Knowledge
Technical Languages
- - C (10y, on a daily basis)
- - HTML / CSS (10y), PHP (9y), SQL (9y)
- - TCL (10y), VB (9y)
- - Bash scripting (11y), batch files (14y)
- - Assembler (10y, limited use)
Languages
- - Dutch (native)
- - English (good)
- - German (reasonable)
Main Technical Skills
- - C programming
- - Networking
- - Security: securing, code auditing, penetration testing
- - System administration (Linux/Windows)
Familiar OS's and Software
- - Linux (11y): Debian, RedHat/Fedora
- - Samba, Apache, PHP, various ftpds, mysql, etc.
- - gcc, gdb, gcov, gprof, MS Visual C++
- - cvs, svn
- - IRCd, Eggdrop, Various irc services
- - Openwall, Grsecurity (w/RBAC), Tripwire, ..
- - Tcpdump, Ethereal, Ngrep, Snort, ..
- - Windows NT/95/98/2000/XP Client
- - Windows NT Server
Non-IT interests/hobby's
- - Science
- - Photographing
- - Hiking in mountains
- - In-depth news / documentaries
- - Books about "recent" history (20th century)
Work Experience
MLHJ - System-/Network administrator 2007-present
The Montessori Lyceum Herman Jordan is a high school (12-18y) for ~700 students, located in The Netherlands.
- - After 5 years, back at my old employer as a part-time sys-/netadmin
- - School now has ~200 computers
- - Work is still very much diverse, however, key aspects are: security (wifi, servers, etc.) and server management.
SafeWire - Software developer, Consulting, Server Management 2007-present
Started a new company (still in development) with a friend, specialized in VPN (Virtual Private Network)
solutions. Targetted at small and medium businesses located in The
Netherlands.
VULNSCAN - Software developer, Consulting, Server Management 2005-present
Started my own company because the success of writing paid software/consulting as a hobby was getting a bit out of hand ;)
- - Providing custom coding and consultancy to various companies troughout the world
(US, Germany, France, Belgium, Luxembourg, Norway, Hungary, Mexico, Australia, ..).
- - Coding/consultancy includes large projects for commercial companies,
such as coding and/or maintaining: customer support systems, messenging services, restricted/paid chat systems, ..
- - Also doing non-IRC related consultancy such as server managament (security hardening, apache, proftpd, mysqld, etc), PHP coding, and more
MLHJ - System-/Network administrator 2001-2002
The Montessori Lyceum Herman Jordan is a high school (12-18y) for ~700 students, located in The Netherlands.
- - Converted the entire network from coax to UTP
- - Installed a secure internet router/firewall & new Internet uplink
- - Merging internal networks, converting a network from Novell to Linux+NT
- - A _lot_ of Windows (NT/2000) and Linux security measures both at server and desktop (you know students..)
- - Installing backup systems, UPS, writing backup procedures
- - Basic hardware installation/management, ended up with 100 desktops for students throughout the school.
Volunteer Projects
UnrealIRCd - Head coder 2001-present
UnrealIRCd is a highly advanced IRCd (chat) server, it is the most popular one
on small- and medium-sized networks (<~3000 users).
- - Implemented spamfilter: to my knowledge the first real spam filter at the IRCd level
- - Redesigned channelmode +f: A build-in anti-flood system in the IRCd, making it respond in real-time, also avoiding the need of bots
- - Implemented extended channelmodes system: allowing another 32 more channelmodes, all in a clear framework, fully modulized
- - Implemented extended bans: not originally my idea, but the first major ircd using this concept
- - Countless bugfixes and other small features
Other Projects
Here's a list of some of the projects I did in my spare time:
- SUBCOM, 1999 - A project that (mis)uses the ISDN protocol to allow some
limited free data transfer (10bps), this was before I had a cable connection
and my phone bills were getting expensive ;). Implemented via a modified
Linux kernel that hacked into ISDN layer 2 to send extra framedata when
calling (such as "calling party subaddress"). Included it's own protocol
(including segmentation), own chatserver, etc. It was a nice way to chat for
free ;).
- HokIRCd, 2001 - I wrote my own IRCd in VB (how un-leet), over 10.000
lines of code, using it's entire own protocol, zip, ssl, and most of
important of all supporting a mesh link topology. This was just a
proof-of-concept thing written in my summer vacation, it was never meant for
public/mass use. I gained a lot of experience from it however ;).
- Spoofit, 2001 - An utility that can blindly spoof a connection
from any IP address to Windows 95/98/NT/2000. It tries to guess
the ISN (Initial Sequence Number) range and then performs the spoof. It was
especially designed for use on the Internet from a normal *DSL/cable
broadband connection. It takes just a few seconds to spoof for W9X/NT,
and 5-10m for 2000+. Originally meant for releasing to the public, but for
some unknown reason never done ;)
- Honeypot, 2002 - A project where I set up my own honeypot (to
catch hackers). I also wrote several Linux kernel modules such as one that
locks down the system if a certain file is hit (rm -rf protection), a logger,
and some others I want to keep private ;).
- Security, 1999-2005 - While my publications (well, bugtraq posts) on security are quite
limited, I've been quite active in this field. I wrote my first exploit when I was
16, it was a buffer overflow that emulated a struct with function pointers,
you can find it here
(but please ignore my bad english from back then ;p). In the meantime I
occasionally mailed bugtraq/vuln-dev. Another thing I wrote was a tool
to check for apache servers being vulnerable to the chunked encoding
exploit, at that time I also warned several companies that there server was
vulnerable. My most recent proof-of-concept
is from 2004 and tries to crash OpenSSL applications vulnerable to the OpenSSL ASN.1 bug.
I noticed that for some reason nobody published an exploit/PoC, not even
months after the release of the advisory, hence I decided to post it after
several people requested it. Over time I've also kept several exploits private (although
never abused), such as: snmpd bof, eggdrop fmt bug, IIS 4 DoS, tcpdump DoS, Unreal Tournament DoS,
rcrypt/cryptcat crypto weakness, and more. Most of these vulns have been fixed since then.