{"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\/sk\/blog\/administrirovanie\/vsyo-chto-vy-hoteli-znat-o-mas-adrese","title":{"rendered":"V\u0161etko, \u010do ste chceli vedie\u0165 o MAC adrese","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"V\u0161etko,Je zn\u00e1me, \u017ee t\u00fdchto \u0161es\u0165 bajtov, zvy\u010dajne zobrazen\u00fdch v hexadecim\u00e1lnom form\u00e1te, je pridelen\u00fdch sie\u0165ovej karte v tov\u00e1rni a na prv\u00fd poh\u013ead sa zdaj\u00fa by\u0165 n\u00e1hodn\u00e9. Niektor\u00ed vedia, \u017ee prv\u00e9 tri bajty adresy s\u00fa identifik\u00e1torom v\u00fdrobcu, zatia\u013e \u010do zvy\u0161n\u00e9 tri bajty s\u00fa im pridelen\u00e9. Je tie\u017e zn\u00e1me, \u017ee si m\u00f4\u017eete priradi\u0165 n\u00e1hodn\u00fa<\/em> adresa. Mnoh\u00ed po\u010duli aj o «n\u00e1hodn\u00fdch adres\u00e1ch» vo Wi-Fi.<\/p>\n

<\/p>\n

Po\u010fme sa pozrie\u0165, \u010do to vlastne je. <\/p>\n

<\/p>\n

MAC adresa (media access control address) \u2013 jedine\u010dn\u00fd identifik\u00e1tor priraden\u00fd sie\u0165ov\u00e9mu adapt\u00e9ru, ktor\u00fd sa pou\u017e\u00edva v sie\u0165ach \u0161tandardov IEEE 802, najm\u00e4 Ethernet, Wi-Fi a Bluetooth. Ofici\u00e1lne sa naz\u00fdva \u201eidentifik\u00e1tor typu EUI-48\u201c. Z n\u00e1zvu je jasn\u00e9, \u017ee adresa m\u00e1 d\u013a\u017eku 48 bitov, t.j. 6 bajtov. Neexistuje \u017eiadny v\u0161eobecne prijat\u00fd \u0161tandard na z\u00e1pis adresy (na rozdiel od adresy IPv4, kde s\u00fa oktety v\u017edy oddelen\u00e9 bodkami). Zvy\u010dajne je zapisovan\u00e1 ako \u0161es\u0165 hexadecim\u00e1lnych \u010d\u00edslic oddelen\u00fdch dvojbodkami: 00:AB:CD:EF:11:22, hoci niektor\u00ed v\u00fdrobcovia hardv\u00e9ru uprednost\u0148uj\u00fa z\u00e1pis vo forme 00-AB-CD-EF-11-22 a dokonca aj 00ab.cdef.1122.<\/p>\n

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

Historicky boli adresy zap\u00edsan\u00e9 do ROM \u010dipsetu sie\u0165ovej karty bez mo\u017enosti ich modifik\u00e1cie bez flash program\u00e1tora, ale v s\u00fa\u010dasnosti m\u00f4\u017ee by\u0165 adresa zmenen\u00e1 softv\u00e9rovo z opera\u010dn\u00e9ho syst\u00e9mu. Manu\u00e1lne nastavi\u0165 MAC adresu sie\u0165ovej karte je mo\u017en\u00e9 v Linuxe a MacOS (v\u017edy), Windows (takmer v\u017edy, ak to dovo\u013euje ovl\u00e1da\u010d), Android (iba rootovan\u00e1); s iOS (bez root) nie je tak\u00fdto trik mo\u017en\u00fd.<\/p>\n

<\/p>\n

\u0160trukt\u00fara adresy<\/h3>\n

<\/p>\n

Adresa sa sklad\u00e1 z \u010dasti identifik\u00e1tora v\u00fdrobcu, OUI, a identifik\u00e1tora, ktor\u00fd pridelil v\u00fdrobca. Pridelen\u00edm identifik\u00e1torov OUI (Organizationally Unique Identifier) sa zaober\u00e1<\/a><\/noindex> organiz\u00e1ciou IEEE. V skuto\u010dnosti jeho d\u013a\u017eka nemus\u00ed by\u0165 len 3 bajty (24 bitov), ale m\u00f4\u017ee by\u0165 aj 28 alebo 36 bitov, z ktor\u00fdch sa vytv\u00e1raj\u00fa bloky (MAC Address Block, MA) adries typov Large (MA-L), Medium (MA-M) a Small (MA-S) v z\u00e1vislosti od. Ve\u013ekos\u0165 vydan\u00e9ho bloku v takom pr\u00edpade bude 24, 20, 12 bitov alebo 16 mili\u00f3nov, 1 mili\u00f3n, 4 tis\u00edce adries. V s\u00fa\u010dasnosti je prerozdelen\u00fdch pribli\u017ene 38 tis\u00edc blokov, ktor\u00e9 je mo\u017en\u00e9 zobrazi\u0165 pomocou mnoh\u00fdch online n\u00e1strojov, napr\u00edklad na IEEE<\/a><\/noindex> alebo Wireshark<\/a><\/noindex>.<\/p>\n

<\/p>\n

Komu patria adresy<\/h3>\n

<\/p>\n

Jednoduch\u00e1 anal\u00fdza verejne dostupnej datab\u00e1zy v\u00fdstupu<\/a><\/noindex> IEEE poskytuje pomerne ve\u013ea inform\u00e1ci\u00ed. Napr\u00edklad niektor\u00e9 organiz\u00e1cie si prideli\u0165 ve\u013ea blokov OUI. Tu s\u00fa na\u0161i hrdinovia:<\/p>\n

<\/p>\n

Dod\u00e1vate\u013e
\nPo\u010det blokov\/z\u00e1znamov
\nPo\u010det adries, mili\u00f3ny.<\/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

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

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

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

IEEE Registration Authority
\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

V Google ich je len 40 a nie je to prekvapuj\u00face: sami nevyr\u00e1baj\u00fa to\u013eko sie\u0165ov\u00fdch zariaden\u00ed.<\/p>\n

<\/p>\n

Bloky MAC nie s\u00fa poskytovan\u00e9 zadarmo, m\u00f4\u017eu sa zak\u00fapi\u0165 za rozumn\u00e9 ceny (bez mesa\u010dn\u00fdch poplatkov) za 3000 dol\u00e1rov, 1800 dol\u00e1rov alebo 755 dol\u00e1rov. Zauj\u00edmav\u00e9 je, \u017ee za dodato\u010dn\u00e9 ro\u010dn\u00e9 n\u00e1klady si m\u00f4\u017eete zak\u00fapi\u0165 \u201eskrytie\u201c verejn\u00fdch inform\u00e1ci\u00ed o pridelenom bloku. Tak\u00fdch je teraz, ako je vidno vy\u0161\u0161ie, 232.<\/p>\n

<\/p>\n

Kedy sa MAC adresy vy\u010derpaj\u00fa<\/h3>\n

<\/p>\n

V\u0161etci sme u\u017e poriadne unaven\u00ed z neust\u00e1lych rozpr\u00e1van\u00ed posledn\u00fdch 10 rokov o tom, \u017ee \u201eIPv4 adresy sa \u00fadajne \u010doskoro vy\u010derpaj\u00fa\u201c. \u00c1no, nov\u00e9 bloky IPv4 sa u\u017e \u0165a\u017eko z\u00edskavaj\u00fa. Z\u00e1rove\u0148 je zn\u00e1me, \u017ee IP adresy s\u00fa rozdelen\u00e9 ve\u013emi nerovnomerne<\/a><\/noindex>; existuj\u00fa obrovsk\u00e9 a m\u00e1lo vyu\u017e\u00edvan\u00e9 bloky patriace ve\u013ek\u00fdm korpor\u00e1ci\u00e1m a \u0161t\u00e1tnym in\u0161tit\u00faci\u00e1m USA, av\u0161ak bez osobnej n\u00e1deje na ich prelo\u017eenie v prospech t\u00fdch, ktor\u00ed ich potrebuj\u00fa. Roz\u0161\u00edrenie NAT, CG-NAT a IPv6 zn\u00ed\u017eilo tlak na nedostatok verejn\u00fdch adries.<\/p>\n

<\/p>\n

V MAC adrese je 48 bitov, z ktor\u00fdch sa za \u201eu\u017eito\u010dn\u00e9\u201c daj\u00fa pova\u017eova\u0165 46 (pre\u010do? \u010d\u00edtaj \u010falej), \u010do d\u00e1va 2^46 alebo 1014 adries, \u010do je 2^14-kr\u00e1t viac ako IPv4 adresn\u00fd priestor.
\nV s\u00fa\u010dasnosti je pridelen\u00fdch pribli\u017ene pol trili\u00f3na adries, alebo len 0.73% z celkov\u00e9ho objemu. Do vy\u010derpania MAC adries je e\u0161te ve\u013emi, ve\u013emi \u010faleko.<\/p>\n

<\/p>\n

N\u00e1hodnos\u0165 bitu<\/h3>\n

<\/p>\n

M\u00f4\u017eeme predpoklada\u0165, \u017ee OUI s\u00fa distribuovan\u00e9 n\u00e1hodne a dod\u00e1vate\u013e n\u00e1sledne tie\u017e n\u00e1hodne pride\u013euje adresy individu\u00e1lnym sie\u0165ov\u00fdm zariadeniam. Je to naozaj tak? Pozrime sa na rozdelenie bitov v existuj\u00facich datab\u00e1zach MAC adries zariaden\u00ed 802.11, zhroma\u017eden\u00fdch funguj\u00facimi syst\u00e9mami autoriz\u00e1cie v bezdr\u00f4tov\u00fdch sie\u0165ach WNAM<\/a><\/noindex>. Adresy patria re\u00e1lnym zariadeniam, ktor\u00e9 sa pripojili k Wi-Fi po\u010das nieko\u013ek\u00fdch rokov v troch krajin\u00e1ch. K tomu sa prid\u00e1va aj mal\u00e1 datab\u00e1za zariaden\u00ed 802.3 v k\u00e1blov\u00fdch LAN.<\/p>\n

<\/p>\n

Rozdel\u00edme ka\u017ed\u00fa MAC adresu (\u0161es\u0165 bajtov) z ka\u017edej zo vzoriek na bity po bajtoch a pozrieme sa na frekvenciu v\u00fdskytu bitu \u201e1\u201c v ka\u017edej z 48 poz\u00edci\u00ed. Ak je bit nastaven\u00fd \u00faplne n\u00e1hodne, pravdepodobnos\u0165 z\u00edskania \u201e1\u201c by mala by\u0165 50%.<\/p>\n

<\/p>\n

Vzorov\u00e1 Wi-Fi \u010d. 1 (RF)
\nVzorov\u00e1 Wi-Fi \u010d. 2 (Bielorusko)
\nVzorov\u00e1 Wi-Fi \u010d. 3 (Uzbekistan)
\nV\u00fdberka LAN (SK)<\/p>\n

Po\u010det z\u00e1znamov v datab\u00e1ze
\n5929000
\n1274000
\n366000
\n1000<\/p>\n

\u010c\u00edslo bitu:
\n% bit «1»
\n% bit «1»
\n% bit «1»
\n% bit «1»<\/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

Odkia\u013e poch\u00e1dza tak\u00e1 nespravodlivos\u0165 v 7. a 8. bitoch? Tam s\u00fa takmer v\u017edy nuly.<\/p>\n

<\/p>\n

Skuto\u010dne, norma ur\u010duje tieto bity ako \u0161peci\u00e1lne (Wikipedia<\/a><\/noindex>):
\n\"V\u0161etko,<\/p>\n

<\/p>\n

\u00d4smy (od za\u010diatku) bit prv\u00e9ho bajtu MAC adresy sa naz\u00fdva Unicast\/Multicast bit a ur\u010duj\u00fa, ak\u00fd typ r\u00e1mca (frame) sa pren\u00e1\u0161a s touto adresou, be\u017en\u00fd (0) alebo \u0161irokop\u00e1smov\u00fd (1) (multicast alebo broadcast). Pre be\u017en\u00fa, unicast interakciu sie\u0165ov\u00e9ho adapt\u00e9ru, je tento bit nastaven\u00fd na \u201e0\u201c vo v\u0161etk\u00fdch paketoch, ktor\u00e9 s\u00fa mu zasielan\u00e9.<\/p>\n

<\/p>\n

Siedmy (od za\u010diatku) bit prv\u00e9ho bajtu MAC adresy sa naz\u00fdva U\/L (Universal\/Local) bit a ur\u010duje, \u010di je adresa glob\u00e1lne jedine\u010dn\u00e1 (0) alebo lok\u00e1lne jedine\u010dn\u00e1 (1). Predvolene, v\u0161etky \u201enaprogramovan\u00e9 v\u00fdrobcom\u201c adresy s\u00fa glob\u00e1lne jedine\u010dn\u00e9, tak\u017ee drviv\u00e1 v\u00e4\u010d\u0161ina zozbieran\u00fdch MAC adries obsahuje siedmy bit nastaven\u00fd na \u201e0\u201c. V tabu\u013eke pridelen\u00fdch identifik\u00e1torov OUI m\u00e1 iba pribli\u017ene 130 z\u00e1znamov U\/L bit \u201e1\u201c, a zrejme s\u00fa to bloky MAC adries pre \u0161peci\u00e1lne potreby.<\/p>\n

<\/p>\n

Od \u0161iesteho po prv\u00fd bit prv\u00e9ho bajtu, bity druh\u00e9ho a tretieho bajtu v OUI identifik\u00e1toroch, a t\u00fdm sk\u00f4r bity v 4-6 bajtoch adresy, ktor\u00e9 pridelil v\u00fdrobca, s\u00fa rozdelen\u00e9 viac-menej rovnomerne. <\/p>\n

<\/p>\n

Tak\u017ee v re\u00e1lnom MAC-adrese sie\u0165ov\u00e9ho adapt\u00e9ru s\u00fa bity v podstate rovnak\u00e9 a nenes\u00fa technologick\u00fd v\u00fdznam, okrem dvoch pomocn\u00fdch bitov najvy\u0161\u0161ieho bajtu.<\/p>\n

<\/p>\n

Roz\u0161\u00edrenie<\/h3>\n

<\/p>\n

Zauj\u00edmav\u00e9, ktor\u00fdch v\u00fdrobcov bezdr\u00f4tov\u00e9ho zariadenia je najviac popul\u00e1rnych? Spojme h\u013eadanie v datab\u00e1ze OUI s \u00fadajmi zo vzorky \u010d. 1.<\/p>\n

<\/p>\n

Dod\u00e1vate\u013e
\nPodiel zariaden\u00ed, %<\/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 (Mobiln\u00e9 komunik\u00e1cie)
\n2,76<\/p>\n

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

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

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

nen\u00e1jden\u00e9 v datab\u00e1ze 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

Praktika ukazuje, \u017ee \u010d\u00edm bohat\u0161\u00ed je kontingent predplatite\u013eov bezdr\u00f4tovej siete na danom mieste, t\u00fdm v\u00e4\u010d\u0161\u00ed podiel zariaden\u00ed Apple.<\/p>\n

<\/p>\n

Jedine\u010dnos\u0165<\/h3>\n

<\/p>\n

S\u00fa MAC adresy jedine\u010dn\u00e9? V te\u00f3rii \u00e1no, preto\u017ee ka\u017ed\u00fd z v\u00fdrobcov zariaden\u00ed (majite\u013e bloku MA) je povinn\u00fd zabezpe\u010di\u0165 jedine\u010dn\u00fa adresu pre ka\u017ed\u00e9ho zo svojich sie\u0165ov\u00fdch adapt\u00e9r. Av\u0161ak niektor\u00ed v\u00fdrobcovia \u010dipov, a to konkr\u00e9tne:<\/p>\n

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