Category Archives: CentOS

Theory About Bulk Emails

Common Question among Friends…
How many email I can send through my mail server?

Well, Everything depend on your server including “EMail Server”…. we can say all depend on our budget :)

The number of emails you can send depend on… “Server’s Bandwidth”, “Size of Messages”, “Expected number of failures”…..

Number of seconds to send all data = Total amount of data to send / Bandwidth per second

Some Hosting packages (# emails depend on server):
Budget Shared Hosting Plans – 100 emails per hour
Unlimited Hosting Plans – 100 emails per hour
Advanced Shared Hosting Plans – 250 emails per hour
Professional Shared Hosting Plans – 500 emails per hour
Resellers – All Reseller Servers have a 500 email per hour
Semi-Dedicated Servers – 5000 emails per hour
Cloud VDS – No Limit
Dedicated Servers – No Limit
Enterprise Cloud Servers – No Limit


PowerMTA – This is a product from specifically a mail delivery backend that handles email delivery, inbound bounces & replies, reporting & load balancing.

Read Full Article here



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Self-Scaling hosting environment utilizing Amazon’s EC2


How to Setup Elastic Load Balancing on AWS


How to clean malware from website?

Malware, short for malicious software, is a software designed to secretly access a computer system without the owner’s informed consent. The expression is a general term used by computer professionals to mean a variety of forms of hostile, intrusive, or annoying software or program code.

You have seen above warning many times when you want to browse website using web browsers. This is the warning from search engine bots like Google for website is affected from malwares or viruses. If you still want to access website, it can affect your system or system resources.

Most of times websites are hacked or unauthorized accessed from hackers or cross-site scripting (XSS) or cross-site request forgeries (CSRF).

There may be lot of “holes” in website security that invite hackers to play their game.

The possible HOLES may be:
1. File/Folder permissions
2. Poor authentication for application
3. Cross-Site Scripting
4. Cross-Site Request Forgeries
5. Anti-Virus Software
6. File formats
7. Network “Firewalls/Filters”
8. Shell access & Logs

Please check some link to make web application secure and safe 😉

You can review online Virus & Threat Scanner for cleaning malwares & viruses. These softwares are designed to run on your web server and scan your public web files for malicious code.

Google Safe Browsing Tool

Norton Safe Web

You can search for more tools like…
Security Pro | SiteMonitor | IP trap | htaccess | AntiXSS | Check Permissions | KISS FileSafe

If you are running PHP website under Apache & MySQL, make sure file and folder should not be access public. You have to check PHP function’s security for more secure access.

PHP Functions may be used in hacking:
1. file_get_contents()
2. base64_decode()
3. eval()
4. exec()
5. preg_match()
6. gzuncompress()
7. urldecode()
8. error_reporting()
9. shell_exec()
10. setcookie()
11. chmod()
12. is_writable()
13. move_uploaded_file() and copy()

The above functions can be used by hackers to write malicious code to your files. The malicious code executed using eval() that will execute every run of website. So, disable eval(), file_put_contents(), file_get_contents(), exec() etc. You can check safe_mode in php.ini for disabling shell access 😉

Most of the time websites are hacked using file_get_contents(), eval(base64_decode()), urldecode(), include() or iframes.

You can search infected file on web server “/var/www/” using below command:

# grep -iR ‘eval(base64_decode(‘ /web-root
# grep -iR ‘ # grep -iR ‘urldecode(‘ /web-root
# grep -iR ‘file_get_contents(‘ /web-root
# grep -iR ‘exec(‘ /web-root

As soon as infection found, you have to backup all application running on web server, now you have to remove infected files manually or using scanner.
Now all up to you how you can manage your web server more securely…

I’ve found that luck is quite predictable. If you want more luck, take more chances. Be more active. Show up more often. 😀


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Recursive Replace in Files Folders

Hello Friends,
Some time we want to change branding of web based softwares. Open source web based software have GNU License. We can modify the code and launch versions.
We can use PERL (Perl is a highly capable, feature-rich programming language with over 22 years of development.)
Here are some basic steps to Recursive Replace Rename Files, Variables, Folder Name etc.
Let you have a project in folder "/root/svnlabs"
To replace search string in all filename and foldernames recursively

# chmod a+x ./

# perl -m g 'search_text' 'replace_text'

# chmod a+x ./

# perl -m g 'Search' 'Replace'

# grep -iRl 'Search' /root/svnlabs  (Now search in your project)

If you would hit the mark, you must aim a little above it 😉
1 Comment

Posted by on December 11, 2010 in CentOS, Linux, php, Tips, Tricks, Web Services


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Open source – Port25

If you have trouble getting the PHP’s mail() function to work on your server.
If the function returned true, but never send the emails to target account.
Some ISP’s block port 25 (mail port), so you can’t send directly but you can send indirectly using your ISP’s mail server. 😉

Many email providers keep lists of IP addresses and block incoming mail, or move it immediately to a junk/spam folder.

There are some Open Source solutions to filter your mail problems..
You can check Open Source MTA here

Here list some MTAs as

  1. postfix
  2. qmail
  3. exim
  4. sendmail

Above MTA don’t handle integrated reporting, bounce management, and spam management, reporting.

PowerMTA: PowerMTA (this is not open source) provides the unique features and capabilities required by email service providers and enterprises to maximize the effectiveness of email marketing and customer communications, handle integrated reporting, bounce management, and spam management, reporting etc.


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