Category Archives: Shell script

Observing packets on the wire flying by

Anyone who has ever tried to install a modem or configure an Internet connection has almost certainly wondered if there’s any traffic flowing back and forth from networks. Observing network traffic that is generated by a PC or Mac is … Continue reading

Posted in Computer network, IT Security, Linux, Shell script | Tagged , , , , , , , | Comments Off on Observing packets on the wire flying by

Using Elliptic Curve with an OpenSSL PKI

OpenSSL is a tool that can be used to setup a (simple) PKI, but in its most basic form a command line tool with an endless amount of options. I find myself searching for the correct syntax of OpenSSL to … Continue reading

Posted in Crypto, IT Security, Shell script | Tagged , , , , , , , , , , , , , , | Comments Off on Using Elliptic Curve with an OpenSSL PKI

Email and malware dissection, Part II

If you’re running a mail server on the Internet, you will surely be familiar with spam and malicious email. This post is the last part on how to identify and isolate malware in email while respecting your users’ email privacy. … Continue reading

Posted in email, IT Security, malware, Perl, Shell script | Tagged , , , , , | Comments Off on Email and malware dissection, Part II

Email and malware dissection, Part I

Phishing, Trojans, Worms and other malicious activity in email. These series of posts make quite a lengthy write-up on how to use Unix shell script and Perl to dissect large amounts of email all at once without disrespecting email privacy … Continue reading

Posted in email, FreeBSD, IT Security, Linux, Mac OS X, malware, Perl, Shell script | Tagged , , , , | Comments Off on Email and malware dissection, Part I

Tinkering with file encryption

Storing files overseas or “in the cloud” has become somewhat of an issue lately with spying activities of various nations. I think we’ve just seen the top of the iceberg, but at the same time I hope I’m wrong. In … Continue reading

Posted in Crypto, FreeBSD, IT Security, Mac OS X, Shell script | Tagged , , , , | Comments Off on Tinkering with file encryption

Resizing multiple images

I’m sure there are easier ways, and better I assume, to reduce the size of multiple images at once. But there was some point in time where I couldn’t resist the urge of solving this myself using ImageMagick and Tcl/Tk. … Continue reading

Posted in Image processing, Shell script | Tagged , , , , , , , | Comments Off on Resizing multiple images