{"id":55176,"date":"2020-01-14T00:00:00","date_gmt":"2020-01-13T21:00:00","guid":{"rendered":"https:\/\/prohoster.info\/blog\/blog_prohoster\/vsyo-chto-vy-hoteli-znat-o-mas-adrese"},"modified":"2020-02-18T14:03:16","modified_gmt":"2020-02-18T11:03:16","slug":"vsyo-chto-vy-hoteli-znat-o-mas-adrese","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/administrirovanie\/vsyo-chto-vy-hoteli-znat-o-mas-adrese","title":{"rendered":"Tot ce a\u021bi vrut s\u0103 \u0219ti\u021bi despre adresa MAC","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"TotEste bine cunoscut c\u0103 aceste \u0219ase bi\u021bi, de obicei afi\u0219a\u021bi \u00een format hexazecimal, sunt aloca\u021bi pl\u0103cii de re\u021bea la fabricare \u0219i, la prima vedere, par aleatorii. Unii \u0219tiu c\u0103 primii trei bi\u021bi ai adresei sunt identificatorul produc\u0103torului, iar ceilal\u021bi trei sunt aloca\u021bi de acesta. De asemenea, se \u0219tie c\u0103 \u00ee\u021bi po\u021bi atribui o adres\u0103<\/em> adres. Mul\u021bi au auzit \u0219i despre \u201eadresele aleatorii\u201d \u00een Wi-Fi.<\/p>\n

<\/p>\n

S\u0103 \u00een\u021belegem ce \u00eenseamn\u0103. <\/p>\n

<\/p>\n

Adresa MAC (media access control address) este un identificator unic, alocat adaptorului de re\u021bea, folosit \u00een re\u021belele standardelor IEEE 802, \u00een principal Ethernet, Wi-Fi \u0219i Bluetooth. Acesta se nume\u0219te oficial \u201eidentificator de tip EUI-48\u201d. Din nume este evident c\u0103 adresa are o lungime de 48 de bi\u021bi, adic\u0103 6 octe\u021bi. Nu exist\u0103 un standard universal pentru scrierea adresei (spre deosebire de adresa IPv4, unde octe\u021bii sunt \u00eentotdeauna separa\u021bi prin puncte). De obicei este scris\u0103 ca \u0219ase numere hexazecimale, separate prin dou\u0103 puncte: 00:AB:CD:EF:11:22, de\u0219i unii produc\u0103tori de echipamente prefer\u0103 formatul 00-AB-CD-EF-11-22 \u0219i chiar 00ab.cdef.1122.<\/p>\n

<\/a><\/noindex><\/p>\n

Istoric, adresele erau scrise \u00een ROM-ul chipsetului pl\u0103cii de re\u021bea f\u0103r\u0103 posibilitatea de a fi modificate f\u0103r\u0103 un programator de flash, dar \u00een prezent, adresa poate fi modificat\u0103 programatic, din sistemul de operare. Po\u021bi seta manual adresa MAC pe placa de re\u021bea \u00een Linux \u0219i MacOS (\u00eentotdeauna), Windows (aproape \u00eentotdeauna, dac\u0103 driverul permite), Android (numai rootat); cu iOS (f\u0103r\u0103 root) o astfel de metod\u0103 nu este posibil\u0103.<\/p>\n

<\/p>\n

Structura adresei<\/h3>\n

<\/p>\n

Adresa const\u0103 dintr-o parte a identificatorului produc\u0103torului, OUI, \u0219i un identificator atribuit de produc\u0103tor. Scopul identificatorilor OUI (Organizationally Unique Identifier) implicat\u0103<\/a><\/noindex> este organiza\u021bia IEEE. De fapt, lungimea sa poate fi nu doar 3 octe\u021bi (24 de bi\u021bi), ci 28 sau 36 de bi\u021bi, din care se formeaz\u0103 blocurile (MAC Address Block, MA) de tipuri Large (MA-L), Medium (MA-M) \u0219i Small (MA-S). Dimensiunea blocului alocat, \u00een acest caz, va fi de 24, 20, 12 bi\u021bi sau 16 milioane, 1 milion, 4 mii de adrese. \u00cen prezent, sunt distribuite aproximativ 38 de mii de blocuri, care pot fi vizualizate cu numeroase instrumente online, de exemplu la IEEE<\/a><\/noindex> sau Wireshark<\/a><\/noindex>.<\/p>\n

<\/p>\n

Cui apar\u021bin adresele<\/h3>\n

<\/p>\n

O analiz\u0103 simpl\u0103 a bazei de date publice de extragere a<\/a><\/noindex> IEEE ofer\u0103 destul de multe informa\u021bii. De exemplu, unele organiza\u021bii au revendicat mult blocuri OUI. Iat\u0103 eroii no\u0219tri:<\/p>\n

<\/p>\n

vendor
\nNum\u0103rul de blocuri\/\u00eenregistr\u0103ri
\nNum\u0103rul de adrese, milioane.<\/p>\n

Cisco Systems Inc
\n888
\n14208<\/p>\n

Apple
\n772
\n12352<\/p>\n

Samsung
\n636
\n10144<\/p>\n

Huawei Technologies Co.Ltd
\n606
\n9696<\/p>\n

Intel Corporation
\n375
\n5776<\/p>\n

ARRIS Group Inc.
\n319
\n5104<\/p>\n

Nokia Corporation
\n241
\n3856<\/p>\n

Privat
\n232
\n2704<\/p>\n

Texas Instruments
\n212
\n3392<\/p>\n

zte corporation
\n198
\n3168<\/p>\n

Autoritatea de \u00cenregistrare IEEE
\n194
\n3072<\/p>\n

Hewlett Packard
\n149
\n2384<\/p>\n

Hon Hai Precision
\n136
\n2176<\/p>\n

TP-LINK
\n134
\n2144<\/p>\n

Dell Inc.
\n123
\n1968<\/p>\n

Juniper Networks
\n110
\n1760<\/p>\n

Sagemcom Broadband SAS
\n97
\n1552<\/p>\n

Fiberhome Telecommunication Technologies Co. LTD
\n97
\n1552<\/p>\n

Xiaomi Communications Co Ltd
\n88
\n1408<\/p>\n

Guangdong Oppo Mobile Telecommunications Corp.Ltd
\n82
\n1312<\/p>\n

<\/p>\n

La Google sunt doar 40, \u0219i nu este de mirare: ei nu produc at\u00e2t de multe dispozitive de re\u021bea.<\/p>\n

<\/p>\n

Blocurile MAC nu sunt oferite gratuit, ci pot fi achizi\u021bionate pentru sume rezonabile (f\u0103r\u0103 tax\u0103 de abonament) de $3000, $1800 sau $755, respectiv. Interesant este c\u0103, pentru o tax\u0103 suplimentar\u0103 (pe an), poate fi achizi\u021bionat un 'scut' pentru informa\u021biile publice despre blocul dedicat. \u00cen prezent, a\u0219a cum se vede, sunt 232 de astfel de blocuri.<\/p>\n

<\/p>\n

C\u00e2nd se vor termina adresele MAC<\/h3>\n

<\/p>\n

To\u021bi suntem destul de s\u0103tui de pove\u0219tile ne\u00eentrerupte timp de 10 ani despre faptul c\u0103 'adresele IPv4 se vor termina cur\u00e2nd'. Da, ob\u021binerea unor noi blocuri IPv4 nu este u\u0219oar\u0103. Este deja cunoscut c\u0103 adresele IP sunt distribuite extrem de inegal<\/a><\/noindex>; exist\u0103 blocuri gigantice \u0219i slab folosite, apar\u021bin\u00e2nd corpora\u021biilor mari \u0219i institu\u021biilor guvernamentale din Statele Unite, f\u0103r\u0103 prea multe speran\u021be de redistribuire \u00een favoarea celor care au nevoie. R\u0103sp\u00e2ndirea NAT, CG-NAT \u0219i IPv6 a f\u0103cut ca problema lipsei adreselor publice s\u0103 nu mai fie at\u00e2t de acut\u0103.<\/p>\n

<\/p>\n

Adresa MAC are 48 de bi\u021bi, din care se pot considera 'utili' 46 (de ce? cite\u0219te mai departe), ceea ce ofer\u0103 246 sau 1014 adrese, adic\u0103 de 214 ori mai mult dec\u00e2t spa\u021biul de adrese IPv4.
\n\u00cen prezent, sunt distribuite aproximativ jum\u0103tate de trilion de adrese, sau doar 0,73% din \u00eentregul volum. P\u00e2n\u0103 la epuizarea adreselor MAC mai este foarte, foarte mult.<\/p>\n

<\/p>\n

Randomizarea bi\u021bilor<\/h3>\n

<\/p>\n

Se poate presupune c\u0103 OUI sunt distribuite aleatoriu, iar furnizorul apoi atribuie de asemenea aleatoriu adrese dispozitivelor de re\u021bea individuale. Este adev\u0103rat? S\u0103 ne uit\u0103m la distribu\u021bia bi\u021bilor \u00een bazele de date de adrese MAC 802.11, adunate de sistemele de autorizare care func\u021bioneaz\u0103 \u00een re\u021belele f\u0103r\u0103 fir. WNAM<\/a><\/noindex>. Adresele apar\u021bin dispozitivelor reale care s-au conectat la Wi-Fi de-a lungul c\u00e2\u021biva ani \u00een trei \u021b\u0103ri. \u00cen plus, exist\u0103 o mic\u0103 baz\u0103 de date pentru dispozitive 802.3 din re\u021belele locale cu fir.<\/p>\n

<\/p>\n

Vom \u00eemp\u0103r\u021bi fiecare adres\u0103 MAC (\u0219ase octe\u021bi) din fiecare e\u0219antion pe bi\u021bi, pe octe\u021bi, \u0219i vom observa frecven\u021ba apari\u021biei bi\u021bilor '1' \u00een fiecare din cele 48 de pozi\u021bii. Dac\u0103 bitul este setat complet aleatoriu, probabilitatea de a ob\u021bine '1' ar trebui s\u0103 fie de 50%.<\/p>\n

<\/p>\n

E\u0219antion Wi-Fi nr. 1 (Rusia)
\nE\u0219antion Wi-Fi nr. 2 (Belarus)
\nExtragerea Wi-Fi nr. 3 (Uzbekistan)
\nExtragerea LAN (Rusia)<\/p>\n

Num\u0103r de \u00eenregistr\u0103ri \u00een baz\u0103
\n5929000
\n1274000
\n366000
\n1000<\/p>\n

Num\u0103rul bitului:
\n% bit \u201e1\u201d
\n% bit \u201e1\u201d
\n% bit \u201e1\u201d
\n% bit \u201e1\u201d<\/p>\n

1
\n48.6%
\n49.2%
\n50.7%
\n28.7%<\/p>\n

2
\n44.8%
\n49.1%
\n47.7%
\n30.7%<\/p>\n

3
\n46.7%
\n48.3%
\n46.8%
\n35.8%<\/p>\n

4
\n48.0%
\n48.6%
\n49.8%
\n37.1%<\/p>\n

5
\n45.7%
\n46.9%
\n47.0%
\n32.3%<\/p>\n

6
\n46.6%
\n46.7%
\n47.8%
\n27.1%<\/p>\n

7
\n0.3%<\/strong>
\n0.3%<\/strong>
\n0.2%<\/strong>
\n0.7%<\/strong><\/p>\n

8
\n0.0%<\/strong>
\n0.0%<\/strong>
\n0.0%<\/strong>
\n0.0%<\/strong><\/p>\n

9
\n48.1%
\n50.6%
\n49.4%
\n38.1%<\/p>\n

10
\n49.1%
\n50.2%
\n47.4%
\n42.7%<\/p>\n

11
\n50.8%
\n50.0%
\n50.6%
\n42.9%<\/p>\n

12
\n49.0%
\n48.4%
\n48.2%
\n53.7%<\/p>\n

13
\n47.6%
\n47.0%
\n46.3%
\n48.5%<\/p>\n

14
\n47.5%
\n47.4%
\n51.7%
\n46.8%<\/p>\n

15
\n48.3%
\n47.5%
\n48.7%
\n46.1%<\/p>\n

16
\n50.6%
\n50.4%
\n51.2%
\n45.3%<\/p>\n

17
\n49.4%
\n50.4%
\n54.3%
\n38.2%<\/p>\n

18
\n49.8%
\n50.5%
\n51.5%
\n51.9%<\/p>\n

19
\n51.6%
\n53.3%
\n53.9%
\n42.6%<\/p>\n

20
\n46.6%
\n46.1%
\n45.5%
\n48.4%<\/p>\n

21
\n51.7%
\n52.9%
\n47.7%
\n48.9%<\/p>\n

22
\n49.2%
\n49.6%
\n41.6%
\n49.8%<\/p>\n

23
\n51.2%
\n50.9%
\n47.0%
\n41.9%<\/p>\n

24
\n49.5%
\n50.2%
\n50.1%
\n47.5%<\/p>\n

25
\n47.1%
\n47.3%
\n47.7%
\n44.2%<\/p>\n

26
\n48.6%
\n48.6%
\n49.2%
\n43.9%<\/p>\n

27
\n49.8%
\n49.0%
\n49.7%
\n48.9%<\/p>\n

28
\n49.3%
\n49.3%
\n49.7%
\n55.1%<\/p>\n

29
\n49.5%
\n49.4%
\n49.8%
\n49.8%<\/p>\n

30
\n49.8%
\n49.8%
\n49.7%
\n52.1%<\/p>\n

31
\n49.5%
\n49.7%
\n49.6%
\n46.6%<\/p>\n

32
\n49.4%
\n49.7%
\n49.5%
\n47.5%<\/p>\n

33
\n49.4%
\n49.8%
\n49.7%
\n48.3%<\/p>\n

34
\n49.7%
\n50.0%
\n49.6%
\n44.9%<\/p>\n

35
\n49.9%
\n50.0%
\n50.0%
\n50.6%<\/p>\n

36
\n49.9%
\n49.9%
\n49.8%
\n49.1%<\/p>\n

37
\n49.8%
\n50.0%
\n49.9%
\n51.4%<\/p>\n

38
\n50.0%
\n50.0%
\n49.8%
\n51.8%<\/p>\n

39
\n49.9%
\n50.0%
\n49.9%
\n55.7%<\/p>\n

40
\n50.0%
\n50.0%
\n50.0%
\n49.5%<\/p>\n

41
\n49.9%
\n50.0%
\n49.9%
\n52.2%<\/p>\n

42
\n50.0%
\n50.0%
\n50.0%
\n53.9%<\/p>\n

43
\n50.1%
\n50.0%
\n50.3%
\n56.1%<\/p>\n

44
\n50.1%
\n50.0%
\n50.1%
\n45.8%<\/p>\n

45
\n50.0%
\n50.0%
\n50.1%
\n50.1%<\/p>\n

46
\n50.0%
\n50.0%
\n50.1%
\n49.5%<\/p>\n

47
\n49.2%
\n49.4%
\n49.7%
\n45.2%<\/p>\n

48
\n49.9%
\n50.1%
\n50.7%
\n54.6%<\/p>\n

<\/p>\n

De unde provine aceast\u0103 nedreptate \u00een bitii 7 \u0219i 8? Acolo sunt aproape \u00eentotdeauna zerouri.<\/p>\n

<\/p>\n

\u00centr-adev\u0103r, standardul define\u0219te ace\u0219ti bi\u021bi ca fiind speciali (Wikipedia<\/a><\/noindex>):
\n\"Tot<\/p>\n

<\/p>\n

Bitul opt (de la \u00eenceput) al primului octet al adresei MAC se nume\u0219te bit Unicast\/Multicast \u0219i determin\u0103 tipul de cadru (frame) transmis cu aceast\u0103 adres\u0103, normal (0) sau difuzare (1) (multicast sau broadcast). Pentru o interac\u021biune unicast normal\u0103 a adaptorului de re\u021bea, acest bit este setat la \u201e0\u201d \u00een toate pachetele trimise.<\/p>\n

<\/p>\n

Bitul \u0219apte (de la \u00eenceput) al primului octet al adresei MAC se nume\u0219te bit U\/L (Universal\/Local) \u0219i determin\u0103 dac\u0103 adresa este global unic\u0103 (0) sau local unic\u0103 (1). \u00cen mod implicit, toate adresele \u201eprogramate de fabricant\u201d sunt global unice, de aceea, marea majoritate a adreselor MAC colectate con\u021bin bitul \u0219apte setat la \u201e0\u201d. \u00cen tabelul identificatorilor atribui\u021bi OUI, doar aproximativ 130 de \u00eenregistr\u0103ri au bitul U\/L \u201e1\u201d, iar aparent acestea sunt blocuri de adrese MAC pentru nevoi speciale.<\/p>\n

<\/p>\n

Din bitul \u0219ase p\u00e2n\u0103 la primul bit al primului octet, bi\u021bii din al doilea \u0219i al treilea octet din identificatorii OUI, \u0219i cu at\u00e2t mai mult bi\u021bii din octe\u021bii 4-6 ai adresei, atribui\u021bi de fabricant, sunt distribui\u021bi mai mult sau mai pu\u021bin uniform. <\/p>\n

<\/p>\n

Astfel, \u00een adresa MAC real\u0103 a adaptorului de re\u021bea, bi\u021bii sunt de fapt echivalen\u021bi \u0219i nu au sens tehnologic, cu excep\u021bia celor dou\u0103 bi\u021bi de servicii din octetul de mo\u0219tenire.<\/p>\n

<\/p>\n

R\u0103sp\u00e2ndire<\/h3>\n

<\/p>\n

Este interesant de \u0219tiut care produc\u0103tori de echipamente wireless sunt cei mai populari? S\u0103 unific\u0103m c\u0103utarea \u00een baza OUI cu datele extragerii nr. 1.<\/p>\n

<\/p>\n

vendor
\nCota de pia\u021b\u0103 a dispozitivelor, %<\/p>\n

Apple
\n26,09<\/p>\n

Samsung
\n19,79<\/p>\n

Huawei Technologies Co. Ltd
\n7,80<\/p>\n

Xiaomi Communications Co Ltd
\n6,83<\/p>\n

Sony Mobile Communications Inc
\n3,29<\/p>\n

LG Electronics (Mobile Communications)
\n2,76<\/p>\n

ASUSTek COMPUTER INC.
\n2,58<\/p>\n

TCT mobile ltd
\n2,13<\/p>\n

zte corporation
\n2,00<\/p>\n

neidentificat \u00een baza IEEE
\n1,92<\/p>\n

Lenovo Mobile Communication Technology Ltd.
\n1,71<\/p>\n

HTC Corporation
\n1,68<\/p>\n

Murata Manufactuaring
\n1,31<\/p>\n

InPro Comm
\n1,26<\/p>\n

Microsoft Corporation
\n1,11<\/p>\n

Shenzhen TINNO Mobile Technology Corp.
\n1,02<\/p>\n

Motorola (Wuhan) Mobility Technologies Communication Co. Ltd.
\n0,93<\/p>\n

Nokia Corporation
\n0,88<\/p>\n

Shanghai Wind Technologies Co. Ltd
\n0,74<\/p>\n

Lenovo Mobile Communication (Wuhan) Company Limited
\n0,71<\/p>\n

<\/p>\n

Practic\u0103 arat\u0103 c\u0103 cu c\u00e2t mai \u00eenst\u0103rit este contagenta abona\u021bilor re\u021belei wireless din acest loc, cu at\u00e2t mai mare este cota de pia\u021b\u0103 a dispozitivelor Apple.<\/p>\n

<\/p>\n

Unicitate<\/h3>\n

<\/p>\n

Sunt adreselor MAC unice? Teoretic, da, deoarece fiecare dintre produc\u0103torii de dispozitive (proprietarii blocurilor MA) trebuie s\u0103 asigure o adres\u0103 unic\u0103 pentru fiecare dintre adaptoarele de re\u021bea pe care le produc. Cu toate acestea, unii produc\u0103tori de cipuri, \u0219i anume:<\/p>\n

<\/p>\n