You can easily block SSH server attacks including dictionary based attacks and brute force attacks using a Python based script - DenyHosts. It analyzes the sshd log messages to determine what hosts or IPs are attempting to hack into your system. STEP 1: Enable Rpmforge Repo in your system, For 32bit CentOS / RHEL Linux enter: # rpm -Uhv...

“MemCached” is a high-performance, distributed memory object caching system, generic in nature, but intended for use in speeding up dynamic web applications by alleviating database load.  Activate the RPMForge repository, #wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el5.rf.i386.rpm # rpm -ivh rpmforge-release-0.5.2-2.el5.rf.i386.rpm Now install memcache rpm from rpm...

Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. As of October 2010, Firefox is the second most widely used browser, with 30% of worldwide usage share of web browsers. In Germany, Firefox is the most popular browser with 60% usage says Wikipedia. To install Firefox 4 on Fedora Linux, # vim ...

In Linux you can use faillog command to display failed login attempts or you can set login failure limits. faillog formats the contents of the failure log from /var/log/faillog database / secure log file. It also can be used for maintains failure counters and limits. For RHEL/CentOS Linux 5.x, you need to modify /etc/pam.d/system-auth file to monitor or track failed login attempts. You need to...

Istanbul is a desktop session recorder for the Free Desktop. It records your session into an Ogg Theora video file. To start the recording, you click on its icon in the notification area. To stop you click its icon again. It works on GNOME, KDE, XFCE and others. It named Istanbul because, Istanbul as a tribute to Liverpool's 5th European Cup triumph in Istanbul on May 25th 2005. To install Istanbul, # yum...

Backing up MySQL database is a very important system administration task, and should generally be run automatically from cron. We will use the mysqldump utility included with mysql to dump the contents of the database to a text file that can be easily restore. # mysqldump -h localhost -u root -p root_password DataBase > DB_name_Bkp.sql This will generate a text file containing ...

“ViCompress HTTP proxy server reduces download time by gzip compressing text pages before sending them on the client. This results in faster download times, especially over slow network connections. ViCompress works with existing web servers and web browsers. All modern browsers (Internet Explorer, Firefox, Safari, Chrome) recognize gzip-encoded data, and will automatically decompress the data on the f...

For mysql, the system administrator user is called root. We will use the mysqladmin utility from a command line to set the new password. Default password is not secured at all. By default in RedHat, Fedora and Centos default password is null. So it is always better to set root password. To re-set root password, first stop mysql service. # service mysqld stop # mysqld_safe...

The mysqldump client is a backup program originally written by Igor Romanenko. It can be used to dump a database or a collection of databases for backup or transfer to another SQL server (not necessarily a MySQL server). The dump typically contains SQL statements to create the table, populate it, or both. However, mysqldump can also be used to generate files in CSV, other delimited text, or XML...

If you run a dual-boot system with Linux and Windows, and reinstalling Windows XP after OS corrupt.  Windows XP will wipes over write grub entry or writing MBR sector. To recover GRUB, STEP 1: Boot off the Live CD enter into rescue mode, STEP 2: Open a Terminal and type in the following commands, noting that the first command will put you into the grub “prompt”, and ...

If you are using Linux Desktop Operating System and do not want to set up an email server, use GMail account to relay emails. On Desktop OS, we can use GUI Email Clients, which supports POP3/IMAP to send an email but how about /usr/bin/mail or from cmd prompt? To fulfil your requirement, you need to install a simple program called ssmtp. It accepts a mail stream on standard input...

After downloading ISO file from Fedora/CentOS, you can check the integrity of the ISO-file with a checksum, the md5sum. The mirror will offer you a separate text file to download with a 128 bit string of characters. This string has to be exactly the same as the one you get when you do: # md5sum file.iso 0c0f8ff9b6fb60a4778288de0d9e7f46  file.iso We assume that, you have downloaded ...

Fileop utility does file operation on the filesystem and gives the ops/sec for each operation. This tool will be useful to test your filesystem performance as well as storage performance. Or, if you are going to select a filesystem or storage that is going to host huge number of small files (like source codes), then fileop can be used for benchmarking. First Install  ...

Rsync is a fast and extraordinarily versatile file copying tool. It can copy locally, to/from another host over any remote shell, or to/from a remote rsync daemon. It offers a large number of options that control every aspect of its behaviour and permit very flexible specification of the set of files to be copied. It is famous for its delta-transfer algorithm, which reduces the amount of data...

When you install a dual-boot of Linux, one of the frustrating things that you’ll immediately notice is that Linux is set as the default operating system in the Grub loader. If you want to change default Operation System instead of Linux, there’s an easy way to switch back to using Windows as the default. Open /boot/grub/menu.lst, # vim /bo...

bzip2 compresses  files  using  the Burrows-Wheeler block sorting text compression algorithm, and Huffman coding.   Compression  is  generally considerably   better   than   that   achieved   by  more  conventional LZ77/LZ78-based compressors, and approaches the performance of the  PPM family of statistical compressors. To list the contents of a tar.bz2 file, use tar command as follows: ...

Do you lost or forgot mysql root password ? No problem...! You can recover MySQL database server password with following steps. First Stop mysql service. # /etc/init.d/mysqld stop Start MySQL server without password: # mysqld_safe   - -skip-grant-tables & Connect to mysql server using mysql client: # mysql -u root Setup new MySQL root user password mysql> use mysql; mysql> update user set p...

There are various methods to run multiple instances of mysql (on different ports) on the same machine. Here I have used the same binary and used a separate configuration file (with separate port, pid, socket and data directory). We need to create new directories for our datadir and log folder (if used). Also we need to assign proper permissions on those folders: # mkdir /var/lib/mysql2 # chown -R mysql.mysql...

memtester is a user-space utility for testing the memory subsystem in a computer to determine if it is faulty. It does a good job of finding intermittent faults and non-deterministic faults. It has many tests to help catch borderline memory. memtester should compile and run on any 32- or 64-bit Unix or Unix-like system. Download latest version of memtester from...

Nginx quickly delivers static content with efficient use of system resources. It can deploy dynamic HTTP content on a network using FastCGI handlers for scripts, and can serve as a very capable software load balancer. Nginx uses an asynchronous event-driven approach to handling requests which provides more predictable performance under load, in contrast to the Apache HTTP server model that uses a threaded or...

Wireshark Network Analyzer is use full to track network packets. To sniff MySQL packets and decoding it, we will use mysqlsniffer. Note: This will not usually work for local connections. First, install libpcap-dev, which is the development library that allows an application to sniff network packets. $ sudo  apt-get install ...

The iostat command, Report Central Processing Unit (CPU) statistics and input/output statistics for devices, partitions and network file systems (NFS). The iostat command generates reports that can be used to change system configuration to better balance the input/output load between physical disks. The -n option displays the NFS disk statistics. Data displayed are valid only with kernels...

As you login as “root” right from booting the system, all the privileges are set to root, what makes your system more vulnerable to your own mistakes and those wishing to enter your system. As you login as normal user, the privileges are limited, thus it´s safer. To be able to do administrative tasks you can temporally login as root using “su” in a console/terminal, that way the root privileges ...

Dropbox is a Web-based file hosting service operated by Dropbox, Inc. which uses cloud computing to enable users to store and share files and folders with others across the Internet using file synchronization. It was founded in 2007 by MIT graduates Drew Houston and Arash Ferdowsi as a Y Combinator startup says Wikipedia.   To install DropBox on your system, download appropriate rpm for your...

MySQL is a simple SQL shell (with GNU read line capabilities). It supports interactive and non interactive use. When used interactively, query results are presented in an ASCII-table format. When used non interactively (for example, as a filter), the result is presented in tab-separated format. The output format can be changed using command options. After Installation of MySQL on Linux System, start it by, #...