Small Cheese » Minimalist

How To Know When Someone Login Your Facebook Account?

Minimalist — Sat, 08 May 2010 10:19:39 +0000

You care about privacy and thus using a strong password for login to Facebook. So, you may also like to get notified when someone login your Facebook account, just in case the password accidentally leaked to third party by Trojan / keylogger infection (as a result of security software malfunction).

How to enable Facebook Account Security feature for receiving notification of suspicious login activity

1) Login to Facebook

2) Click the Account link on top-right corner and select Account Settings from the option menu

3) Click on the “Account Security” link to expand it – set the option to YES and hit the Submit button:

After turn on the Facebook Account Security option

1) When you or someone login to your Facebook account on a computer that is either never been used before for this purpose or its web browser cache has been cleared, then a new page is displayed asking user to register that computer in question before loading the News Feed or anything of your account.

2) Next, Facebook endeavours to notify / alert account owner about the incident via registered email address.

The “register computer” page forces the “bad guy” to choose either leave without access to personal information in Facebook or get Facebook to notify you about this incident via registered email (don’t ever use the same password for online accounts).

New Formula To Calculate Linux Swap Partition Size

Minimalist — Mon, 03 May 2010 16:03:51 +0000

Old school recommends the Linux swap partition should be at least 1.5 to 2 times of total memory installed. You might have no question to apply this formula on an aging server with probably only 2GB of RAM or much lesser.

But nowadays the new servers are easily built with few tens to hundreds of RAM and that means a lot of disk space will have to be allocated for swap partition if you have to apply the old formula.

So, what is the new school suggestion? Well, there is a reference of recommended swap space size made for installing RHEL 5.4 on x86/64 platform. The RHEL engineers seem have found the relationship between memory workload and swap space utilization.

However, it is not easy in practical to precisely determine memory workload before the server is installed with OS and deployed to production. Thus, they suggest a reference of recommended swap space size as follow:

At least

2GB swap space for 4GB of RAM or less.
4GB swap space for 4-16GB of RAM
8GB swap space for 16-64GB of RAM
16GB swap space for 64-256GB of RAM
32GB swap space for 256-512GB of RAM

If there is more than 1 disk drive installed in the server, you should also try to allocate the swap space to multiple disk disks for better overall performance.

If there is no dedicated recommendation made for your Linux distribution, then this reference is good for a guide. For those who are using CentOS, guess you know there is no difference between the two distributions.

What Is RHEL Installation Number?

Minimalist — Sun, 02 May 2010 12:58:12 +0000

There is an official reference of RHEL installation number, which is also known as subscription number or registration number.

Brief of the RHEL installation number:

1) RHEL installation number is used to determine what packages are entitled for the user’s subscription and is used by rhn_register to automatically register the system to the right RHN channels.

RHH, short for Red Hat Network, served as an official depository of latest packages and patches for Red Hat Enterprise Linux. RHN is similar to Microsoft Update but RHN includes additional features than simply provide system update.

2) Unlike software license like Windows 7 product key and activation key, RHEL installation number is not bind to the hardware. Indeed, RHEL installation number is unique per order / subscription. So, it is possible to install RHEL 5 on multiple servers with the same installation number.

3) If you choose to skip entering the installation number during RHEL installation, then only the core operating system components will be installed (sort of tiny RHEL installation with minimal functionality). However, you can install additional packages at post-installation if you register the system to RHN via the rhn_register command. The installation number is not needed when registering to RHN if the subscription has been activated.

How To Recover RHEL 5 Installation Number If You Lost It?

Minimalist — Sun, 02 May 2010 12:03:39 +0000

While preparing a plan to reinstall Red Hat Enterprise Linux 5.2, you find out the RHEL installation number is missing and wonder is there a way to recover or get back the installation number from the installed system?

Well, the answer is yes as you wish, with reference to RHEL 5 Installation Notes.

Starting with RHEL 5, Redhat introduces RHEL subscription number, a.k.a. installation number or registration number, to determine what features or packages are entitled for user’s subscription.

Two simple steps to recover RHEL 5 installation number from installed system

1) Login as root,

2) Uses the cat command to display the installation number that kept in the plain text file:

cat /etc/sysconfig/rhn/install-num

If there is this install-num, there you will get back the “precious” RHEL installation number.

What if you have formatted the RHEL 5?

Well, that maybe too bad or maybe not.

Normally, branded server like HP, DELL, etc, does provide recovery CD for restoring the server to the state as it was delivered to client. If the purchased server should come with licensed OS and software, those components should have also been included in the recovery CD.

If you have such recovery CD, then reinstall the server with this recovery CD and try to see if there is a copy of install-num file.

What Is Reader_sl.exe? Can It Be Disabled?

Minimalist — Thu, 22 Apr 2010 10:16:16 +0000

As shown in Windows 7 System Configuration, the Reader_sl.exe starts running automatically after Windows boots up:

With reference to The Adobe Synchronizer, this reader_sl.exe should be the Adobe Speed Launcher program.

According to Adobe Help Resource Center, Speed Launcher is installed by Adobe Reader into the Windows startup group. The only function of Speed Launcher, as its name implies, is to shorten the time needed to start Adobe Reader.

Question: Is it safe to disable reader_sl.exe?

Answer: No harm to disable it. If you have an old computer system and do feel the slow responding of Adobe Reader after disable it, then just turn it on again.

Steps to disable or turn on Speed Launcher

Using my Windows 7 as a guide:

1) Click Start button, type msconfig.exe and press ENTER key to bring up the System Configuration dialog box (as the one shown in screenshot above).

2) Go to Startup tab, locate the Reader_sl.exe in Command column, untick the checkbox of it and click OK button to complete. (You may defer system restart by select “Exit without restart” button in the pop-up message box.)

To turn on the disabled startup item again, in this case the Speed Launcher, just tick its check box and click OK button.

Where Is Google Cache? How To Use Google Cache?

Minimalist — Wed, 21 Apr 2010 08:17:32 +0000

Very often I heard people asked this question: What is the URL or web address of Google Cache service? Well, don’t laugh, nobody born to know everything in day 1.

Unlike Google Translate, there is no such Google Cache URL, at least for now. Google Cache is one of the many Google Web Search functions or features that have no dedicated URL to refer.

To use Google Cache:

1) Just go to Google Web Search text box and add the keyword cache: in front of the URL that you would like to see:

2) There is this “cached” link in each of the Google Web Search results, except for those web pages that do not allow Google Web Search to cache or snapshot on them. If there is this “Cached” link, just click that will do:

With reference to Google Webmaster Tools Help on Remove a page or site from Google’s search results, a web page will not be available in Google Cache database if it is not visible to search engine crawler (a.k.a. web spider).

3) In Google Chrome web browser, just use its Address bar as Google Web Search text box:

Google Cache VS Google Translate: Which One To Use?

Minimalist — Wed, 21 Apr 2010 07:40:19 +0000

Most people know, except novice, that Google Cache and Google Translate can be used to browse some Internet contents that are not available explicitly or directly (e.g. blocked or filtered by firewall or proxy server).

Now, how many people know which of these two services is best to view hidden contents behind the firewall / proxy server? In other words, when to use Google Cache or Google Translate?

This trick is only applicable if the firewall or proxy server doesn’t filter Google domain or block contents by scanning keywords in URL.

Google Translate

If you want to view the most latest update in a web page that filtered or blocked by firewall / proxy server, use Google Translate service (go to the “Translate a web page” section).

Can Google Translate works if the web page is in English? Yes, it works, at least for now.

Regardless what language is specified in the “From” option drop box, as long as the “To” option is set to English, the English web page is presented as it, just like this:

Google Cache

If you want to take a QUICK peek of the web page content that blocked by firewall / proxy server AND not bother about LATEST content update (e.g. user-generated comments) as well as multimedia files like image, flash object, etc, THEN use Google Cache with “Text-only version”:

1) Go to Google Web Search text box and prefix cache: to the URL of web page that you would like to see:

For those who are using Google Chrome web browser, just use the Address bar as Google Web Search text box:

2) Some of web pages take long time to load, even in the Google Cache. To speed it up, click the “Text-Only version” link (as shown in the above screenshot).