{"id":31079,"date":"2019-10-31T21:39:19","date_gmt":"2019-10-31T18:39:19","guid":{"rendered":"https:\/\/prohoster.info\/blog\/tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete\/"},"modified":"2019-10-31T21:39:19","modified_gmt":"2019-10-31T18:39:19","slug":"tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete","status":"publish","type":"post","link":"https:\/\/prohoster.info\/et\/blog\/administrirovanie\/tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete","title":{"rendered":"TCP steganograafia v\u00f5i kuidas varjata andmeedastust internetis","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"TCP
\n
\nPoola teadlased on pakkunud v\u00e4lja uue v\u00f5rgu steganograafia meetodi, mis p\u00f5hineb laialdaselt levinud TCP taseme transportprotokolli omadustel. T\u00f6\u00f6 autorid usuvad, et nende skeemi saab n\u00e4iteks kasutada varjatud s\u00f5numite edastamiseks totalitaarsetes riikides, kus kehtestatakse ranged interneti tsensuuri meetmed. Uurime, milles tegelikult seisneb uuendus ja kui kasulik see t\u00f5eliselt on.<\/p>\n

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

Esiteks tuleb m\u00e4\u00e4ratleda, mis on steganograafia. Nii et steganograafia on teadus varjatud s\u00f5numite edastamisest. See t\u00e4hendab, et selle meetodite kasutamisel p\u00fc\u00fcavad osalised varjata s\u00f5numi edastamise fakti<\/b>. Selles seisnebki selle teaduse erinevus kr\u00fcptograafiast, mis p\u00fc\u00fcab teha s\u00f5numi sisu loetamatuks.<\/b>. Tuleb m\u00e4rkida, et professionaalne kr\u00fcptograafide kogukond hindab steganograafiat \u00fcsna p\u00f5lglikult, kuna selle ideoloogia sarnaneb p\u00f5him\u00f5ttega \u201eTurvalisus l\u00e4bi ebamugavuste\u201c (ma ei tea, kuidas see \u00f5igesti eesti keeles k\u00f5lab, midagi sellist nagu \u201eTurvalisus teadmiste puudumise kaudu\u201c). Seda p\u00f5him\u00f5tet kasutab n\u00e4iteks ettev\u00f5te Skype Inc. \u2014 nende populaarse telefonirakenduse l\u00e4htekood on suletud ja keegi ei tea t\u00e4pselt, kuidas andmete kr\u00fcptimine toimub. Muide, hiljuti kaebas selle \u00fcle NSA, nagu r\u00e4\u00e4kis tuntud spetsialist Bruce Schneier kirjutas<\/a><\/noindex> oma blogis. <\/p>\n

Tagasi steganograafia juurde, vastame k\u00fcsimusele, miks see \u00fcldse vajalik on, kui on olemas kr\u00fcptograafia. T\u00f5epoolest, s\u00f5numit saab ju kr\u00fcpteerida m\u00f5ne kaasaegse algoritmiga ning piisava pikkusega v\u00f5tmega ei saa keegi seda lugeda, v\u00e4lja arvatud juhul, kui te ei taha. Siiski, m\u00f5nikord on kasulikum varjata isegi asjaolu, et s\u00f5num on salaja edastatud. N\u00e4iteks kui vastavad asutused on teie kr\u00fcpteeritud s\u00f5numi haaranud ja ei suuda seda de\u0161ifreerida, kuid tahavad seda v\u00e4ga, siis l\u00f5puks on olemas ka mitte-arvutistikku kuuluvad meetodid survetegemiseks ja teabe hankimiseks. See k\u00f5lab d\u00fcstoopiliselt, kuid n\u00f5ustuge, et see on p\u00f5him\u00f5tteliselt v\u00f5imalik. Seet\u00f5ttu oleks parem, kui need, kellele ei tohi teada anda, ei teaks \u00fcldse, et edastamine toimus. Poola teadlased on just sellise meetodi v\u00e4lja pakkunud. Ja nad soovitavad seda teha protokolli abil, mida iga interneti kasutaja kasutab tuhat korda p\u00e4evas.<\/p>\n

Siin oleme j\u00f5udnud Transmission Control Protocoli (TCP) juurde. K\u00f5ik selle detailide arutlemine oleks m\u00f5ttetu \u2014 see oleks liiga pikk ja igav, ja need, kellel on vaja, juba teavad. \u00dcldiselt v\u00f5ib \u00f6elda, et TCP on transpordikiht protokoll (st toimib \u201eIP kohal\u201c ja \u201erakenduse protokollide all\u201c, n\u00e4iteks HTTP, FTP v\u00f5i SMTP), mis tagab usaldusv\u00e4\u00e4rse andmete edastamise saatjalt saajale. Usaldusv\u00e4\u00e4rne edastamine t\u00e4hendab, et kui m\u00f5ni paket kaob v\u00f5i j\u00f5uab muudatustega, siis TCP hoolitseb selle eest, et see pakett saadetaks uuesti. Oluline on m\u00e4rkida, et muudatuste all m\u00f5istetakse mitte tahtlikku andmete moonutamist, vaid edastamisvigu, mis tekivad f\u00fc\u00fcsilisel tasandil. N\u00e4iteks, samal ajal kui pakett liigub l\u00e4bi vasest juhtmete, v\u00f5ivad paar biti oma v\u00e4\u00e4rtust muuta vastupidiseks v\u00f5i hoopis kaduda m\u00fcra t\u00f5ttu (\u00dcldiselt, Ethernetis arvatakse, et Bit Error Rate on ligikaudu 10-8). Pakettide kaotamine teel on samuti suhteliselt sage n\u00e4htus internetis. See v\u00f5ib juhtuda n\u00e4iteks marsruuterite koormuse t\u00f5ttu, mis viib puhverdamise \u00fclet\u00e4itumiseni ja seel\u00e4bi k\u00f5igi uus saabuvate paketide mahakandmiseni. Tavaliselt kaotatud paketide osakaal on umbes 0,1%, ja kui see v\u00e4\u00e4rtus t\u00f5useb paariprotsendini, lakkab TCP normaalselt toimimast \u2014 kasutajal toimub k\u00f5ik \u00e4\u00e4rmiselt viivitustega.<\/p>\n

Seega n\u00e4eme, et pakettide edastamine (retsirkulatsioon) on TCP-s sageli esinev ja igati vajalik n\u00e4htus. Nii et miks mitte kasutada seda steganograafia vajadustega, arvestades, et TCP-t, nagu \u00fclal mainitud, kasutatakse laialdaselt (erinevate hinnangute kohaselt on TCP osakaal internetis t\u00e4naseks 80-95% ulatuses). Pakutud meetodi p\u00f5him\u00f5te on saata edastatavas s\u00f5numis mitte seda, mis oli algses paketis, vaid need andmed, mida me p\u00fc\u00fcame varjata. Sel juhul ei ole sellise asenduse avastamine sugugi kerge. L\u00f5ppude l\u00f5puks tuleb teada, kuhu vaadata \u2014 samaaegsete TCP-\u00fchenduste hulk, mis teenusepakkuja kaudu l\u00e4bib, on lihtsalt tohutu. Kui teada ligikaudne retsirkulatsiooni tase v\u00f5rgus, saab steganograafilise edastamise mehhanismi kohandada nii, et teie \u00fchendus ei erineks teistest. <\/p>\n

Muidugi ei ole see meetod puudustest vaba. N\u00e4iteks praktikast l\u00e4htudes ei ole selle rakendamine niisama lihtne \u2014 see n\u00f5uab muudatusi operatsioonis\u00fcsteemide v\u00f5rgukihis, kuigi selles ei ole midagi \u00fclem\u00e4\u00e4ra keerulist. Lisaks, kui ressursse on piisavalt, v\u00f5ib ikkagi avastada \"salajasi\" pakette, selleks tuleb anal\u00fc\u00fcsida iga v\u00f5rku minevat paketti. Kuid tavaliselt on see praktiliselt v\u00f5imatu, seega otsitakse tavaliselt silmapaistvaid pakette ja \u00fchendusi, ning pakutud meetod muudab just teie \u00fchenduse t\u00e4helepanematuks. Ka ei takista miski teid salajaste andmete kr\u00fcpteerimast igaks juhuks. Samal ajal v\u00f5ib ise \u00fchendus j\u00e4\u00e4da kr\u00fcpteerimata, et tekitada v\u00e4hem kahtlust.<\/p>\n

T\u00f6\u00f6 autorid (muide, kellele huvitatud, siin on<\/a><\/noindex> n\u00e4itasid) simuleeritud tasandil, et pakutud meetod t\u00f6\u00f6tab nagu oli kavandatud. Loodetavasti tegeleb keegi tulevikus nende idee rakendamisega praktikas. Siis, loodame, v\u00f5ib internetis natuke v\u00e4hem tsensuuri olla.
\n
Allikas: habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

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Artikli autorid arvavad, et nende skeemi saab n\u00e4iteks kasutada peidetud s\u00f5numite edastamiseks totalitaarsetes riikides, kus kehtivad ranged interneti tsensuuri meetmed. Vaatame, milles seisneb see uuendus ja kui kasulik see t\u00f5eliselt on. Esiteks peame kindlaks tegema","canonical_url":"https:\/\/prohoster.info\/et\/blog\/administrirovanie\/tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"et_EE","og:site_name":"ProHoster | \u041a\u0443\u043f\u0438\u0442\u044c \u043d\u0430\u0434\u0435\u0436\u043d\u044b\u0439 \u0445\u043e\u0441\u0442\u0438\u043d\u0433 \u0434\u043b\u044f \u0441\u0430\u0439\u0442\u043e\u0432 \u0441 \u0437\u0430\u0449\u0438\u0442\u043e\u0439 \u043e\u0442 DDoS, VPS VDS \u0441\u0435\u0440\u0432\u0435\u0440\u044b","og:type":"article","og:title":"\ud83e\udd47TCP \u0441\u0442\u0435\u0433\u0430\u043d\u043e\u0433\u0440\u0430\u0444\u0438\u044f \u0438\u043b\u0438 \u043a\u0430\u043a \u0441\u043a\u0440\u044b\u0442\u044c \u043f\u0435\u0440\u0435\u0434\u0430\u0447\u0443 \u0434\u0430\u043d\u043d\u044b\u0445 \u0432 \u0438\u043d\u0442\u0435\u0440\u043d\u0435\u0442\u0435 | ProHoster","og:description":"\u041f\u043e\u043b\u044c\u0441\u043a\u0438\u0435 \u0438\u0441\u0441\u043b\u0435\u0434\u043e\u0432\u0430\u0442\u0435\u043b\u0438 \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0438\u043b\u0438 \u043d\u043e\u0432\u044b\u0439 \u0441\u043f\u043e\u0441\u043e\u0431 \u0441\u0435\u0442\u0435\u0432\u043e\u0439 \u0441\u0442\u0435\u0433\u0430\u043d\u043e\u0433\u0440\u0430\u0444\u0438\u0438 \u043e\u0441\u043d\u043e\u0432\u0430\u043d\u043d\u044b\u0439 \u043d\u0430 \u043e\u0441\u043e\u0431\u0435\u043d\u043d\u043e\u0441\u0442\u044f\u0445 \u0440\u0430\u0431\u043e\u0442\u044b \u0448\u0438\u0440\u043e\u043a\u043e \u0440\u0430\u0441\u043f\u0440\u043e\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u043d\u043e\u0433\u043e \u043f\u0440\u043e\u0442\u043e\u043a\u043e\u043b\u0430 \u0442\u0440\u0430\u043d\u0441\u043f\u043e\u0440\u0442\u043d\u043e\u0433\u043e \u0443\u0440\u043e\u0432\u043d\u044f TCP. \u0410\u0432\u0442\u043e\u0440\u044b \u0440\u0430\u0431\u043e\u0442\u044b 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