Bookmarks for July 13th through July 30th

These are my links for July 13th through July 30th:

Technostalgia

BBC Micro

Ahhhhh, Technostalgia. This evening I pulled out a box from the attic. It contained an instance of the first computer I ever used. A trusty BBC B+ Micro and a whole pile of mods to go with it. What a fabulous piece of kit. Robust workhorse, Econet local-area-networking built-in (but no modem, how forward-thinking!), and a plethora of expansion ports. My admiration of this hardware is difficult to quantify but I wasted years of my life learning how to hack about with it, both hardware and software.

The BBC Micro taught me in- and out- of the classroom. My primary school had one in each classroom and, though those might have been the ‘A’ or ‘B’ models, I distinctly remember one BBC Master somewhere in the school. Those weren’t networked but I remember spraining a thumb in the fourth year of primary school and being off sports for a few weeks. That’s when things really started happening. I taught myself procedural programming using LOGO. I was 10 – a late starter compared to some. I remember one open-day the school borrowed (or dusted off) a turtle

BBC Buggy (Turtle)

Brilliant fun, drawing ridiculous spirograph-style patterns on vast sheets of paper.

When I moved up to secondary school my eyes were opened properly. The computer lab was pretty good too. Networked computers. Fancy that! A network printer and a network fileserver the size of a… not sure what to compare it with – it was a pretty unique form-factor – about a metre long, 3/4 metre wide and about 20cm deep from memory (but I was small back then). Weighed a tonne. A couple of 10- or 20MB Winchesters in it from what I recall. I still have the master key for it somewhere! My school was in Cambridge and had a couple of part-time IT teacher/administrators who seemed to be on loan from SJ Research. Our school was very lucky in that regard – we were used as a test-bed for a bunch of network things from SJ Research, as far as I know a relative of Acorn. Fantastic kit only occasionally let down by the single, core network cable slung overhead between two buildings.

My first experience of Email was using the BBC. We had an internal mail system *POST which was retired after a while, roughly when ARBS left the school I think. I wrote my own MTA back then too, but in BASIC – I must have been about 15 at the time. For internet mail the school had signed up to use something called Interspan which I later realised must have been some sort of bridge to Fidonet or similar.

Teletext Adapter

We even had a networked teletext server which, when working, downloaded teletext pages to the LAN and was able to serve them to anyone who requested them. The OWUKWW – One-way-UK-wide-web! The Music department had a Music 5000 Synth which ran a language called Ample. Goodness knows how many times we played Axel-F on that. Software/computer-programmable keyboard synth – amazing.

Around the same time I started coding in 6502 and wrote some blisteringly fast conversions of simple games I’d earlier written in BASIC. I used to spend days drawing out custom characters on 8×8 squared exercise books. I probably still have them somewhere, in another box in the attic.

6502 coprocessor

Up until this point I’d been without a computer at home. My parents invested in our first home computer. The Atari ST. GEM was quite a leap from the BBC but I’d seen similar things using (I think) the additional co-processors – either the Z80- or the 6502 co-pro allowed you to run a sort of GEM desktop on the Beeb.

My memory is a bit hazy because then the school started throwing out the BBCs and bringing in the first Acorn Archimedes machines. Things of beauty! White, elegant, fast, hot, with a (still!) underappreciated operating system, high colour graphics, decent built-in audio and all sorts of other goodies. We had a Meteosat receiver hooked up to one in the geography department, pulling down WEFAX transmissions. I *still* haven’t got around to doing that at home, and I *still* want to!

Acorn A3000 Publicity Photo
Atari STE Turbo Pack

The ST failed pretty quickly and was replaced under warranty with an STE. Oh the horror – it was already incompatible with several games, but it had a Blitter chip ready to compete with those bloody Amiga zealots. Oh Babylon 5 was rendered on an Amiga. Sure, sure. But how many thousands of hit records had been written using Cubase or Steinberg on the Atari? MIDI – there was a thing. Most people now know MIDI as those annoying, never-quite-sounding-right music files which autoplay, unwarranted, on web pages where you can’t find the ‘mute’ button. Even that view is pretty dated.

Back then MIDI was a revolution. You could even network more than one Atari using it, as well as all your instruments of course. The STE was gradually treated to its fair share of upgrades – 4MB ram and a 100MB (SCSI, I think) hard disk, a “StereoBlaster” cartridge even gave it DSP capabilities for sampling. Awesome. I’m surprised it didn’t burn out from all the games my brothers and I played. I do remember wrecking *many* joysticks.

Like so many others I learned more assembler, 68000 this time, as I’d done with the BBC, by typing out pages and pages of code from books and magazines, spending weeks trying to find the bugs I’d introduced, checking and re-checking code until deciding the book had typos, but GFA Basic was our workhorse. My father had also started programming in GFA, and still did do until about 10 years ago when the Atari was retired.

Then University. First term, first few weeks of first term. I blew my entire student grant, £1400 back then, on my first PC. Pentium 75, 8MB RAM, a 1GB disk and, very important back then, a CD-ROM drive. A Multimedia PC!
It came with Windows 3.11 for Workgroups but with about 6 weeks of work was dual boot with my first Linux install. Slackware.

That one process, installing Slackware Linux with only one book “Que: Introduction to UNIX” probably taught me more about the practicalities of modern operating systems than my entire 3-year BSc in Computer Science (though to be fair, almost no theory of course). I remember shuttling hundreds of floppy disks between my room in halls and the department and/or university computer centre. I also remember the roughly 5% corruption rate and having to figure out the differences between my lack of understanding and buggered files. To be perfectly honest things haven’t changed a huge amount since then. It’s still a daily battle between understanding and buggered files. At least packaging has improved (apt; rpm remains a backwards step but that’s another story) but basically everything’s grown faster. At least these days the urge to stencil-spray-paint my PC case is weaker.

So – how many computers have helped me learn my trade? Well since about 1992 there have been five of significant import. The BBC Micro; the Acorn Archimedes A3000; the Atari ST(E); the Pentium 75 and my first Apple Mac G4 powerbook. And I salute all of them. If only computers today were designed and built with such love and craft. *sniff*.

Required Viewing:

  • Micro Men
  • The Pirates of Silicon Valley

Pseudo-VPN stuff with SSH

Firstly, there are *lots* of ways to do this. This is one way.

Secondly, poking holes in your corporate network is occasionally frowned upon and may contravene your workplace Acceptable Use Policy or equivalent. If you have a VPN solution (HTTPS, L2TP, or whatever) which works on everything you need, then I shouldn’t need to tell you to use that instead.

Anyway…

At home, on the end of my DSL line I have a PC running Linux.

At work I have lots of PCs running Linux.

Sometimes I’m using a random machine and/or a platform unsupported by my corporate VPN and I want to connect to work without using the (recommended) HTTPS VPN or (complicated) L2TP. So I turn to a trusty source of cool networky stuff: SSH.

Importantly, SSH understands how to be a SOCKS server. This allows applications which understand SOCKS (most Windows stuff for example) to redirect all their traffic over SSH without the addition of a proxy server like Squid on the corporate end.

So, how do you set it up? It’s fairly easy:

1. Set up the work-to-home connection:

user@work:~$ while [ 1 ]; do ssh -NR20000:localhost:22 user@home.net; done

2. Set up the laptop-to-home connection:

user@laptop:~$ ssh -L15000:localhost:20000 user@home.net

3. Set up the laptop-to-work connection:

user@laptop:~$ ssh -D15001 localhost -p 15000

If you’re at home and your “other” machine is on the same network as your home server you can be a bit more adventurous and do the following:

1. set GatewayPorts yes in your sshd_config

2. Set up the work-to-home connection, where home_ip is the IP of your home server on your internal network:

user@work:~$ while [ 1 ]; do ssh -NRhome_ip:15000:localhost:22 user@home.net; done

3. Set up the laptop-to-work connection:

user@laptop:~$ ssh -D15001 home_ip -p 15000

Passwordless authentication can be configured by setting up your ssh host keys correctly.

In both scenarios above, SOCKS-aware applications can be configured with server as “localhost” and port as “15001”. For non-SOCKS-aware applications, you can generally get away with using tsocks.

You’ll also notice that step (1) needs bootstrapping while you’re on the corporate network. Persuade someone to su to you, or do it while you’re in the office one day.

Generally you also want to reduce the possibility of your work-to-home connection failing, so run it in screen, or in a nohup script or use something like autossh or rstunnel to bring it back up for you.

Don’t forget you’ll also need to open appropriate holes in your home firewall, generally some sort of NAT, PAT, or DMZ settings to allow incoming SSH (TCP, port 22) to be forwarded to your home server.

Update 2010-06-30 17:57
It’s worth mentioning that if you don’t have a static IP on your home DSL line that you’ll need to use a dynamic DNS service (like DynDNS) to keep a static name for your dynamic IP. Personally I do other stuff with Linode so I’ve set something cool up using their web-service API.

Bookmarks for June 14th through June 28th

These are my links for June 14th through June 28th:

Bookmarks for June 8th through June 14th

These are my links for June 8th through June 14th:

Adventures in UTF-8

I think I’m very nearly at the verge of beginning to understand UTF-8.

Internal UTF-8 string, encoded
Wrong:

sentinel:~ rmp$ perl -MHTML::Entities -e 'print encode_entities("°")'
°

Right:

sentinel:~ rmp$ perl -Mutf8 -MHTML::Entities -e 'print encode_entities("°")'
°

External UTF-8 input, encoded
Wrong:

sentinel:~ rmp$ echo "°" | perl -MHTML::Entities -e 'print encode_entities(<>)'
&Acirc;&deg;

Right:

sentinel:~ rmp$ echo "°" | perl -MHTML::Entities -e 'binmode STDIN, ":utf8"; print encode_entities(<>)'
&deg;

External UTF-8 string, as UTF-8 (unencoded)
Wrong:

sentinel:~ rmp$ echo "°" | perl -e 'binmode STDIN, ":utf8"; print <>'
?

Right:

sentinel:~ rmp$ echo "°" | perl -e 'binmode STDIN, ":utf8"; 
binmode STDOUT, ":utf8"; print <>'
°

External Input – Encoding after-the-fact
Wrong:

sentinel:~ rmp$ echo "°" | perl -Mutf8 -e '$in=<>; utf8::upgrade($in);
binmode STDOUT, ":utf8"; print $in'
°

Wrong:

sentinel:~ rmp$ echo "°" | perl -Mutf8 -e '$in=<>; utf8::encode($in);
binmode STDOUT, ":utf8"; print $in'
°

Wrong:

sentinel:~ rmp$ echo "°" | perl -Mutf8 -e '$in=<>; utf8::downgrade($in); 
binmode STDOUT, ":utf8"; print $in'
°

Right:

sentinel:~ rmp$ echo "°" | perl -Mutf8 -e '$in=<>; utf8::decode($in);
binmode STDOUT, ":utf8"; print $in'
°

Bookmarks for May 13th through June 4th

These are my links for May 13th through June 4th:

Generating MSCACHE & NTLM hashes using Perl

I’ve been doing a lot of tinkering recently whilst working on the revised rainbowcracklimited.com website. Naturally it uses Perl on the back end so I’ve had to find out how to make Windows-style hashes of various types using largely non-native means.

On the whole I’ve been able to make good use of the wealth of CPAN modules – Digest::MD4, Digest::MD5, Digest::SHA and Authen::Passphrase but for one reason and another I’ve wanted to find out how to make NTLM and MSCACHE hashes “by-hand”. It turns out this is pretty easy:

NTLM is just a MD4 digest of the password in Unicode, or to be specific utf16 2-byte characters + surrogates:

perl -M"Unicode::String latin1" -M"Digest::MD4 md4_hex" -e 'print md4_hex(latin1("cheese")->utf16le),"\n"'

MSCACHE is a little bit more fiddly as it also encodes the Unicode username as well:

perl -M"Unicode::String latin1" -M"Digest::MD4 md4_hex" -e 'print md4_hex(latin1("cheese")->utf16le . latin1(lc "Administrator")->utf16le),"\n"'

Bookmarks for April 30th through May 11th

These are my links for April 30th through May 11th:

Bookmarks for April 25th through April 29th

These are my links for April 25th through April 29th: