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Spam Filtering with Sendmail Milters and Greylisting Publish Date: Jun. 10, 2004
With spam, viruses, worms, and trojan horses consuming an ever-increasing amount of mail traffic, mail filtering is more important than ever. So is mail server flexibility. Sendmail's milters allow administrators and programmers to control almost every step of the mail process. Emmanuel Dreyfus explains how to write a milter by demonstrating his anti-spam greylisting system.
Mail-Filtering Techniques Publish Date: May. 20, 2004
With spam, viruses, worms, and trojan horses consuming an ever-increasing amount of mail traffic, mail filtering is more important than ever. Emmanuel Dreyfus explains the basics of mail filtering and compares several different approaches.
IRIX Binary Compatibility, Part 6 Publish Date: Apr. 3, 2003
With IRIX threads emulated, it's time to emulate share groups, a building block of parallel processing. Emmanuel Dreyfus digs deep into his bag of reverse engineering tricks to demonstrate how headers, documentation, a debugger, and a lot of luck are helping NetBSD build a binary compatibility layer for IRIX.
chrooted ntpd in NetBSD Publish Date: Feb. 13, 2003
Recently, support was added to the NetBSD Operating System to run the
Network Time Protocol Daemon (ntpd) under an unprivileged user ID in a
chroot jail. In the second of two articles, Emmanuel Dreyfus explains the changes required to allow ntpd to do its magic while chrooted.
Securing Systems with chroot Publish Date: Jan. 30, 2003
Recently, support was added to the NetBSD Operating System to run the
Network Time Protocol Daemon (ntpd) under an unprivileged user ID in a
chroot jail. In the first of two articles, Emmanuel Dreyfus explains buffer overflows -- a typical Unix security flaw, then explains a chroot jail and the motivation for running a program in it.
Emmanuel Dreyfus Interview Publish Date: Jan. 9, 2003
A recent update of the NetBSD Mach and Darwin binary compatibility page left several people wondering if OS X apps now ran nearly-natively. Emmanuel Dreyfus, one of the leaders of the project, has graciously agreed to an interview. What's this binary compatibility and what does it mean?
IRIX Binary Compatibility, Part 5 Publish Date: Dec. 19, 2002
How do you emulate a thread model on an operating system that doesn't support native threads (in user space, anyway)? Emmanuel Dreyfus returns with the fifth article of his series on reverse engineering and kernel programming. This time, he explains thread models and demonstrates how NetBSD emulates IRIX threads.
IRIX Binary Compatibility, Part 4 Publish Date: Oct. 10, 2002
Emmanuel Dreyfus tackles the chore of emulating IRIX signal handling on NetBSD.
IRIX Binary Compatibility, Part 3 Publish Date: Sep. 19, 2002
Emmanuel Dreyfus shows us some of the IRIX oddities, the system calls that you will not see anywhere else.
IRIX Binary Compatibility, Part 2 Publish Date: Aug. 29, 2002
Emmanual Dreyfus shows us how he implemented the things necessary to start an IRIX binary. These things include the program's arguments, environment, and for dynamic binaries, the ELF auxiliary table, which is used by the dynamic linker to learn how to link the program.
IRIX Binary Compatibility, Part 1 Publish Date: Aug. 8, 2002
This article details the IRIX binary compatibility
implementation for the NetBSD operating system. It covers creating a new emulation subsystem inside the NetBSD kernel as well as some reverse engineering to understand and reproduce how IRIX internals work.
