Posted by avsm
Sat, 31 Jul 2004 20:59:50 GMT
I finally put up a page for Blueproxy, a handy Bluetooth RFCOMM to TCP proxy server I've been using in most of the Bluetooth hacking I've been doing for my research recently.
The current pain with Bluetooth hacking is the splintered API situation. Linux has one stack, Bluez, which it integrated into 2.4, but it's incredibly badly documented (as far as I can tell, pretty much not at all). FreeBSD has the best stack I've seen yet, based on Netgraph. MacOS X has a half-baked effort, involving setting up stuff using a GUI; however it looks like Tiger will improve this. And of course the wait continues for the Bluetooth stack in Windows XP Service Pack 2 (I refuse to risk installing it at least until it's officially released!).
The FreeBSD stack is the clear winner out of all these, with decent documentation, fewer bugs, and the most familiar interface (for example, an /etc/bluetooth/hosts file). I'm quite keen to port it to OpenBSD when I get a chance, but it does first require removing the Netgraph portions. It also looks like NetBSD has the beginnings of some code to handle the Bluetooth HCI layer; wonder how that will pan out.
Posted in hacking | no comments
Posted by avsm
Thu, 29 Jul 2004 08:53:48 GMT
The amount of spam sent to Recoil accounts has dramatically sprung
up over the last few years, sending the machine loads skyrocketing
accordingly. Luckily, we're running
OpenBSD, which added a fun
tool called
spamd(8)
a couple of releases ago.
It's activated by tracking IP addresses of known
spammers from blacklists like Spamhaus,
and redirecting them to the spam daemon via pf rules. Once the mail reaches spamd, it "tarpits"
it by dropping its TCP send and receive buffers to a very small value,
encouraging the spammers and virii to (slowly) send their malware on. If they
ever do reach the end of their data, it then rejects it with a temporary
failure - costing the spammers more resourcs if they decide to retransmit it.
The load has dropped quite a bit since I activated this filtering; it seems
to help against some of the latest worms quite a lot, which just
connect to port 25, spew off a buffer-overflow attempt, and repeat this
once every few seconds. Since spamd, things take a bit longer though!
quick spamd: 221.2.232.138: connected (9/9), lists: spamhaus
quick spamd: 221.2.232.138: disconnected after 431 seconds. lists: spamhaus
Very satisfying. I did play with the greylisting mode of spamd as well, but it wasn't quite as successful as some valid mail sites such as EDAS (bless its underwhelming soul) take five days to send conference paper rejections into a greylisted system. Public whitelists do exist, but I think I'll wait a while and see if things mature a little more first.
Posted in net, hacking | no comments
Posted by avsm
Sun, 25 Jul 2004 22:46:49 GMT
I used to do an awful lot of PHP hacking, but over the last few years, the boring gods of security and correctness have snared me, leaving me frustrated with the effort and resources required to create and maintain dynamic web content.
So I've converted my site over to static HTML, and started switching our main web-servers to use thttpd instead of Apache. The performance difference has been absolutely staggering, as the humble hardware behind fork.recoil.org managed to survive a slashdotting and mentions on opengl.org (for the latest release of OpenFX) without breaking a sweat.
thttpd is great; it uses the BSD kqueue(3) kernel event mechanism, and is single-threaded (removing the endearing fork-bomb effect Apache has when hit by a burst of traffic). There are quite a few good programs to help generate static content as well; my new blogging tool of choice is blosxom, which fits into the UNIX way of doing things absolutely perfectly.
Posted in recoil, hacking | no comments
Posted by avsm
Sun, 02 May 2004 21:45:00 GMT
My 15" AluBook had white spots, but I wasn't Too Lazy To Phone Apple! Not updated the blog for ages, will resolve to be better about this...
Posted in computers | no comments
Posted by avsm
Mon, 24 Nov 2003 18:12:00 GMT
Just passed my first year PhD viva, with very friendly advice from Prof. Andy Hopper and my supervisor Tim Harris. General criticism is that I'm too unfocused, which is an accusation that is all too true :-)
What else? Been working away, the Ubicomp 2003 paper went down pretty well, Seattle was a lot of fun, and Cambridge is even more fun right now. I bought a new 15" Titanium PowerBook, but its developed the infamous white spots - argh! Anand's wedding is rapidly approaching, so gotta sort myself out for that (a visa to get into India would be a good start). Times are busy. Fun though... can't argue with the PhD lifestyle compared to being stuck on a plane every morning at 7am (although I do miss real Italian breakfasts...)
Posted in research, cambridge | no comments
Posted by avsm
Fri, 29 Aug 2003 18:55:00 GMT
Ah well, just finished cleaning up my desk at Fraser Research - it's been a lot of fun here! From rafting on the Delaware to supping fine Brazilian cuisine in New York, and of course most excellent drinks from Small World Coffee. But it'll be nice to get back to Cambridge for the regular Sunday afternoon ostrich burgers as well :-)
Posted in usa, princeton | no comments
Posted by avsm
Thu, 07 Aug 2003 23:22:00 GMT
In what could be a silly move, I stumbled across the Friendster web-site, and joined up. It works on the famous six degrees of separation principle, which means that it takes very few hops to know someone else in the world.
Imagine my amusement when it turns out that Nick is already a member ... I should have guessed :-) If you join up, do invite me - I'm really curious to see how this network works out. They seem to be "good guys" and promise not to use the information they collect for nefarious purposes.
Posted in net | no comments
Posted by avsm
Thu, 31 Jul 2003 17:47:00 GMT
... since I've figured out what to submit for my thesis proposal :-)
I'm going to argue that language research has failed to make life easier for operating systems developers, and that there is a requirement for real high-level languages to make the structure of operating systems fundamentally better by use of type-safety and other such things that have been around for a very long time. The topic leaves me with plenty of breathing room to wander around playing with OCaml, GHC, and also work on the ideas of better web languages with Scotty and Sharpy.
I committed the privilege separated syslog daemon to the OpenBSD repository as well; it proved a lot harder than I expected (Theo de Raadt gave me an awful lot of help with it), so that's another area to think about ...
Posted in research, cambridge | no comments
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