Install nfdump and nfsen netflow tools in Linux

Using nfsen it is possible to view IP traffic statistics on Linux interfaces including the graphs showing data sent and received (see the screenshot to the right) as well as historical information about all data transfers. So after you’ve configured nfsen and nfdump to monitor traffic on certain Linux server or router you’ll be able to answer the following example questions: What IP was downloading data through 48161 last Wednesday? […]

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Quick Tip: Increase port range available for applications

By default an average Linux distribution allows applications to use the following TCP port range for outgoing connections: 32,786-65,536. That’s why your system can handle up to 28,232 TCP sessions at time. Notice, this is more than enough if your Linux system is installed on the laptop or desktop and you just use it for occasional visits to facebook.com, gmail.com and linuxscrew.com (yeah!). But if you run proxy/webcache like squid […]

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Namebench: cross-platform DNS benchmarking tool

It was long time ago when I wrote here last time but today I’d like to share the link to an application that would be appreciated by everyone starting from Linux starter wishing to speed up his/her Internet connection and ending with system administrators who may want to run benchmarks and run stress tests against certain DNS service(s). I am talking about Namebench. This is cross platform tool written in […]

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How to monitor traffic at Cisco router using Linux (Netflow)

By default Cisco IOS doesn’t provide any traffic monitoring tools like iftop or iptraff available in Linux. While there are lots of proprietary solutions for this purpose including Cisco Netflow Collection, you are free to choose nfdump and nfsen open source software to monitor traffic of one or many Cisco routers and get detailed monitoring data through your Linux command line or as graphs at absolutely no cost. Below is […]

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The easiest way to split and merge pdf files in Ubuntu

The easiest way to split, merge or edit pdf files in Ubuntu is to use pdftk utility. This rather old (latest version was released in 2006) but still simple and powerful program can be installed in Ubuntu (Debian or any deb-family Linux distribution) by the following command in terminal: sudo aptitude install pdftk (if you run Fedora, RedHat or CentOS use this one: sudo yum install pdftk) Split large pdf […]

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