Regulatory control kai wireless drivers...

[Nick Kossifidis]

Hello ;-)

Kata kairous sas exw anaferei thn prothesh ths omadas twn developers
pou asxoleitai me tous wireless drivers sto Linux na parexoume kapoiou
eidous regulatory control, dhladh na kleidwnoume by default kapoia
kanalia pou den provlepetai h xrhsh tous apo ton nomo ana xwra kathws
kai na periorisoume thn isxy ekpomphs omoiws sta plaisia tou nomou. O
vasikos logos pou theloume kati tetoio einai gia na proselkysoume
perissoterous vendors na mas dwsoun specs gia tis kartes tous kathoti
oi perissoteroi fovountai oti emas aplws mas endiaferei na doulevoun
oi kartes sto full kai oxi na diasfalizoume th swsth xrhsh tous. An
kapoios pou xrhsimopoiei Linux poiastei na ekpempei ektws nomikwn
plaisiwn xwris sxetikh adeia, ousiastika o chip vendor h o OEM vendor
kindynevoun na pathoun megalh zhmia kathoti akyrwnetai to declaration
of conformity pou exoun ypograpsei kai ousiastika to proion tous na
aposyrthei ap' thn agora h meros ayths. Epishs me ayto ton tropo
epitrepoume se atoma/etairies pou theloun na xrhsimopoihsoun to Linux
gia emporikous skopous (px xrhsimopoiwntas OpenWRT pou einai poly
diadedomeno) na exoun allo ena kinhtro. Telos yparxoun outws h allws
kapoioi periorismoi logw hw, afou oi kartes exoun sxediastei na
ekpempoun se sygekrimena eyrh syxnwthtwn kai me sygekrimenh max isxy,
opote an kapoios ekpempsei ektws oriwn kai me megalh isxy kindynevei
na katastrepsei thn karta h na exei poly kako performance (sygekrimena
gia tis Atheros exoume periptwsh pou kapoios katestrepse ton pre
amplifier vazontas thn karta na ekpempsei sta 6Ghz, enw otan h karta
ekpempei se full isxy, ola ta rates apo 18Mb kai epanw synithws exoun
corrupted spectral mask kai ekpempontai skoupidia).

Ap' thn allh omws den theloume se kamia periptwsh na efarmosoume
praktikes DRM, den theloume na apagoreysoume stous xrhstes tou Linux
na kanoun to otideipote me tis kartes tous, apla theloume na
prostateysoume toso aytous (afou mporei na ekpempoun ektws oriwn en
angoia tous shkwnontas px ena AP) oso kai to Linux apo tous diaforous
kakovoulous pou yparxoun trygyrw (giati yparxoun arketes etairies ekei
eksw pou einai etoimoi na mas th pesoun). Den theloume se kamia
periptwsh na "mas vgei to onoma" oti to Linux kai oi Linuxades
kseskizoun to fasma. Etsi katalhksame sthn ekshs ylopoihsh...

Exoume enan Central Regulatory Domain Agent (CRDA) o opoios trexei sto
userspace (o kwdikas edw ->
http://git.kernel.org/?p=linux/kernel/git/mcgrof/crda.git;a=tree)  kai
xrhsimopoiei mia binary database pou thn exoume kanei sign oi
developers tou kernel (vasika o kernel maintainer ek merous mas). H
database den einai tipote allo apo ena txt arxeio pou apla exei ginei
encrypted (mporeite na to deite edw ->
http://git.kernel.org/?p=linux/kernel/git/linville/wireless-regdb.git;a=blob;f=db.txt;hb=HEAD)
me to private key tou John kai o CRDA exei to public key. By default
loipon oloi xrhsimopoioun thn default database pou exoume kanei sign
kai egyomaste oti einai entaksei. An twra kapoios thelei na
xrhsimopoihsei diaforetikh database (eitai aytos einai etairia, eitai
distro, eitai o opoiosdhpote telos pantwn) mporei na ftiaksei to diko
tou db.txt, na to ypograpsei me to private key tou kai na valei to
public key tou ston CRDA tou. Tha mou peite ti nohma exei an mporei na
parakamfthei etsi eykola to regulatory control na agxonomaste ? Nomika
loipon an kapoios kanei ayth th douleia emeis den egyomaste gi' ayton
opote exei olh thn eythynh twn praksewn tou, etsi prostatevoume to
Linux kai oti ayto synepagetai. Einai san ayto pou kanei px h Mikrotik
pou se afhnei na anoikseis ola ta kanalia (an plhrwseis ennoeitai :P)
arkei na symfwniseis me to License (isa isa pou emeis to kanoume poio
ousiastika afou kaneis synithws den diavazei to license, otan omws tha
xreiastei na ftiaksei h na xrhsimopoihsei mia diaforetikh database
tote syneidhta tha kserei ti kanei).

Kati allo pou einai endiaferon einai pws kseroume pou vrisketai o
xrhsths h telos pantwn se poio regulatory domain vrisketai kathe
fora...

a) To prwto vhma einai na doume mhpws h karta exei kapou programmed
ayth th plhroforia (px. sthn EEPROM h hadcoded sto firmware)
b) An den yparxei ayth h plhroforia tote o xrhsths mporei na orisei th
xwra sthn opoia vrisketai (mesw tou iw -to kainourio ergaleio pou sto
mellon tha antikatastisei ta wireless tools- ki elpizw kai mesa ap'
ton NetworkManager)
d) Epishs yparxei to 802.11d ap' to opoio mporoume na paroume ayth th
plhroforia (an mas th dinei to AP) alla dystyxws den to ylopoioun
panta (kai akoma ki an to ylopoioun, oi perissoteroi -stokoi as mou
epitrapei o xarakthrismos- den mpainoun ston kopo na kanoun swsta
configure ta AP pou sthnoun), enw tha mporousame na xrhsimopoihsoume
ayth th plhroforia ap' ton SNMP (opou epishs omws oloi variountai na
kanoun swsta configure).

Koinws ap ta parapanw mono to a einai to sigouro gi' ayto kai einai to
default kai to "prwto se protimhsh" kai se kapoies periptwseis einai
kai locked (dhladh an yparxei ayto den proxwrame sta alla 2 ki apla
epitrepoume th xrhsh "world" domains pou praktika einai domains opou
nai men mporeis na xrhsimopoieis kapoia kanalia alla mono ws client
kai mono kanontas passive scan -dld kaneis sniff kai an yparxei kapoio
AP sto kanali tote mporeis na syndetheis epanw tou kanonika).

Edw -> http://wireless.kernel.org/en/developers/Regulatory
perigrafetai analytikotera h olh arxitektonikh.

Edw -> http://wireless.kernel.org/en/developers/Regulatory/statement
einai to public statement pou ypografoume oi developers gia na kanoume
gnwstes tis protheseis mas ston eksw kosmo (kai kyriws opws sas eipa
stous vendors kai fysika stous antistoixous foreis).

Twra yparxoun kapoies kartes pou exoun epipleon capabilities pera apo
to na ekpempoun se diafora ranges opws px. oi kartes pou ypostirizoun
diafora "turbo" modes kathws kai alles kartes (opws oi Atheros) pou
yposthrizoun diaforetiko spacing metaksy twn kanaliwn (dhladh mesa sta
epitrepta ranges exoume perissoteres diathesimes syxnothtes na
paiksoume) kai diaforetiko channel width (half/quarter rate/XR/turbo).
Parolo pou to regulation afora mono to eyros twn syxnothtwn kai to tx
power gia texnikous logous den symfairei by default na kanoume enable
tetoia features (vl. xrhsh mnhmhs, xronos scan klp), etsi syzhtagame
pws tha mporousame genikws na mporoume na kanoume enable ayta ta
features on demand afou fortwsei o driver. H protash mou pou telika
symfwnoun arketoi (metaksy twn opoiwn kai o John) einai na ftiaksoume
ena mhxanismo gia na mporoume na kanoume register channels runtime. Me
ayto ton tropo tha mporoume px. na kanoume register oles tis
endiameses syxnothtes ws extra kanalia (me noumera apo to 200 kai panw
px.) opws epishs kai gia kathe tetoio functionality na kanoume
register ena ksexwristo range apo kanalia (panta on demand, px otan o
xrhsths kanei enable ta half rate kanalia tha ginontai unregister ta
prohgoumena extra kanalia kai tha ginontai register ta kainouria me to
half rate flag set). To kathe kanali exei kapoia flags opou ekei tha
exoume kanei enable ta diafora features kai o driver tha dra analoga
(enw ta flags tha ginontai list sth lista me ta kanalia tou driver me
to iw). Einai mia prwth idea vevaia kai den exoume mpei se texnikes
leptomeries akoma (tha to syzhtisoume mallon sto epomeno summit) alla
to kalo einai oti yparxei diathesh gia kati tetoio.

Telos kapoia endiaferonta infos apo to development twn teleytaiwn mhnwn...

a) O ath5k apektise tx power support kai pleon mporeite na poiasete
kanonika mexri 27.5Mb afou ta rates panw ap' ta 18Mb pleon doulevoun,
syntoma o ath5k tha veltiwthei dramatika, eidika sto kommati tou phy
(edw na eyxaristhsw to ellak gia thn oikonomikh enisxysh, htan kati
pou tha ekana outws h allws alla opws kai na xei htan ena epipleon
kinhtro gia na doulepsw poio entatika -vevaia h sxolh paei peripatto
alla tha th palepsw kapws :P-).

b) O Jouni ekane submit mia seira apo patches pou kanoun enable ston
ath9k ta virtual ifs (opws ta VAPs ston MadWiFi alla pleon tha ginetai
na exete kai virtual STAs klp) enw eishgage kai mia nea texnikh opou
tha exoume virtual radios (ayto TA SPAEI) dhladh tha mporeite me mia
karta na eisaste syndedemenoi se APs pou paizoun se diaforetika
kanalia (proypothesh einai h karta na mporei na kanei grhgora switch
-kai an to epixeirhsete tha sas proteina na exete megalo beacon
interval sta APs-). Vevaia ayta mexri na ftasoun stous telikous
xrhstes tha parei arketos kairos (akoma oute oi prosthikes sto
cfg80211/nl80211 den exoun ginei, poso mallon sto iw -ennoeitai pws
den prokeitai na ginei kati tetoio me ta wireless tools, ayta
prospathoume na ta ksefortwthoume asap-).

c) Asxeto me wireless alla pleon to tux3 exei arxisei na doulevei
ikanopoihtika (kanan boot apo tux3 partition poly prosfata !) kai
fainetai na vriskei siga siga to dromo tou gia ton kernel -ginetai
syzhthsh ayto ton kairo sth lista twn xrhstwn tou kernel.org gia to
git repository tou klp. Gia osous de gnwrizoun to tux3 einai ena
kainourio fs pou yposxetai polla kai einai h ekseliksh tou tux2 to
opoio eixe kolhmata logw patentwn (aytos pou to eftiakse eixe
ylopoihsei poly prin patentaristoun tis diafores
leitourgies/algorithmous klp pou to apoteloun kai eprepe na apodiksei
oti den einai elefantas, perissotera infos edw ->
http://lkml.indiana.edu/hypermail/linux/kernel/0010.0/0343.html -etsi
gia na thymomaste poso evil einai oi patentes kai posh zhmia kanoun).
Perissotera infos edw -> http://tux3.org. Kapoies apo tis methodous
pou xrhsimopoiountai sto tux3 efarmozontai sto git...

-- 
GPG ID: 0xD21DB2DB
As you read this post global entropy rises. Have Fun ;-)
Nick