Global Networks

Earthquake and tsunami reports

An impressive 8.8 earthquake on Chile causes the Pacific tsunami warning system.

This is a very pro-active site:
http://wcatwc.arh.noaa.gov/index.html

The details here:
http://www.prh.noaa.gov/ptwc/?region=1&id=pacific.2010.02.27.234803

Labels: earthquake

Crontab examples

Crontab is a text table, per user, used by crond to launch cron jobs.
A cron job is a task written in a line of a crontab, that runs on a specific time of day / week / month.
Other crontabs can be used always by the root/cron-default-user, like the ones at:

/etc/cron.d/
/etc/cron.daily/
/etc/cron.hourly/
/etc/cron.monthly/
/etc/cron.weekly/

On RedHat, for instance, a typical setting for a monthly run is:

/etc/cron.monthly/slocate.cron

In this case slocate.cron is a script file that has:

#!/bin/sh
renice +19 -p $$ >/dev/null 2>&1
/usr/bin/updatedb -f "nfs,smbfs,ncpfs,proc,devpts" \
-e "/tmp,/var/tmp,/usr/tmp,/afs,/net"

This will allow 'locate' database (typically at /var/lib/slocate/slocate.db) to be updated.
(Try locate my_filename_or_partial_filename, and you will understand what this is.)

Now back to cron jobs, per user. An example of a crontab:

[henrique@fuji poa_20081129]$ crontab -l
# DO NOT EDIT THIS FILE - edit the master and reinstall.
# (/tmp/crontab.2736 installed on Sat Nov 29 13:36:30 2008)
# (Cron version -- $Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp $)
MAILTO=""
EMAILTO=""

#30 23 * * * /home/henrique/yprog/scripting/linux_etc/cp_inx.sh
#*/5 * * * * /home/henrique/tiny/proxies.sh 1>/dev/null 2>/dev/null
#30 22 * * * /home/henrique/yprog/scripting/robot_g/robot_3pic3.sh &
#*/5 * * * * /usr/local/bin/gcntpaserver vmsvcd
55 */4 * * * /home/henrique/yprog/scripting/linux_etc/postoffice_freesco_analyst.sh

The first three lines are comments, to remember the file shown is temporary.
Then MAILTO="" or EMAILTO="" are suited to avoid mails if one of the cron job dumps output to stderr.
The first four crons are commented, thus are not ran.
The last cron says the script '...analyst.sh' is ran every four hours, at HH:55, i.e. runs at 0:55, 4:55, 8:55, 12:55, 16:55, and 20:55.

VMware pictures

Ubuntu running in a plain VM-player.
Usually Ubuntu appliances have no password, but you can use one.
See the picture below.

Linux logos

A great picture about Linux.

Freesco is a little OS that fits in a floppy. Logo at home...

Ubuntu and Kanotix on VMware

Kanotix is the nice variant of known Knoppix, a nice Linux variant that only requires one single CD to boot. Latest versions of Knoppix are quite attractive, and they are based on a single DVD.

Personally I have sticked with the latest version of Knoppix for CD, which is version 3.9, largely stable and useful. It's really great for newbies at Linux, but can be of use for rescue for advanced Linux users, like myself. ;)

I was saying, Kanotix, is the Knoppix version installed into the hard-disk, which is 99% equal to Knoppix, except it works faster -- for obvious reasons (no CD-ROM reading or scrubbing).

I have installed Kanotix in a VMware server box, which has a great look and feel for my six year old daughter.

Here the installation steps, look & feel, it's great, isn't it?

Finally running:

I have performed some tweaks to ease my life:
* ssh runs by default, unlike Knoppix / Kanotix defaults;
* root has also a password, unlike Knoppix / Kanotix defaults;
* guest user created, for childs, password is a really hard hashed word... just "guest".

Ubuntu on VMware

Ubuntu is a really nice choice when using VMware, especially suited for newbies on Linux.
It is intuitive.
Though uses Gnome by default it can be quite easy to work once installed.

In the picture you can see Ubuntu Edgy (6.10) upgrading their packages in a one step click.

Side information:
Recent Ubuntu installers (i386), portuguese locations

darkstar is the co-name for IST server:
http://darkstar.ist.utl.pt/ubuntu/releases/7.10/ubuntu-7.10-server-i386.iso

Another portuguese nice location:
http://neacm.fe.up.pt/pub/ubuntu-releases/7.10/
it's Gutsy:
http://neacm.fe.up.pt/pub/ubuntu-releases/gutsy/

netpack-gpack (gpackcount)

Sniffing your own network, from internet to your home / office intranet, using a Linux router...can be easily achieved with a Freesco-box, or some Linux distro, and gpackcount, a small application that shows all traffic through your networks.

gpackcount is included in the netpack-gpack, just released.
Sources are freely available, and packaged binaries are expected soon. Refer here to the release article: netpack.blogspot.com/2007/12/netpack-gpack-is-released.html

Refer here (left-side picture) for a snapshot for my own sniffing of network between a Freesco-box and another server. Some basic commands are shown to minimize traffic.

Note domains are cached within gpackcount to minimize additional traffic through domain port (UDP, 53).

Here's another snapshot of the result of brief minutes of sniffing.

You can see *.google.com, because by the time I was writting this article, gpackcount was sniffing traffic (and www.blogger.com domain belongs to all mighty Google.)

There are no fancy rules to gather traffic for a group of ports, or anything like that. The output is typically the byte comprehensive streaming, and a plain text report at the end.

Listening music on a PC

In this article I praise some of the best tools for hearing music on a PC:

Quintessential player (aka Qcdplayer)
http://www.quinnware.com/
VUPlayer
http://www.vuplayer.com/

The first has a better look, lots of functions, easy-to-use.
The second, by James Chapman, has a straight forward visual look, but also nice functions: I highlight the capability of fading between tracks, better play-lists (so called vpl, VUPlayer play list), and an easy to use local and remote / cached cddb database - text mode, which is great for browsing / grep.