JanusPA - A hardware Privacy Adapter using Tor
dante at virtualblueness.net
Tue Dec 23 23:28:49 UTC 2008
(Sorry I sent my second post before I read your response to my first.)
The Linksys WRT54g has a 125-MHz Broadcom BCM4710 cpu with 16MB ram.
The performance is poor, but it does work. It eventually runs out of
memory, at which point, I can restart the router, rerun the hack
scripts, etc. It is fun to play with, but too annoying for practical
use. I haven't run it for a while, but I'm going to again so I can get
a better feel for its limits.
The boards I wrote about in my second post should be able to handle the
loads for a tor client (and perhaps a small tor relay). In my work with
tor-ramdisk (tor in a micro linux ramdisk distro), I did try a 400 MHz
i686 cpu with 128 MB ram as a tor client --- no problems (I used one of
our lab's thin clients - HP Compaq t5135). The 64 MB of ram set aside
for the ramdisk was able to accomodate the cached files in /var/lib/tor
which grew to about 27MB after many days of usage. The t5135 is
comparable to the RB433 to RB433AH router boards I quoted earlier.
As a relay or exit node, cpu/ram usage grows with BandwidthRate, but I
don't know of any good studies. The only data I have are far outside of
the realm of what you are trying to do, but we can scale it down: node
"simba" runs tor-ramdisk, but it has 4 x 2.5 GHz i686 and 4 GB of ram.
Its a relay only node with BandwidthRate 150 KB/s, but it could handle a
lot more bandwidth. Its cpu usage is typically below 5%. Scaling down
this means 5% of 4x2500 MHz = 500 MHz, again in the range above. The
ram is total overkill.
I know my information is not systematic, but I hope it helps.
Kyle Williams wrote:
> Hi Tony,
> I'm curious as to how well it performed. How much RAM and CPU did the
> Linksys WRT54G have?
> I was worried that the linksys/netgear/dlink brands would not be that fast.
> I could be wrong though...
> Ah, so it did run out of memory. That's one of the two major problems I
> thought would happen with a "brand name" router.
> I ran a Tor server for about 3 to 4 days to try and get a good baseline of
> performance. Do you have any performance stats?
> If so, I would love to see them.
> - Kyle
> On Tue, Dec 23, 2008 at 7:00 AM, dante <dante at virtualblueness.net> wrote:
>> Hi Kyle,
>> Very nice work.
>> You might be interested in something I did a little while ago. I got a
>> tor server running on a wireless Linksys WRT54g router. This allows me
>> to use tor at home with my laptops wirelessly.
>> Here's a quick howto since I never published on my site:
>> 1) Get a MIPS I (little endian) environment up. I used qemu and
>> installed debian-mipsel. I started with the ramdisk image
>> mipsel-test-0.2.tar.gz from http://bellard.org/qemu/download.html and
>> bootstrapped into a fully functional debian system.
>> 2) I compiled tor statically linked. (CFLAGS="-static" ./configure)
>> 3) I got into my linksys using "Linux on WRTG54g" ...
>> 4) I used ftpget to upload tor, configure and start it up.
>> It works fine, but you run out of memory fast because you have to use
>> ramdisk to store tor's cache files.
>> Tony Basile
>> Kyle Williams wrote:
>>> If anyone is seriously thinking about a good hardware based solution for
>>> Tor, I'd buy the gumstix now. In fact, I just bought a couple more just
>>> case mine breaks. I'll have the source code up withing a week, two tops
>>> FULL documentation will take about a bit longer to get done.
>>> Well, that's about it. Feedback is welcome.
>>> Best Regards,
>>> PS. Happy Holidays!
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