Monthly Archives: February 2013

Iproute2 Basics – Linux Tools for TCP / IP Networking, Traffic and Control

Iproute2 (or Iproute) consists of a variety of utilities for controlling TCP / IP networking and traffic control in Linux. It is actively maintained and frequently updated, and now considered the preferred package for modern network technologies which includes important network tools such as ip and tc, used for IPv4 and IPv6 configuration and traffic control. It currently replaces the outdated Net-Tools package encompassing commands such as ifconfig, route, arp, etc, which are now known to be mostly inadequate as they provide limited features.

To give you an idea just how obsolete the Net-Tools package is, it should be noted the last verified update was back in April, 2001. A common view among many developers and users is that these former Net-Tools utilities should be deprecated, however, most Linux distros still include them as old habits are hard to break. It is suggested, now is the time to familiarize yourself with some of the most common commands of the newer, feature packed Iproute2 utilities package to be more current with the times.
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Identify processes using files or sockets through Linux fuser command

For a Linux user, fuser is an efficacious utility. It stands for file user and as it suggests, it tells us the processes which are using the file. In this article we will study when and how to use Linux fuser command through practical scenarios and examples. Since in Linux everything is a file, we shall see later in the article, how it is used for directories and sockets too.
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A practical approach to learn Linux hexdump command

Hexdump is a Linux command that provides many options to dump file contents. It can dump file contents into formats such as hexadecimal, octal, ASCII, decimal. This command takes input either from a file or standard input. Hexdump is very helpful utility for debugging and verifying file contents written by any application program. In this article, we will first understand the basic usage of hexdump and then we will discuss some practical scenarios where hexdump command comes in really handy.
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Utilizing Iptables with Linux for Network Packet Mangling

Well known is the use of Iptables (read here) with Linux as a secure and effective firewall for your network connections, to customize and regulate all incoming, forwarded, and outgoing network traffic, and as a router or gateway for an internal LAN (Local Area Network). In addition to these and many more functions, Iptables can also be used to mangle, modify or alter parameters within the IP Header of a given Network Packet when necessary. The packets can be mangled in the built-in chains of PREROUTING (altering incoming packets prior to routing), INPUT (for packets coming into the box itself), FORWARD (for altering packets being routed through the box), and OUTPUT (for altering locally-generated packets before routing) and POSTROUTING (for altering packets as they are about to go out).
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