Presented at
REcon 2010,
July 10, 2010, 4:20 p.m.
(60 minutes)
SDSL is a trailing-edge telecom technology that was originally intended to fill the gap between consumer ADSL and business T1/FT1 services. When I started working with SDSL in 2004, I had chosen it because it allowed me to remain a "business" customer (as opposed to consumer/ residential), have symmetric up & down speeds (I would rather have a low symmetric speed than high asymmetric), go faster than ISDN, yet pay only $150 to $180 per month instead of upwards of $500 for a T1. Over the past 5 years I have successfully carried out a project which allows low-speed SDSL (from 160 kbps to T1 speeds) to be used as a still-available replacement for ARPANET and for the old 1980s-style Internet, for those who miss the latter. More specifically, I have developed a way to use SDSL with traditional 1980s routers of the late ARPANET / early Internet era. ARPANET and early Internet ran over 56 kbps DDS and other leased lines; a line of that type is a pipe that carries a synchronous serial bit stream. The WAN interfaces on the classic 1980s / early 1990s routers are thus designed to attach to synchronous serial bit stream media. As it happens, SDSL is also a synchronous serial bit stream, but because it came about in the days when traditional WAN interfaces were going out of fashion in favor of Ethernet, CPE that would allow SDSL to be used in the old-fashioned manner was never made widely available. When I started working with SDSL in 2004, it was severely hobbled by the fact that the only type of CPE available for it were Ethernet-presenting DSL "modems" and routers much like those for consumer ADSL. Not being able to obtain a non-Ethernet CSU/DSU type of CPE device for SDSL, I had set out to design and build one myself, and 5 years later I have scored a complete & total success. The challenge was further complicated by the fact that SDSL/2B1Q was never a real standard, only somewhat of a pseudostandard with a variety of incompatible proprietary flavors. In this talk I will share the highlights of my journey which has brought me to the present state of having a CSU/DSU-like device which attaches SDSL to a 1980s/90s router's non-Ethernet WAN interface. This journey included social engineering ventures with several legacy SDSL infrastructure vendors, brute force cracking of an encrypted ZIP with SDSL transceiver chip control software source code, and lots of hardware, firmware and wire protocol reverse engineering. Related project website: http://ifctfvax.Harhan.ORG/OpenWAN/
Presenters:
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Michael Sokolov
I was born and raised in what was then USSR. I grew up with a computer architecture that was a Soviet clone of DEC's PDP-11; Russian and PDP-11 assembly were my equally native first languages. After being dragged kicking and screaming into the (much inferior to DEC) IBM PC-compatible architecture around age 11, I had been a DOS jockey for a while. In my DOS days I had studied everything there was to know about floppy disk copy-protection schemes (and the underlying physics of magnetic recording and the workings and idiosyncrasies of the standard controllers) in the process of developing Floppy Disk Analyser, a copy-protected floppy disk copying tool. I had also delved heavily into the world of 386 memory managers and the use of protected mode in the DOS environment (DOS extenders etc), and wrote my own MMM386 memory manager in the process.
Upon reaching the independent adult status I had joyfully said "good riddance" to the PeeCee (pee sea) architecture and returned to my DEC roots. I have fully embraced DEC's VAX architecture (PDP-11's direct successor), but just the hardware part of it. Instead of DEC's OSes like VMS, I run UNIX - and not any UNIX, but UC Berkeley's original UNIX for the VAX. As the world's last known site still running a VAX 4.3BSD variant in full production operation and planning to continue doing so indefinitely, I have become this operating system's de facto owner. My personal interests outside of hacking are very diverse and range from cell & molecular biology to exopolitics.
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