A new vulnerability has been found that potentially affects most versions of the Linux and Unix operating systems, in addition to Mac OS X. Known as the “Bash Bug” or “ShellShock,” the GNU Bash Remote Code Execution Vulnerability could allow an attacker to gain control over a targeted computer if exploited successfully. And because Bash is everywhere on Linux and Unix-like machines and interacts with all parts of the operating system, everyone anticipates that it will have lot of repercussions. How does Shellshock work? Shellshock exploits a flaw in how …
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Linux Basics
SSH is a network protocol that provides secure access to a computer. When we need to connect to a remote computer via SSH, that computer should have an SSH server running on it. There are different ways a client can authenticate itself to the server. A typical authentication mode will be to enter a password when logging into a remote system. Using the below-mentioned steps we can directly login to Linux server without password authentication step. First, we will need to download PuTTY and PuTTYgen. PuTTY: the Telnet and SSH …
It is very easy to block IP (country wise) with the help of CSF the default firewall from Cpanel.But it is not the case when we try with IPTables. In this blog I will try to demonstrate how to Block IP from a certain country with the help of IPtables.For example purpose I choose Afghanistan and China.
We can always set time to the commands showed in history command as it will be totally a security measure and can be used for troubleshooting/fingerprinting a security threat. History command sample output before setting this variable is as below: 466 df -h 467 df 468 exit 469 nfsstat 470 find / -iname *.ppt Inorder to display date and time of execution along with the commands, use inbuilt variable HISTTIMEFORMAT to set the values as shown below: #export HISTTIMEFORMAT=’%F %T ‘ where, %F for setting year/month/day %T for setting time …
The cPanel update failed with the following error : Fatal: Your RPM database appears unstable. It is not possible at the moment to install a simple RPM. The RPM database is corrupted which is causing the problem. Follow the below steps to fix this issue: 1. mkdir /root/old_rpm_dbs/ 2. mv /var/lib/rpm/__db* /root/old_rpm_dbs/ 3. rpm rebuilddb 4. Then run, #upcp –force If you require help, contact SupportPRO Server Admin
The Master Boot Record (MBR) is the first 512 bytes of a storage device. The MBR is not a partition, it is reserved for the operating system’s boot-loader and the storage device’s partition table. MBR Total Size 446 + 64 + 2 = 512 Where, 446 bytes Bootstrap. 64 bytes Partition table. 2 bytes Signature. To backup the MBR: dd if=/dev/sda of=/path/mbr-backup bs=512 count=1 To restore the MBR and partition table: dd if=/path/mbr-backup of=/dev/sda bs=512 count=1 Restoring the MBR with a mismatching partition table will make your data unreadable. To …
DVDROM (Digital Versatile Disk Read-only memory) and CDROM (Compact Disc Read-only memory) are optical storage devices to store your data for future uses or for backups. Many people use these disks to store movies, photos etc. By default many older Linux machines will not allow you to see the content of them. This is due that, they are not mounted by default in your box. We have to mount them properly so that we can access their content. There are many ways to do mounting CDROM/DVDROMs. One of the classic …
We the internet users are always in search for speed and faster access, so as a site owner must provide both these to survive in this field of business. The Apache servers are most commonly used for internet So various tweaks are available for such servers, I am introducing one such module that will help you to have high speed in loading your sites, mod_pagespeed. mod_pagespeed is a module used for increasing the page speed loading time of the site. It has several filters that automatically optimize files like HTML, …
Log files are very important and valuable tool available in Linux system security. Logrotate is a log file manager program which provides the administrator with an up-to-date record of events taking place on the system. It may also be used to backup log files. It regularly rotates log files by removing old one from the system and creating new log files as the log files grow too large. This rotation is based on the age of the file, file size and can also set cron utility. It can also be …
Runlevel is a preset operating state on a Unix-like operating system. A run-level is a software configuration of the system that allows only a selected group of processes to exist. A system can be booted into (i.e., started up into) any of several run-levels, each of which is represented by a single-digit integer. Each run-level designates a different system configuration and allows access to a different combination of processes (i.e., instances of executing programs).