Jan Kratochvíl

Reverse-engineered undocumented parts of a Windows kernel file system API, particularly NT Cache Manager, and implemented a Windows file system compatibility layer for Linux. My implementation was tested with Windows NTFS (the project goal), FastFAT, CDFS (ISO 9660), and Ext2sd (Linux ext2). Only the NTFS file system was useful, as the other file system types were supported natively by Linux kernel. It provided a Linux kernel interface based on LUFS, GnomeVFS, and a custom command-line client.

The project delivered full security protection from possible malicious Windows drivers via chroot and setuid wrapping and the narrow communication channel using CORBA (ORBit2). The project also provided an XML-based file format for operations recording and replay for subsequent easy debugging of problem reports from users or customers. Its Windows kernel API emulation used original ntoskrnl.exe, ReactOS free software implementation, or my own implementation, specifically chosen for each supported Windows kernel API call. I wrote this in 2002-2003.

Developed network management software for automated provisioning of internet access to hotel and restaurant guests. The project provided the ability to print tickets for prepaid, time-limited internet access.

The project used VLANs to isolate hotel rooms and provide fully transparent connectivity and data access protection for hotel guests. It also featured ARP and DNS spoofing utilities to make the internet work, even on computers with statically configured IPv4 addresses, such as those from company networks at that time. I wrote this in 2004.

Developed my own multimedia messaging service (MMS) center to compete with cell phone operators. The project generated several earned-media articles in popular newspapers, but local cell phone operators soon blocked the service. The project provided better support than the MMS support of local cell phone operators at that time, in that my MMS center also provided the MMS message encapsulation part.

Developed IVR scripts based on the Asterisk Gateway Interface (AGI) to charge for MMSs on a phone number with high billing per minute. I used Asterisk and AGI on a 2x BRI PSTN voice card. The project also featured a Linux and Windows client to run on a user's computer as protection against firewalling by cell phone operators.

I wrote these in 2005.

Firmware for a laser shooting game gun along with software for communication with the guns for Amiga computers. I wrote the software in 1996, but I did not design or assemble the hardware for this project.

Coded as a preview of a possible future web database solution for a lawyers association. I wrote this in 1998 as my first dynamic web, with the back end in PHP 3.0. I also fixed one bug in PHP-3.0b6 and another in PostgreSQL 6.3.

Infrared remote control for home TV and multimedia appliances. It was written in 1997 and later superseded by LIRC, a more popular project. My project provided a local Linux client and a remote web interface.

An xBill game rewritten in 2000. The existing X11 codebase of the xBill game was ported to the GNOME UI, and the rewritten game allowed users to play the game over a network. It featured GNU Automake, Autoconf, and other frameworks that were popular at that time.

A bootable RAM file system for Amiga computers. I wrote this in 1995 when I had a floppy drive (no hard drive), which was very slow. The RAM-based file system made booting and all system operations much faster.

PortDiag can be used for low-level hardware diagnostics and control of hardware ports on Amiga computers. It supports all the bits of the four CIA ports, digital and analog parts of the game ports, and serial port TxD and RxD signals. I wrote this in 1996.

A mail filter for mail folders and spam dispatching. The rules are written in Perl for the users' convenience: store "=spam" if ($_=mimehead(body_first())->mime_attr("Content-Type")) && m#text/html#i.

Badblock-guess can recover all readable sectors of a damaged disk in minimal time. The functionality is similar to GNU ddrescue, but badblock-guess uses a smart algorithm to recover more data in less time with less additional damage to the disk media.

Provisioned my own GPRS data connection gateway for Nokia Communicator. This private gateway provided some security, as Nokia Communicator had only unencrypted telnet (instead of SSH). It also controlled battery charging cycles for the gateway modem. I wrote this in 1998.

Does your link suffer from a high packet loss (up to 70%)? Do you have a UNIX account on the public internet but no root privileges access there? This tool provides reliable, fast TCP (web proxy and SSH) connectivity while constantly retrying transmissions on a link of any quality.

A utility written in 1998 when CD burning software did not yet feature in-memory buffering and one could often lose expensive, recordable CD media as a result. This utility reads data as quickly as possible into its cache and, at the same time, writes the data as fast as possible to its output. It can also be used for buffering audio streams and other media.

KIX server can be used on Linux as a replacement for the proprietary KaliNix network game server (originally at http://kali.net). KIX is a free software replacement for existing Kali support in various games. I wrote this in 1998.

A developer tool for PC bootloader analysis that reports all sectors being read to display, its own boot floppy disk, or a serial port. It was a troubleshooting tool that was part of a larger team project, Partition Surprise. I wrote it in 2001.