With much of the web switching to HTTPS and at least some people becoming more concerned about privacy, DNS has recently come into the spotlight because it provides an ISP with the ability to monitor which websites a user visits. Multiple mitigations have been proposed - Android for example is going …

The sed(1) stream editor is one of the most powerful tools from the classic Unix tool box. It is a close cousin to the ed(1) command line editor and a descendant of the ex(1) editor, the command line mode of vi(1). In this article I'll show …

In many applications it's important to react to failed logins and other security-critical events, for example to log the failed login attempt to a file or to display a captcha after repeated failures. Spring-based applications come with a simple mechanism to access this kind of information using Application Events.

Spring's …

In the old days, many Java APIs were fairly low level and pretty generic. You often had to explicitly select a concrete implementation, provide lots of parameters, and generally needed to know how things worked. This has changed in recent years - modern APIs provide lots of convenience functionality that raises …

The other day, I was trying to build a simple batch upload interface for a Java web application running Spring Boot with Spring MVC on Apache Tomcat. But when I tried reading the InputStream in my controller, it was always empty. Fortunately, this turned out to be quite easy to …

On Linux/Unix systems, there's occasionally the need to check whether a process is running. Some people use it for simple status checks or when building their own lifecycle scripts for startup and shutdown. I don't think it's a particularly good practice these days because all of this can be …

In my article on unattended upgrades I described how to set up an Ubuntu system to install security upgrades automatically. This is convenient for small setups, but in an enterprise environment you typically want to perform some QA before applying the change. A better solution is to have your monitoring …

Thanks to Ubuntu 16.04 which includes a fairly recent Nginx version, I have now enabled HTTP/2 on my private server. Of course, I also wanted to verify whether my configuration change had any effect - after all, there is no visible change (except for a little speed-up). One option …

There's more to migrating a complex site to HTTPS than just enabling TLS in your web server or reverse proxy. All links to embedded resources like style sheets, images, or scripts need to be served via HTTPS and potentially have to be rewritten. In a well-designed site that's not an …

A couple of days ago, Wordpress.com announced that they are now supporting TLS for custom domains (which is how this blog is hosted). There are many reasons for not hosting a blog yourself even if you have the necessary skills, like not having to deal with security updates and …