Boot Process of a Linux Machine BOOTING PROCESS BIOS BootSector KernelInitilisation Init SysVinit scripts. BIOS(Basic Input Output System) Bios is a piece of software that is built-in to the machine,usually by being stored in the flash ROM on the motherboard. There are two purpose of BIOS,one it takes the machine from a power-on state ..
2.6.x kernel RPM BUG There is a possible bug in the 2.6.x kernels with rpm command, it may give you errors like this rpm -q glibc rpmdb: unable to join the environment error: db4 error(11) from dbenv->open: Resource temporarily unavailable error: cannot open Packages index using db3 - Resource temporarily unavailable (11) ..
Hacking Attacks - Prevention Some of the main steps are discussed here to harden your server. 1. Harden your systems (also called "lock-down" or "security tightening") by » Configuring necessary software for better security » Deactivating unnecessary software - disable any daemons that aren't needed ..
Error QM MODULES Function not implemented You would have come across the error " QM_MODULES: Function not implemented " while running the command lsmod or while restarting the apf. Have you ever thought of why you get this error 'QM_MODULES: Function not implemented'. The error is because of the latest upgradation ..
A new phpBB Worm There have been reports of WebWorm exploting PHPBB's urldecode vulnerability. The worm uses this to create a perl script on the server and start it. After the perl script starts it wipes itself out, then begans to search via google.com/advanced_search for exploitable viewtopic.php files part from the ..
Prevent server from SYN flood attack using tcp syncookies TCP syncookies functionality prevents attackers from blocking up your server by filling up the list of connections by using a clever algorithm and a little cryptography in the TCP sequence numbers. If you're using a fairly new version of Red Hat, you'll ..
Kernel Kernel Recompilation Steps 1. Download the latest kenel from www.kernel.org to /usr/src 2. Unpack the tar ball # tar -zxvf linux-x.x.x.tar.gz # cd linux-x.x 3. backup the .config file from /boot 4. Run the command make mrproper to remove the config file # make mrproper this removes the current .config and other files 5. Now lets start for kernel ..
BOOTING PROCESS: BIOS BootSector KernelInitilisation Init SysVinit scripts. BIOS(Basic Input Output System) Bios is a piece of software that is built-in to the machine,usually by being stored in the flash ROM on the motherboard. There are two purpose of BIOS,one it takes the machine from a power-on state to the point where it ..
Runlevels in Linux Linux operates in runlevel 3 - full multi-user mode. The following runlevels are defined in Red Hat Linux: 0 - Halt 1 - Single-user mode 2 - Not used (user-definable) ..
How to change default gateway Server needs to have a single default gateway. DHCP servers will automatically assign a default gateway to DHCP configured NICs, but NICs with configured static IP addresses will need to have a manually configured default gateway. This can be done with a simple command. This example ..
Linux or UNIX Recover deleted files - undelete files If you run rm command accidentally and deleted important a file, recovery becomes critical under Linux and/or UNIX oses. Since Linux is multiuser and multitasking operating system other users/process can overwrite deleted file disk space. So you need to take down system to ..
Boot Sequence In Linux Boot Process 1) BIOS 2) Master Boot Record (MBR) 3) LILO or GRUB 4) Kernel 5) init 6) Run Levels 1) BIOS Load boot sector from one of: Floppy CDROM Hard drive The boot order can be changed from within the BIOS. BIOS setup can be entered by pressing a key during boot up. The exact key depends varies, ..
What is GUI Computer systems that support two or more simultaneous users. All mainframes and minicomputers are multi-user systems, but most personal computers and workstations are not. Another term for multi-user is time sharing. ..
What is shell in linux A shell is a program that provides the traditional, text-only user interface for Unix-like operating systems. Its primary function is to read commands that are typed into a console (i.e., an all-text display mode) or terminal window (an all-text window) in a GUI (graphical user interface) ..
What is lilo Lilo means last in last out . LILO is a versatile boot loader for Linux. It does not depend on a specific file system, can boot Linux kernel images from floppy disks and hard disks, and can even boot other operating systems. One of up to sixteen differernt ..