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 assign range of IP addresses in Linux?

As we know Linux allows to assign almost unlimited number of IP addresses to its interfaces. Such additional IPs applied to the same NIC are known as secondary IP addresses or just secondaries. Some time ago i faced a problem on how to apply about 500 IP addresses to one Linux box and then ensure that all of them get online after Linux reboots. There are several ways to accomplish […]

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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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