Blog
Articles, tutorials, and field notes on identity, integration, API management, and application security — spanning nearly two decades of hands-on work.
Capturing Network Communication Between Two Processes On the Same Machine…
Have you ever run snoop on Solaris or tcpdump on Linux or AIX and discovered that these tools cannot capture IP-based communication that occurs between two processes on the same machine? Or, Wireshark (formerly, Ethereal) on Windows? Only to discover the same limitation?
Capturing JVM TCP Traffic
Any time you have a distributed application, there is network communication involved. Capturing this network traffic can be instrumental in diagnosing and solving problems. Generally, to capturing network traffic, superuser privledges, timing, and a bit of luck is needed. Often, the appropriate…
Websphere v6.x Classloaders
Building on the ideas introduced in the last article, a J2EE Application servers classloaders are explored in this installment. In particular, Websphere Application Server v.6.x Classloaders are introduced. The J2EE Spec provides some guidance regarding J2EE Application Servers, but as with so many…
JEE 6 Draft Proposal Is Available For Public Review
Check out JSR 316 and this article. There is also a Slashdot.org thread on the subject.
Java Virtual Machine Classloaders
Classloaders are responsible for finding and loading classes that are requested in Java code executed inside a Java Virtual Machine. Classloader-related issues are among the most difficult to troubleshoot in the Java/J2EE technology stack.
Site Maintenance — Clean Up
The older articles predating the use of WordPress are slowly being copied over to the WordPress format. This provides a common look & feel and allows WordPress seach functionality, RSS feeds, and other goodies to work properly with the older content.
Computer Measurement Prefixes and Number Naming Conventions
I always forget the quantity prefixes above “tera”. Even more interestingly, one rarely thinks about the numbers’ names. For example, consider the number
JVM process Virtual Memory Usage (Resident Set Size) On A Linux 2.6.25 Kernel
This article expands on the previous Virtual Memory post by exploring Resident Set Size growth while running a Java program that will consume all available Java Heap memory. Four different JVM implementations are used to compare results of these experiments. These JVMs come from two different…
Google Browser Security Handbook
Google has released a Browser Security Handbook online. It can be found here.
Virtual Memory — Linux
It has been a couple of weeks since the last article was published. Recently, I had to dig into Virtual Memory on AIX to work through some issues. I realized there were several details I needed to explore further to understand Virtual Memory implementations. In particular, the implementation…
Dumping the contents of a JAAS Subject
In the last article, JAAS was introduced. An authenticated calling-entity (perhaps a user), has a JAAS Subject. This JAAS Subject contains some combination of Principals, Public Credentials, and Private Credentials. It can be very helpful to dump the contents of this JAAS Subject for debugging…
JAAS Authentication — An Introduction
This article introduces JAAS authentication via a relatively simple example. The example presented here is based upon the Sun tutorial of the same subject. The thinkmiddleware.com example extends the tutorial to use LDAP to authenticate users.