May 202014
 

Article based on the original work of  Travis Zajkowski first posted on his blog

As first thing, this is a good definition of subner, from wikipedia:

subnetwork, or subnet, is a logically visible subdivision of an IP network. The practice of dividing a network into two or more networks is called subnetting.

All computers that belong to a subnet are addressed with a common, identical, most-significant bit-group in their IP address. This results in the logical division of an IP address into two fields, a network or routing prefix and the rest field or host identifier. The rest field is an identifier for a specific host or network interface.

The routing prefix is expressed in CIDR notation. It is written as the first address of a network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 192.168.1.0/24 is the prefix of the Internet Protocol Version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. The IPv6 address specification 2001:db8::/32 is a large address block with 296 addresses, having a 32-bit routing prefix. In IPv4 the routing prefix is also specified in the form of the subnet mask, which is expressed in quad-dotted decimal representation like an address. For example, 255.255.255.0 is the network mask for the 192.168.1.0/24 prefix. Traffic between subnetworks is exchanged or routed with special gateways called routers which constitute the logical or physical boundaries between the subnets.

The benefits of subnetting vary with each deployment scenario. In the address allocation architecture of the Internet using Classless Inter-Domain Routing (CIDR) and in large organizations, it is necessary to allocate address space efficiently. It may also enhance routing efficiency, or have advantages in network management when subnetworks are administratively controlled by different entities in a larger organization. Subnets may be arranged logically in a hierarchical architecture, partitioning an organization’s network address space into a tree-like routing structure.

When you configure a server or a service it’s useful to know what’s the complete IP Address, so there are several different Subnet Calculators available for command line use on Linux. Two popular ones are:

ipcalc
sipcalc

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May 192014
 

Dstat is a versatile replacement for vmstat, iostat, netstat and ifstat. Dstat overcomes some of their limitations and adds some extra features, more counters and flexibility. Dstat is handy for monitoring systems during performance tuning tests, benchmarks or troubleshooting.

Dstat allows you to view all of your system resources in real-time, you can eg. compare disk utilization in combination with interrupts from your IDE controller, or compare the network bandwidth numbers directly with the disk throughput (in the same interval).

Dstat gives you detailed selective information in columns and clearly indicates in what magnitude and unit the output is displayed. Less confusion, less mistakes. And most importantly, it makes it very easy to write plugins to collect your own counters and extend in ways you never expected.

Dstat’s output by default is designed for being interpreted by humans in real-time, however you can export details to CSV output to a file to be imported later into Gnumeric or Excel to generate graphs.
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May 132014
 

For what I know there isn’t an official google drive application for Linux and so after looking around I’ve found that there are some interesting project that you can use to access your data on Google Drive from your linux, and in particular today I’d like to show 2 of them:

Grive and Grive Tools: These 2 tools are good if you want to use Google Drive on your laptot or Desktop or in general in a graphical environment.

google-drive-ocamlfuse: This is more suited if you want to mount your Google Drive from a server or from a terminal, in fact this software will mount your Google Drive as File System and you’ll be able to move inside it and see all your files, like a local file system.

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May 102014
 

terminal1.jpg
Your server appearing pretty slow could be many things from wrong configs, scripts and dodgy hardware – but sometimes it could be because someone is flooding your server with traffic known as DoS ( Denial of Service ) or DDoS ( Distributed Denial of Service ).

Denial-of-service attack (DoS attack) or Distributed Denial-of-service attack (DDoS attack) is an attempt to make a machine or network resource unavailable to its intended users. This attack generally target sites or services hosted on high-profile web servers such as banks, credit card payment gateways, and even root nameservers. DoS attacks are implemented by either forcing the targeted computer to reset, or consuming its resources so that it can no longer provide its services or obstructs the communication media between the users and the victim so that they can no longer communicate adequately.

In this small article you’ll see how to check if your server is under attack from the Linux Terminal with the netstat command

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May 022014
 

You could have come across the term, “cPanel” if you have been searching around for a shared Linux web hosting or logged into cPanel right now if have got a new hosting account. cPanel is a web-based tool that can help you manage the files on your website, email associated with your domain, and basically manage almost everything about your hosting. It is extremely user-friendly and can enable one to manage their hosting even if you they do not know much about web hosting.

There are several alternatives to cPanel like, Webmin, Virtualmin, and Zpanel, but cPanel simply blows its competitors out of the water, because of it user-friendly interface and features. When you sign up for a shared web hosting for your online business or personal websites, 99.9% of the time you will have cPanel to help you manage your hosting. Although, a lot of professionals like to use a console to get things done, which can give you major geek credits, for someone who is just starting out in the world of hosting, learning the basics about cPanel is probably the first step to accomplish tasks quicker.
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