Admins eHow SysAdmin Tips & Tricks

March 19, 2012

Simple Timer Utility

Filed under: General — Tags: , , , , — admin @ 6:15 pm

This is another utility which I wrote for myself use, it is a simple countdown timer which beeps when it reaches zero.
You can download it here : Timer

March 11, 2012

Realtime mouse position monitor tool

Filed under: Windows — Tags: , , , , , , — admin @ 5:26 pm

Sometimes very simple tools can not be found on Internet, for a project I needed to monitor mouse coordinates in real time, but I couldnt find anything useful on Internet so I wrote a small utility which displays mouse position (X,Y) on screen. It needs .net framework to be installed on your computer to work.
You can download it here : MousePos

February 26, 2012

How to update Adaptec raid driver on Centos & RHEL5

Filed under: CentOS,General — Tags: , , , , , , , — admin @ 6:51 pm

Download the driver RPMs from adaptec website, as I have 5805z controller, I downloaded the drivers from here :

http://www.adaptec.com/en-us/support/raid/sas_raid/sas-5805z
http://www.adaptec.com/en-us/downloads/rh/rhel_5/productid=sas-5805z&dn=adaptec+raid+5805z.html

You will get a file like this :

aacraid_linux_rpms_v1.1.7-28700.tgz

unpack it :

tar zxvf aacraid_linux_rpms_v1.1.7-28700.tgz

to get :

aacraid-1.1.7-28700.rpm

install rpm :

rpm -ivh --force aacraid-1.1.7-28700.rpm

it will only extract the files to /opt/Adaptec/aacraid :

cd /opt/Adaptec/aacraid
mkdir mods
mv aacraid_prebuilt.tgz mods
cd mods
tar zxvf aacraid_prebuilt.tgz
rm *.tgz

now you have prebuilt module for different kernels, copy the appropriate kernel module to aacraid.ko path, a command like :

cp aacraid-2.6.18-238.el5xen-x86_64 /lib/modules/2.6.18-274.18.1.el5xen/kernel/drivers/scsi/aacraid/aacraid.ko

if you have locate package installed, you can easy find all aacraid.ko files :

locate aacraid.ko | xargs -n1 modinfo | grep vers

when it is complete, reboot the server.

January 11, 2012

Fix nginx 502 Bad Gateway error

Filed under: General — Tags: , , , , — admin @ 11:01 am

Today I was getting “502 Bad Gateway” on a Glype proxy installation , after digging into the problem I found out it is a problem of nginx fastcgi buffers , here is how to fix it :
open /etc/nginx/nginx.conf
add the following lines into http section :

fastcgi_buffers 8 16k;
fastcgi_buffer_size 32k;

you config should look like this :

http {
.
.
fastcgi_buffers 8 16k;
fastcgi_buffer_size 32k;
.
.
}

restart nginx and fastcgi.

December 16, 2011

Linux Delete Empty Directories (Folders)

Filed under: CentOS,Debian,General,linux — Tags: , , , , , , — admin @ 6:01 am

As simple as one single command :

find -type d -empty -delete

October 5, 2011

4 Oct 2011, Bad day for iSheeps

Filed under: Android,Apple — Tags: , , , , — admin @ 8:21 pm

No doubt, 4th Oct 2011 has been a very bad day for iSheeps, their beloved fruit company left them with a minor upgraded phone after 16 months of waiting and frustration. no wonder why Steve Jobs left the company just a few weeks before new iPhone 4S announcement, he decided to leave the company in glory days. the legend will stay the legend. lambs are to be slaughtered.
I know many iSheeps have decided to leave iSheep camp and join the Android revolution. that’s a wise decision friends 🙂 welcome to superiority and excellence.
I just found something interesting. compare the following stats , first one belongs to 2009, second one to 2011 :
2009 :

2011:

As you can see in almost two years Apple has hardly kept its market share and has only grown from %25 to %27. it has happened during the golden age of iPhone 4 ! while Google market share has grown from 5% to 42% ! now you can guess what would happen with current weak embarrassing iPhone 4S ! and this superiority and excellency of Android phones now. I even expect a minus Point Change for Apple market share in next reports.
And I expect some iSheeps send apology letters to me if Google Point Change beats Apple. We will see that happen 😀

September 26, 2011

Gateway on a different subnet on Linux

Filed under: Debian,General,linux — Tags: , , , , , — admin @ 7:50 am

Theoretically host IP and gateway should be on the same IP subnet. but there are some situations where host IP and gateway subnet are on different subnets. like my situation today. I was assigned two additional IPs for my server by my Data-center, but IPs were from a different subnet compared to server main IP. these IPs will work if you set them as additional IPs. but I needed them to create two new VPS’s on my server with bridged network interface. in this situation additional IPs should serve as main IP address and there is no gateway on same subnet available.
So here are the assumptions :

a.b.c.d is the host IP
e.f.g.h is the gateway IP
a.b.c.d & e.f.g.h are on different subnets.

by default if you try to set gateway by following command :

route add default gw e.f.g.h

you will get this error :

SIOCADDRT: No such process

the trick is simple , first add a route to default gateway itself and then set the default gateway , like this :

route add e.f.g.h/32 dev eth0
route add default gw e.f.g.h

remember you may need to change eth0 to your device name , it may be eth1 or wlan0 or anything.

How to make these route changes persistent ?

For Debian/Ubuntu :
Add the following lines to /etc/network/interfaces :

post-up route add e.f.g.h/32 dev eth0
post-up route add default gw e.f.g.h

September 19, 2011

Steve Jobs’ 2005 Stanford Commencement Address – Must See

Filed under: Apple,General — Tags: , , — admin @ 8:25 pm

If you read my blog , you will know that I am not a fan of Apple. In fact I fight against its dominance and its policies.but I really admire this man, Steve Jobs. He deserves what he has acquired.
I recommend everyone to listen to this speech very carefully several times and make use of advises of this man. What he says and recommends in life is very true and useful.

Watch here :
Steve Jobs' 2005 Stanford Commencement Address

The text of speech :
‘You’ve got to find what you love,’ Jobs says

September 14, 2011

An analysis of recent security breach to DigiNotar and Man-In-The-Middle attack to Iranian users

Filed under: General,Security — Tags: , , , , , , , — admin @ 9:23 am

As I have received several requests from Iranian readers of my blog, I have done some analysis on recent DigiNotar security breach and MITM attack to Iranian users.
This analysis is based on Fox-IT interim report of breach. You can download the complete report in PDF Format from the following link :
http://www.adminsehow.com/wp-content/uploads/2011/09/rapport-fox-it-operation-black-tulip-v1-0.pdf

What is MITM attack and how to prevent it ?
MITM stands for Man-In-The-Middle. it simply means someone stands between you and destination and intercepts or modifies your communication. it is quite easy when communication is not encrypted.
SSL protocol is originally invented to address this issue. The idea is that a trusted Authority (CA) authenticates the identity of destination and by using some cryptography protocols your connection to authentic destination becomes encrypted and impossible to intercept or modify.
It has been shown that the cryptography methods like AES or RC4 which are employed to encrypt the data are quite effective and very hard to crack. so the easier solution is to attack the base of trust model, the trusted authorities (CA). In this kind of attacks, hackers break into CA systems and forge valid certificates for themselves so they can impersonate themselves as authentic destinations and intercept the data. this kind of attack is used in both recent incidents, Commodo and DigiNotar.
Although the protocol is almost safe itself, unfortunately many of these CAs are vulnerable themselves making the whole process vulnerable.
The FOX-IT report indicates the DigiNotar systems were using Windows (Which is vulnerable in nature) and passwords has been crackable through brute-force attack. (More on this later)

To understand it better, I have created a diagram of recent MITM attack to Iranian users with the goal of intercepting communications between them and Google. the attackers have been able to gain access to Google accounts of users through this attack :

This diagram is self-explanatory. The attacker in middle impersonates itself as Google and establishes a secure connection to the user which is signed by DigiNotar CA. Although the connection is still secure, but users have a secure connection to the attacker, not real Google. so attacker has access to all information sent by user, including username, passwords, cookies and etc.
(more…)

September 12, 2011

The Start of the End for Apple iPhone

Filed under: Android,Apple,iPhone — Tags: , , — admin @ 7:37 am

It seems the start of the End of Apple iPhone has begun. After few years of fruit style glory and ripping off the the customers. Our beloved open source Android is going to put an end to it.
The signs are very clear, Apple does not introduce its new iPhone based on its custom. seems fruit company has nothing significant to offer so decides to offer nothing. if you don’t play , you won’t lose. iSheeps becomes depressed and speculate the new iPhone will be released in September or October. Apple prefers to stay quiet as always based on its marketing strategy. they try to keep the iSheeps fed and excited. so they can be ripped off later.
The anticipated date for releasing iPhone 5 is closing , Steve Jobs steps down as CEO. leaving the fruit company in glory and as a hero. others are to be blamed later.
September comes, still no sign of iPhone 5. this phone has become obsolete before its release. its rival Samsung Galaxy S II is equipped with a Dual core 1.2Ghz CPU. at the best scenario iPhone 5 will be equipped with a A5 CPU made by Samsung with a clock of 1Ghz ! yet more to come, Samsung announces its next dual core 1.5Ghz smart phone will be released in next quarter. Apple is almost a year behind now. Google announces the Android based Nexus Prime will be released very soon. Apple is completely knocked out now, unable to compete in the field, sends its legion of lawyers to war.
3 major US operators Sprint, Verizon and AT&T desperate of Apple actions, decide to offer iPhone 5 rival Samsung Galaxy SII.
Statistics start to leak from research companies. Apple is not only losing the in field but also loses market share very fast.

The stats are very clear , by July 2011, Android is dominating the US market share by 42% compared to 27% Apple. the stats should have become worse for Apple by now.
If you are an iSheep reading this article , I recommend you to turn on your brain and start using it. The start of The End of iPhone has begun and clock is ticking.
Join the wave NOW ! Confess to your Sins and promise you will NEVER ripped off again by fruit company. You will be sent to Android heaven.

Edit : Seems I have had high hopes for iSheeps , there is no way to save them ! here is a response from an iSheep :

Oh I am deeply impressed 🙁
I confess to all my sins :(( I was innocent but one day when i was sick, a bad doc at hospital told me an Apple a day keeps the doctor away and involved me to this Fu… fruit lovers wave 🙁
I declare that I would not trust that doc. I’m regret and i want to apply for that anti fruit wave which you mentioned on your blog.
I give you my word that I will never ever let that fruit company to ripoff me again.
So i won’t buy any fruit company product anymore, down with apple , down with peach , down with Kivi , down with pineapple and banana. (Except watermelon which i’m in love with it, Sorry!)
Long live Pepsi and that anti fruit wave.

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