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Suddenly the Dungeon collapses!! - You die...
Archive for the ‘System Administration’ Category
Best Thing Today
Wednesday, March 10th, 2010Telenor Internet Ubuntu Karmic Koala
Saturday, January 30th, 2010I got a new laptop (asus ul30a) 
and I figured I need to have internet on the go
wimax is not an option (not available) so I chose cell usb modem from Telenor
data plan is prepaid, 3 GB for two months (a new year promotion that ends tomorrow)
I thought I was getting Huawei E1550 but I ended up with Huawei E620 
that modem is not on their website (listed usb modems) nor in the manual I got with the thing
the manual talks about Huawei E1550
now why do I care so much about exact models? well because modem should run on my linux box
I saw Huawei E220 was well supported and Huawei E1550 had some glitches but could be made to work
first I used usb modem in Windows so that the autorun process can install device drivers
that’s just how it works the first time
in linux, I first installed usb-modeswitch package
lsusb wrote that it was Huawei E620 with id 12d1:1001
but after searching for that ID I found references to Huawei E169 with that same id?!
on the plus side ubuntu Network Manager Applet works great with this modem
I defined a new connection, specified my country and mobile network provider and it just worked!
Spamassassin 2010 Bug
Saturday, January 2nd, 2010it seems Spamassassin has a bug related to year 2010
the problematic rule is FH_DATE_PAST_20XX
just find 72_active.cf file and replace ‘/20[1-9][0-9]/’ to for example ‘/20[2-9][0-9]/’
now, the problem year is 2020 but by then your file will probably get overwritten by your distribution
you can put whatever number instead of 1, not just 2 and make it work longer
or simpler, edit your local.cf and set this rule to have zero score
score FH_DATE_PAST_20XX 0.0
once your distribution fixes this just remove local.cf entry
OpenSolaris Summer School @ Belgrade, Serbia
Tuesday, July 7th, 2009the school is held at the Institute Of Physics, Belgrade for the month of July, two times a week
today, Uros Nedic, the guy doing the lecture, arrived a bit late but I managed to find a beautiful park behind the institute with a great view of the Danube river
I had a nice time today
we were learning about Sun OS processes, threads, LWM, kthreads, DTrace, Zones and ZFS
Uros was great while teaching us/giving a lecture, answered all of our questions
I learned a lot
now, here are some pictures I took with my mobile phone, sorry for the bad quality
Cpanel Issues
Wednesday, May 27th, 2009I got this dedicated box to setup and I’ve found 2 problems right away
first, I couldn’t update cpanel to latest stable because one perl module, NetAddr::IP wouldn’t install
the problem was, a configure script had a malformed first line #! /bin/bash (notice the extra space after the ! character)
that got fixed
now, I have problems with cpanel license when I reboot, it says license is not valid
I have to run /usr/local/cpanel/cpkeyclt to get it fixed
I’ll report it to them but I could also easily just add it to rc.local
don’t get me wrong, I still really like cpanel but I hate issues when dealing with a new box
Dynamic DNS Iptables Firewall Script
Thursday, October 9th, 2008I’m using my computer as a development platform and I usually let people in by editing my firewall active table
but for those with dynamic ip addresses I had to figure out a different solution
so I made a small script in PHP to check for my friends dynamic ip address by looking up his dyndns.org hostname
it checks IP then goes sleeping for 5 minutes
when it detects an ip change it updates firewall by flushing my firends chain and adding a rule to let him access my webserver
this script works in my firewall iptables setup, it could work on yours but you have to be smart and figure that out for yourself, I’m not giving any guaranteess for this, use it as GPL V3 code
if you want me to help you set it up, just contact me
here’s the code:
#!/usr/bin/php
<?php
/*
use this code as GPL V3 licence says
Copyright (C) 2008, Miroslav Madzarevic, All Rights Reserved
*/
$old_ip = '';
while (1) {
sleep (300);
$host = 'friend.dyndns.org';
if (!preg_match('/^'.$host.' has address ((?:\d{1,3}\.){3}\d{1,3})$/',
exec ("/usr/bin/host $host"), $matches)) {
echo "IP problems\n";
continue;
}
$ip = $matches[1];
$ip_parts = preg_split ('/\./', $ip, -1, PREG_SPLIT_NO_EMPTY);
if (count($ip_parts) != 4) {
echo "wrong ip parts count\n";
exit;
}
$good = array();
foreach ($ip_parts as $ip_part) {
$ip_part = (int) $ip_part;
if ($ip_part < 1 or $ip_part > 254) {
echo "wrong ip part, $ip_part\n";
exit;
}
$good[] = $ip_part;
}
$new_ip = join('.', $good);
if ($old_ip != $new_ip) {
`/sbin/iptables -F friend`;
`/sbin/iptables -A friend -s $new_ip/32 -p tcp -m tcp --dport 80 -j ACCEPT`;
$old_ip = $new_ip;
}
}
?>
fastcgi mod_fcgid
Wednesday, October 1st, 2008I’ve been playing a little on my cPanel hosting trying to get maximum speed while also enforcing security at running php scripts
I first started with security running mod_suphp and while it worked fine it lacked the speed of the DSO php (mod_php)
so I read a thing or two about fastcgi and enabled it
I’m pleasantly surprised by the speed of the hosting
each user got its own persistent php application running requests (actually it’s limited to 500 php requests per php5 process by MaxRequestsPerProcess 500 directive)
I’m keeping an eye about the memory consumption but I hope I’ll be able to keep running with this setup
and while I got php running as the actuall cPanel user, apache is still running as nobody for other requests… hmmm… I’m using apache 2.2 with MPM Prefork… maybe I should try a different MPM?
C++ Hibernate Daemon
Wednesday, April 30th, 2008I use Fluxbox window manager on Ubuntu Linux where I don’t have all the bells and whistles of GNOME or KDE.
so I thought I’d make myself a daemon program that will automatically put my computer to hibernate when my laptop battery is almost empty
usually I take care that my battery doesn’t get to the red zone but this is for those few cases I forget
I wrote this small programm in C++
why c++
well because I don’t programm in c++ and I found it interesting to do so
main.cpp looks like this
so, you see the locations of the info and state file for the laptop battery, the percent at which we go to hibernation (I’ve set it to 12%), and the sleep interval before checking the battery state again (10 seconds)
I use my own hibernate script but you could use something like /usr/sbin/hibernate
you can change all of these
in the main function you can se that:
- we work only as a root user
- we daemonize (detach from the terminal and run in background)
- instantiate a worker class object
- and do our work
and what is our work? check out this picture
well we get the battery total capacity and current capacity and then we calculate the percent
if the percent is less that what I want (12%) then I want my laptop to go to hibernaton
but I also made a security check (that you can remove if you like)
that makes sure my laptop doesn’t go twice into hibernation in succession
why did I do that?
well because I parse data from some files I have no influence over
and those files can change their format anytime
so this is just a precaution
I have a simple makefile that compiles this code, copies it to /usr/local/bin/medved (medved in my language means a bear and bears hibernate ) and adds an entry to /etc/rc.local so that it starts next time you reboot your box automatically
you can also start it by hand and see how it works before the reboot
and that’s it, now I have a daemon that puts my laptop to hibernation before my battery runs dry
I’ve published the source code under GPL licence version 3
you can get source code here
NFS
Tuesday, January 8th, 2008It’s so easy to setup NFS server. I needed NFS so I could export my OGG files to my dbox.
I’m runing Ubuntu.
Here are the commands
root@warlock:/etc# apt-get install portmap nfs-kernel-server
After that, I had to edit my /etc/exports file
root@warlock:/etc# cat /etc/exports
/exports dbox(ro,sync)
And now, whenever I change the contents of /etc/exports I need to do exportfs -ra
Zabbix
Monday, December 31st, 2007Zabbix is a network monitoring solution. I used to play with Nagios but I find Zabbix a better product. Simpler to install, easier to use, better web interface.
Zabbix works in a client/server mode. Client is called an agent so on each box you want monitored you install the agent. The server gets installed either with mysql or with postgresql database support. I opted for mysql. The install was done on my laptop Ubuntu. I had some problems early on since my server didn’t see my client.
This was because of the server or client settings that I changed. Since installing both products I noticed a lot of forks/threads in the process list and I wanted to cut down the number of those by editing a config file.
Don’t do that, Zabbix doesn’t like that
Now I got 25 Zabbix instances in my process list
root@warlock:/tmp# ps aux|grep zabbix|grep -v grep|wc -l
25
Anyway, Zabbix looks nice. I can monitor everything related to how my box functions. I had to clone 2 eth0 rules (incoming and outgoing) and make it work for my wireless network. I just changed eth0 to ath0 both times after cloning.
I have to figure out how to send daily reports to my email
