Phone call as Nagios notification

Some time ago I found it pretty useful to configure Nagios monitoring system to send me a phone call in case of some critical problem. If some mission critical application goes down at night most probably you’ll miss an e-mail or sms notifying about that but won’t miss a telephone call to your cell phone. Honestly a telephone call is much more notorious rather than IM message notification or, again, […]

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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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Sendmail for virtual users with procmail, spamassassin and dovecot

Today I’d like to describe setup of sendmail that allows to establish receiving of e-mails for certain domain and sort incoming messages between virtual users. Those users must be able to fetch received e-mails via POP3 or IMAP protocols with or without TLS encryption. The key aspect of this kind of setup is that we will make sendmail working with virtual users which aren’t present in /etc/passwd so once it’s […]

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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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