System Administration

Cisco Network Emulation with GNS3 in a Docker container

GNS3 is a fantastic piece of software, it glues together different open source software and allows to emulate a network that includes Cisco routers (using real Cisco firmware), Cisco switches (using IOU, Cisco IOS on Unix), Cisco ASA and any other devices that can run on Qemu or Virtual Box emulator.

It also allows to connect the virtual network to the physical network, it is possible to access Internet in the emulated world and vice-versa. GNS3 is available on Windows, Mac OSX and on Linux, but it shines on Linux because, to use IOU, if you are not on Linux you need a Linux virtual machine running on VirtualBox.

But, because GNS3 glues together many moving parts, it can be troublesome to install everything and to have everything working seamlessly, for this reason i created a Docker image with everything installed, functioning and ready to be used on Linux (or in a Linux virtual machine running in Windows or Mac OSX).

Docker is another fantastic piece of software that, together with CoreOS and other cloud orchestration projects, like Google's Kubernetes, is one of the building blocks for the incoming Cloud Revolution.
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Microsoft Exchange: complex and dangerous by design

I am not a fan of Microsoft products, I don't like their complexity and the "dangerous by design" philosophy; recently I switched company and I am involved in implementing a data center for a public institution based primary on Microsoft Technology. One of this product is Microsoft Exchange; after many years of Unix System Management experience I didn't believe how flawed Exchange was until I red by myself the official Microsoft Exchange documentation (Microsoft Exchange Server 2003 Resource Kit).
Some items that really surprised me are the followings:
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Fighting Spam

The increase of Spam is a trend that started few years ago and it is continuously expanding, but to fight it there is plenty of good Open Source software. To use it effectively, anyway, it is needed a good knowledge of how spam floods our inboxes.

How spammers collect email addresses

The most used address gathering technique is using virus and spyware software that, without user awareness, gather email addresses from Outlook (or other email software) address-books and send this information to the spammers. Another popular address gathering technique is that of using web spiders to collect email addresses from web pages and newsgroups.
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