The list of compatible devices provided by NetStumbler is *not* updated. I got a Linksys WUSBGV4 through the link in www.stumbler.com/compat but it does not work with NetStumbler.

You can find good tutorials here on their website, but even after reading these you may encounter some unexpected problems. How to solve theseproblems? Always Google them use Google search engine to find the solution.

As you know, if you know lam-mpi, you should “wipe” the mp-cloud clean if you want to stop it; or if you want to restart it. It uses RSH which is sometimes not very easy to deal with. I wrote some scripts to ease the start-up and cleaning process.

The following script first pings the broadcast address and gets currently available nodes. Then updates the lamhosts file. Next uses the updated lamhosts file to wipe the network clean, and run lam-mpi again. You can optionally instruct i not to update the lamhosts file.

This is the probe script:

#!/bin/bash
#clear
RES=`ping -b -c 10 192.168.0.255 | awk ‘{print $4}’ | grep 192 | uniq | awk -F: ‘{print $1}’ | sort -n | uniq `for i in $RES; do
echo $i;
done

This one is the lam-run script, which uses the previous one:

#!/bin/bash
OPTION=”-c”;
LAMHOSTS=”/home/user01/lamhosts”export LAMRSH=”rsh”

if [ -z $1 ]; then
echo “usage: $0 {-c:update config and restart | -d: restart only}”
exit
fi;

cat > $LAMHOSTS <
EoF

if [ $1 = $OPTION ]; then
echo -e “updating lamhosts:\n”;
for i in `/bin/bash /usr/local/bin/ada/probe`; do
echo -e “$i\t user01″ >> $LAMHOSTS;
done;
fi;

echo -e “\nStopping previsou run, if any\n”
/usr/bin/lamhalt
/usr/bin/wipe $LAMHOSTS
echo “DONE”
echo -e “\nrunning lamboot”
lamboot -d $LAMHOSTS
echo “DONE”

Also, I had a copier script to copy the necessary files to all clients using rcp:

#!/bin/bashif [ -z $1 ] ||[ -z $2 ]; then
echo -e “This script lets you copy a file to every client\n”;
echo -e “usage: $0 PATH-TO-LOCAL-FILE PATH-ON-EACH-CLIENT\n”
echo -e “example: $0 /tmp/file /home/user01/remote”
exit;
fi;

for i in `/usr/local/bin/ada/probe`; do
if [ $i = "192.168.0.100" ]; then
continue;
fi;
echo “copying file to $i”
/usr/bin/rcp $1 $i:$2;
done;

These are not appealing as scripts, I know. But were quiet handy and helped us alot. I had a directory for these in /usr/local/bin/ada/, and our clients had IP addresses in 192.168.0.100/24 range. These scripts are written based on these facts. It is easy to update them for your local network, if interested.

We had some other problems that I will add here whenever I remember them, but for the moment:

• poll: protocol failure in circuit setup

if you see

poll: protocol failure in circuit setup

when you try to run a simple rsh command like

rsh 192.168.0.101 -n -d -l user01 echo $SHELL

but you can login to the remote client using

rsh 192.168.0.101

try turning off you firewall on both sides first, and then try again. If this is the case, try something like this in your firewall rules:

-A INPUT -i eth0 -j ACCEPT

where eth0 is connected to your internal network of lam nodes.

Fortunately, Babak was around to “make config” apache and make world a better place to live.

I found a forum thread with more details here.