Alok Pandey zealfire

Linux is being used in more and more tight places—devices or situations where multiple gigabytes of storage or dozens of megabytes of RAM are simply not available. Many Linux Journal articles have addressed this growing embedded systems space. Here, I will describe a terrific open-source tool for people needing a suite of utilities for use in these tight places.

BusyBox is a single-binary application that includes the capabilities of more than 70 standard Linux utilities. The BusyBox project was started by Bruce Perens when he was leading the Debian project. Many others have contributed code since then; the project is currently maintained by Erik Andersen, who also maintains a web page for it at http://busybox.lineo.com/. (BusyBox is sponsored by embedded Linux vendor Lineo, Inc. See http://www.lineo.com/.)

The corresponding standard utilities that BusyBox replaces occupy about 1.5MB of disk space in a standard Linux system. The BusyBox program uses only 260KB of disk space; it can even be compiled to inclu

Common table Expression :- Common table expression can be defined as a temporary result set or in other words its a substitute of views in SQL Server. Common table expression is only valid in the batch of statement where it was defined and cannot be used in other sessions.

Syntax of declaring CTE(Common table expression) :-

with [Name of CTE] as ( Body of common table expression )

netstat and lsof both crawl /proc//fd to associate processes to ports/sockets, and /proc//fd doesn't get populated for kernel threads AFAIK.

lockd is always a kernel thread - at least on modern (newer than say 2.2) kernels.

The DHCP lease renewal process is the process by which the DHCP client renews or updates its IP address configuration data with the DHCP server.

The DHCP client renews its IP configuration data prior to the expiration of the lease time. If the lease period expires and the DHCP client has not yet renewed its IP configuration data, then the DHCP client loses the IP configuration data and begins the DHCP lease generation process again.

The lease renewal process is the result of the lease period value. The lease period value ensures that DHCP maintains the IP address information and that clients regularly update or renew their IP address configuration data. Having DHCP maintain this information means that you can manage IP addressing from the DHCP server.

The client must renew its IP configuration data before the lease period expires. At specific intervals, a DHCP client attempts to renew its lease to ensure that it has up-to-date configuration information.

At any time during the lease period, the DHCP client

CR and LF are control characters, respectively coded 0x0D (13 decimal) and 0x0A (10 decimal).

They are used to mark a line break in a text file. As you indicated, Windows uses two characters the CR LF sequence; Unix only uses LF and the old MacOS ( pre-OSX MacIntosh) used CR.

An apocryphal historical perspective:

As indicated by Peter, CR = Carriage Return and LF = Line Feed, two expressions have their roots in the old typewriters / TTY. LF moved the paper up (but kept the horizontal position identical) and CR brought back the "carriage" so that the next character typed would be at the leftmost position on the paper (but on the same line). CR+LF was doing both, i.e. preparing to type a new line. As time went by the physical semantics of the codes were not applicable, and as memory and floppy disk space were at a premium, some OS designers decided to only use one of the characters, they just didn't communicate very well with one another ;-)

Most modern text editors and text-oriented applications offer opti

How does HTTPS work? HTTPS is based on public/private-key cryptography. This basically means that there is a key pair: The public key is used for encryption and the secret private key is required for decryption.

A certificate is basically a public key with a label identifying the owner.

So when your browser connects to an HTTPS server, the server will answer with its certificate. The browser checks if the certificate is valid:

the owner information need to match the server name that the user requested. the certificate needs to be signed by a trusted certification authority. If one of these conditions is not met, the user is informed about the problem.

	Logical volume mangaer is widely used technique for deploying logical rather than physical storage. With LVM "logical" partitons can span across physical harddrive and can be resized.

	So, in days when techonology was not so advanced, need to store data was less and hence we had physical drives of smaller size but with advance in technology the need to store data grew and hence the size of the physical drive so they were stacked one over the other to incress the size of storage. The problem with this was if i had a physical volume 0f 40gb stacked over another 40gb i will be not be able to store continuos data which extend upto 60gb and for that we need a hardrive of 80gb. This was costly job.

	So they come up "LVM" which allows mutiple harddrive to combine into one,fooling OS that we are actually using single hard drive instead of mutilple so the OS can span a data across a multiple hard drive thinking as one and this reduce the need of purcahsing new hard drive.


	So these physical drive are called "Physic

	DHCP Failover is a mechanism whereby two DHCP servers are both configured to manage the same pool of addresses so that they can share the load of assigning leases for that pool, and provide back-up for each other in case of network outages.

	Failover partnerships are configured per pool, so one DHCP server may have several active partnerships with different peers. The configuration elements of DHCP Failover are to establish peering relationship first (via the failover peer declarations in dhcpd.conf), and then to establish which pools will use the partnership by adding the failover peer option to the pool declarations individually.

	For more information and a sample configuration, please refer to: A Basic Guide to Configuring DHCP Failover

	dhcpd will only accept inbound TCP connections from its configured failover peers
	But note that the dialogue between failover partners is neither encrypted nor authenticated. Since most DHCP servers exist within an organization's own secure Intranet, this would be an unn

	t depends on the vpn configuration. To check how it is in your case check your default gateway:

	Windows (in command prompt):

	route print
	Linux (in console)

	netstat -nr
	Look for network destination 0.0.0.0 (win) or default (linux). If it set to your local subnet gateway - not entire traffic is going through vpn. Any other case - all traffic through vpn.

	Integrated Lights-Out (iLO) is a remote server management processor embedded on the system boards of HP ProLiant and Blade servers that allows controlling and monitoring of HP servers from a remote location. HP iLO management is a powerful tool that provides multiple ways to configure, update, monitor, and run servers remotely.

	The embedded iLO management card has its own network connection and IP address to which server administrators can connect via Domain Name System (DNS)/Dynamic Host Configuration Protocol (DHCP) or through a separate dedicated management network. iLO provides a remote Web-based console, which can be used to administer the server remotely. The iLO port is an Ethernet port, which can be enabled through the ROM-Based Setup Utility (RBSU).