I fjor sommer lagde jeg en
+offentlig
+tilgjengelig SQL-database over offentlig anbud basert på skraping
+av HTML-data fra Doffin. Den har stått og gått siden da, og har nå
+ca. 28000 oppføringer. Jeg oppdaget da jeg tittet innom at noen
+oppføringer var ikke blitt med, antagelig på grunn av at de fikk
+tildelt sekvensnummer i Doffin en godt stund før de ble publisert,
+slik at min nettsideskraper som fortsatte skrapingen der den slapp
+sist ikke fikk dem med seg. Jeg har fikset litt slik at skraperen nå
+ser litt tilbake i tid for å se om den har gått glipp av noen
+oppføringer, og har skrapet på nytt fra midten av september 2013 og
+fremover. Det bør dermed bli en mer komplett database for kommende
+måneder. Hvis jeg får tid skal jeg forsøke å skrape "glemte" data fra
+før midten av september 2013, men tør ikke garantere at det blir
+prioritert med det første.
+
+
Men målet med denne bloggposten er å vise hvordan denne
+Doffin-databasen kan brukes og integreres med en RSS-leser, slik at en
+kan la datamaskinen holde et øye med Doffin-annonseringer etter
+nøkkelord. En kan lage sitt eget søk ved å besøke
+API-et
+hos Scraperwiki, velge format rss2 og så legge inn noe ala dette i
+"query in SQL":
+
+
+select title, scrapedurl as link, abstract as description,
+ publishdate as pubDate from 'swdata'
+ where abstract like '%linux%' or title like '%linux%'
+ order by seq desc limit 20
+
+
+
Dette vil søke opp alle anbud med ordet linux i oppsummering eller
+tittel. En kan lage mer avanserte søk hvis en ønsker det. URL-en som
+dukker opp nederst på siden kan en så gi til sin RSS-leser (jeg bruker
+akregator selv), og så automatisk få beskjed hvis det dukker opp anbud
+med det aktuelle nøkkelordet i teksten. Merk at kapasiteten og
+ytelsen hos Scraperwiki er begrenset, så ikke be RSS-leseren hente ned
+oftere enn en gang hver dag.
+
+
Du lurer kanskje på hva slags informasjon en kan få ut fra denne
+databasen. Her er to RSS-kilder, med søkeordet
+"linux",
+søkeordet
+"fri
+programvare"
+og søkeordet
+"odf".
+Det er bare å søke på det en er interessert i. Kopier gjerne
+datasettet og sett opp din egen tjeneste hvis du vil gjøre mer
+avanserte søk. SQLite-filen med Doffin-oppføringer kan lastes med fra
+Scraperwiki for de som vil grave dypere.
Today NUUG and Hackeriet announced
+our
+plans to join forces and create a wireless community network in
+Oslo. The workshop to help people get started will take place
+Thursday 2013-11-28, but we already are collecting the geolocation of
+people joining forces to make this happen. We have
+9
+locations plotted on the map, but we will need more before we have
+a connected mesh spread across Oslo. If this sound interesting to
+you, please join us at the workshop. If you are too impatient to wait
+15 days, please join us on the IRC channel
+#nuug on irc.freenode.net
+right away. :)
Continuing my research into mesh networking, I was recommended to
+use TP-Link 3040 and 3600 access points as mesh nodes, and the pair I
+bought arrived on Friday. Here are my notes on how to set up the
+MR3040 as a mesh node using
+OpenWrt.
+
+
I started by following the instructions on the OpenWRT wiki for
+TL-MR3040,
+and downloaded
+the
+recommended firmware image
+(openwrt-ar71xx-generic-tl-mr3040-v2-squashfs-factory.bin) and
+uploaded it into the original web interface. The flashing went fine,
+and the machine was available via telnet on the ethernet port. After
+logging in and setting the root password, ssh was available and I
+could start to set it up as a batman-adv mesh node.
+
+
I started off by reading the instructions from
+Wireless
+Africa, which had quite a lot of useful information, but
+eventually I followed the recipe from the Open Mesh wiki for
+using
+batman-adv on OpenWrt. A small snag was the fact that the
+opkg install kmod-batman-adv command did not work as it
+should. The batman-adv kernel module would fail to load because its
+dependency crc16 was not already loaded. I
+reported the bug to
+the openwrt project and hope it will be fixed soon. But the problem
+only seem to affect initial testing of batman-adv, as configuration
+seem to work when booting from scratch.
+
+
The setup is done using files in /etc/config/. I did not bridge
+the Ethernet and mesh interfaces this time, to be able to hook up the
+box on my local network and log into it for configuration updates.
+The following files were changed and look like this after modifying
+them:
The mesh node is now operational. I have yet to test its range,
+but I hope it is good. I have not yet tested the TP-Link 3600 box
+still wrapped up in plastic.
The last few days I have been experimenting with
+the
+batman-adv mesh technology. I want to gain some experience to see
+if it will fit the
+Freedombox project, and together with my neighbors try to build a
+mesh network around the park where I live. Batman-adv is a layer 2
+mesh system ("ethernet" in other words), where the mesh network appear
+as if all the mesh clients are connected to the same switch.
+
+
My hardware of choice was the Linksys WRT54GL routers I had lying
+around, but I've been unable to get them working with batman-adv. So
+instead, I started playing with a
+Raspberry Pi, and tried to
+get it working as a mesh node. My idea is to use it to create a mesh
+node which function as a switch port, where everything connected to
+the Raspberry Pi ethernet plug is connected (bridged) to the mesh
+network. This allow me to hook a wifi base station like the Linksys
+WRT54GL to the mesh by plugging it into a Raspberry Pi, and allow
+non-mesh clients to hook up to the mesh. This in turn is useful for
+Android phones using the Serval
+Project voip client, allowing every one around the playground to
+phone and message each other for free. The reason is that Android
+phones do not see ad-hoc wifi networks (they are filtered away from
+the GUI view), and can not join the mesh without being rooted. But if
+they are connected using a normal wifi base station, they can talk to
+every client on the local network.
+
+
To get this working, I've created a debian package
+meshfx-node
+and a script
+build-rpi-mesh-node
+to create the Raspberry Pi boot image. I'm using Debian Jessie (and
+not Raspbian), to get more control over the packages available.
+Unfortunately a huge binary blob need to be inserted into the boot
+image to get it booting, but I'll ignore that for now. Also, as
+Debian lack support for the CPU features available in the Raspberry
+Pi, the system do not use the hardware floating point unit. I hope
+the routing performance isn't affected by the lack of hardware FPU
+support.
+
+
To create an image, run the following with a sudo enabled user
+after inserting the target SD card into the build machine:
Booting with the resulting SD card on a Raspberry PI with a USB
+wifi card inserted should give you a mesh node. At least it does for
+me with a the wifi card I am using. The default mesh settings are the
+ones used by the Oslo mesh project at Hackeriet, as I mentioned in
+an
+earlier blog post about this mesh testing.
+
+
The mesh node was not horribly expensive either. I bought
+everything over the counter in shops nearby. If I had ordered online
+from the lowest bidder, the price should be significantly lower:
+
+
+
+
Supplier
Model
NOK
+
Teknikkmagasinet
Raspberry Pi model B
349.90
+
Teknikkmagasinet
Raspberry Pi type B case
99.90
+
Lefdal
Jensen Air:Link 25150
295.-
+
Clas Ohlson
Kingston 16 GB SD card
199.-
+
Total cost
943.80
+
+
+
+
Now my mesh network at home consist of one laptop in the basement
+connected to my production network, one Raspberry Pi node on the 1th
+floor that can be seen by my neighbor across the park, and one
+play-node I use to develop the image building script. And some times
+I hook up my work horse laptop to the mesh to test it. I look forward
+to figuring out what kind of latency the batman-adv setup will give,
+and how much packet loss we will experience around the park. :)
Back in 2010, I created a Perl library to talk to
+the Spykee robot
+(with two belts, wifi, USB and Linux) and made it available from my
+web page. Today I concluded that it should move to a site that is
+easier to use to cooperate with others, and moved it to github. If
+you got a Spykee robot, you might want to check out
+the
+libspykee-perl github repository.
Wireless mesh networks are self organising and self healing
+networks that can be used to connect computers across small and large
+areas, depending on the radio technology used. Normal wifi equipment
+can be used to create home made radio networks, and there are several
+successful examples like
+Freifunk and
+Athens Wireless Metropolitan Network
+(see
+wikipedia
+for a large list) around the globe. To give you an idea how it
+work, check out the nice overview of the Kiel Freifunk community which
+can be seen from their
+dynamically
+updated node graph and map, where one can see how the mesh nodes
+automatically handle routing and recover from nodes disappearing.
+There is also a small community mesh network group in Oslo, Norway,
+and that is the main topic of this blog post.
+
+
I've wanted to check out mesh networks for a while now, and hoped
+to do it as part of my involvement with the NUUG member organisation community, and
+my recent involvement in
+the Freedombox project
+finally lead me to give mesh networks some priority, as I suspect a
+Freedombox should use mesh networks to connect neighbours and family
+when possible, given that most communication between people are
+between those nearby (as shown for example by research on Facebook
+communication patterns). It also allow people to communicate without
+any central hub to tap into for those that want to listen in on the
+private communication of citizens, which have become more and more
+important over the years.
+
+
So far I have only been able to find one group of people in Oslo
+working on community mesh networks, over at the hack space
+Hackeriet at Husmania. They seem to
+have started with some Freifunk based effort using OLSR, called
+the Oslo
+Freifunk project, but that effort is now dead and the people
+behind it have moved on to a batman-adv based system called
+meshfx. Unfortunately the wiki
+site for the Oslo Freifunk project is no longer possible to update to
+reflect this fact, so the old project page can't be updated to point to
+the new project. A while back, the people at Hackeriet invited people
+from the Freifunk community to Oslo to talk about mesh networks. I
+came across this video where Hans Jørgen Lysglimt interview the
+speakers about this talk (from
+youtube):
+
+
+
+
I mentioned OLSR and batman-adv, which are mesh routing protocols.
+There are heaps of different protocols, and I am still struggling to
+figure out which one would be "best" for some definitions of best, but
+given that the community mesh group in Oslo is so small, I believe it
+is best to hook up with the existing one instead of trying to create a
+completely different setup, and thus I have decided to focus on
+batman-adv for now. It sure help me to know that the very cool
+Serval project in Australia
+is using batman-adv as their meshing technology when it create a self
+organizing and self healing telephony system for disaster areas and
+less industrialized communities. Check out this cool video presenting
+that project (from
+youtube):
+
+
+
+
According to the wikipedia page on
+Wireless
+mesh network there are around 70 competing schemes for routing
+packets across mesh networks, and OLSR, B.A.T.M.A.N. and
+B.A.T.M.A.N. advanced are protocols used by several free software
+based community mesh networks.
+
+
The batman-adv protocol is a bit special, as it provide layer 2
+(as in ethernet ) routing, allowing ipv4 and ipv6 to work on the same
+network. One way to think about it is that it provide a mesh based
+vlan you can bridge to or handle like any other vlan connected to your
+computer. The required drivers are already in the Linux kernel at
+least since Debian Wheezy, and it is fairly easy to set up. A
+good
+introduction is available from the Open Mesh project. These are
+the key settings needed to join the Oslo meshfx network:
+
+
+
Setting
Value
+
Protocol / kernel module
batman-adv
+
ESSID
meshfx@hackeriet
+
Channel / Frequency
11 / 2462
+
Cell ID
02:BA:00:00:00:01
+
+
+
The reason for setting ad-hoc wifi Cell ID is to work around bugs
+in firmware used in wifi card and wifi drivers. (See a nice post from
+VillageTelco about
+"Information
+about cell-id splitting, stuck beacons, and failed IBSS merges!
+for details.) When these settings are activated and you have some
+other mesh node nearby, your computer will be connected to the mesh
+network and can communicate with any mesh node that is connected to
+any of the nodes in your network of nodes. :)
+
+
My initial plan was to reuse my old Linksys WRT54GL as a mesh node,
+but that seem to be very hard, as I have not been able to locate a
+firmware supporting batman-adv. If anyone know how to use that old
+wifi access point with batman-adv these days, please let me know.
+
+
If you find this project interesting and want to join, please join
+us on IRC, either channel
+#oslohackerspace
+or #nuug on
+irc.freenode.net.
+
+
While investigating mesh networks in Oslo, I came across an old
+research paper from the university of Stavanger and Telenor Research
+and Innovation called
+The
+reliability of wireless backhaul mesh networks and elsewhere
+learned that Telenor have been experimenting with mesh networks at
+Grünerløkka in Oslo. So mesh networks are also interesting for
+commercial companies, even though Telenor discovered that it was hard
+to figure out a good business plan for mesh networking and as far as I
+know have closed down the experiment. Perhaps Telenor or others would
+be interested in a cooperation?
+
+
Update 2013-10-12: I was just
+told
+by the Serval project developers that they no longer use
+batman-adv (but are compatible with it), but their own crypto based
+mesh system.
It starts 10:00 and continue until late evening. Everyone is
+welcome, and there is no fee to participate. There is on the other
+hand limited space, and only room for 30 people. Please put your name
+on the event
+wiki page if you plan to join us.
Cranor, L.F. og Cytron, R.K., "Design and Implementation of a
Security-Conscious Electronic Polling System" Washington University
Computer Science Technical Report WUCS-96-02. February 1996
-http://www.cs.wustl.edu/cs/techreports/1996/wucs-96-02.ps.Z
Security Analysis of the Diebold AccuVote-TS Voting Machine av
Ariel J. Feldman, J. Alex Halderman, og Edward
W. Felten. http://itpolicy.princeton.edu/voting/
-http://coblitz.codeen.org:3125/itpolicy.princeton.edu/voting/videos/ts-voting.wmv
Styreframlegg om elektronisk votering ved
-UiO. http://www.admin.uio.no/kollegiet/moter/kart_prot2006/5/protokoll.xml
-http://www.admin.uio.no/kollegiet/moter/kart_prot2006/5/vsak-14.pdf
-http://www.admin.uio.no/kollegiet/moter/kart_prot2006/5/vsak-14-vedlegg.pdf
Elektroniske valg - muligheter, problemer og noen løsninger
Semesteroppgave i STV620 - Demokratiske valg
-http://www.afin.uio.no/forskning/notater/4_01.html