{"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\/cs\/blog\/administrirovanie\/tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete","title":{"rendered":"TCP steganografie nebo jak skr\u00fdt p\u0159enos dat na internetu","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

\"TCP
\n
\nPol\u0161t\u00ed v\u011bdci navrhli nov\u00fd zp\u016fsob s\u00ed\u0165ov\u00e9 steganografie, kter\u00fd je zalo\u017een na zvl\u00e1\u0161tnostech fungov\u00e1n\u00ed \u0161iroce vyu\u017e\u00edvan\u00e9ho transportn\u00edho protokolu TCP. Auto\u0159i tohoto v\u00fdzkumu se domn\u00edvaj\u00ed, \u017ee jejich sch\u00e9ma by mohlo b\u00fdt nap\u0159\u00edklad pou\u017eito k p\u0159enosu skryt\u00fdch zpr\u00e1v v totalitn\u00edch zem\u00edch, kter\u00e9 zav\u00e1d\u011bj\u00ed p\u0159\u00edsnou internetovou cenzuru. Poj\u010fme se pod\u00edvat na to, v \u010dem spo\u010d\u00edv\u00e1 novinka a jak u\u017eite\u010dn\u00e1 skute\u010dn\u011b je.<\/p>\n

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

Nejd\u0159\u00edve je t\u0159eba definovat, co je steganografie. Tak\u017ee, steganografie je v\u011bda o skryt\u00e9m p\u0159enosu zpr\u00e1v. To znamen\u00e1, \u017ee p\u0159i pou\u017eit\u00ed jej\u00edch metod se strany sna\u017e\u00ed skr\u00fdt s\u00e1m fakt p\u0159enosu<\/b>. A v tom tkv\u00ed rozd\u00edl mezi touto v\u011bdou a kryptografi\u00ed, kter\u00e1 se sna\u017e\u00ed u\u010dinit obsah zpr\u00e1vy nep\u0159\u00edstupn\u00fdm pro \u010dten\u00ed<\/b>. Je t\u0159eba poznamenat, \u017ee profesion\u00e1ln\u00ed kryptografick\u00e1 komunita se na steganografii d\u00edv\u00e1 s ur\u010dit\u00fdm pohrd\u00e1n\u00edm, vzhledem k bl\u00edzkosti jej\u00ed ideologie k principu \u201eBezpe\u010dnost skrze neznalost\u201c. Tento princip nap\u0159\u00edklad pou\u017e\u00edv\u00e1 spole\u010dnost Skype Inc. \u2014 zdrojov\u00fd k\u00f3d popul\u00e1rn\u00ed telefonn\u00ed aplikace je uzav\u0159en a nikdo p\u0159esn\u011b nev\u00ed, jak\u00fdm zp\u016fsobem je zaji\u0161t\u011bno \u0161ifrov\u00e1n\u00ed dat. Ned\u00e1vno se o tom mimochodem zmi\u0148ovali v NSA, o \u010dem\u017e zn\u00e1m\u00fd odborn\u00edk Bruce Schneier napsal<\/a><\/noindex> napsal na sv\u00e9m blogu. <\/p>\n

Kdy\u017e se vr\u00e1t\u00edme ke steganografii, odpov\u011bzme na ot\u00e1zku, pro\u010d je v\u016fbec pot\u0159ebn\u00e1, kdy\u017e existuje kryptografie. Opravdu, lze za\u0161ifrovat zpr\u00e1vu pomoc\u00ed n\u011bjak\u00e9ho modern\u00edho algoritmu a s pou\u017eit\u00edm dostate\u010dn\u011b dlouh\u00e9ho kl\u00ed\u010de si nikdo tuto zpr\u00e1vu p\u0159e\u010d\u00edst nem\u016f\u017ee, pokud si to nep\u0159ejete. A p\u0159esto, n\u011bkdy m\u016f\u017ee b\u00fdt u\u017eite\u010dn\u011bj\u0161\u00ed skr\u00fdt samotn\u00fd fakt tajn\u00e9ho p\u0159enosu. Nap\u0159\u00edklad, pokud p\u0159\u00edslu\u0161n\u00e9 org\u00e1ny zachyt\u00ed va\u0161i za\u0161ifrovanou zpr\u00e1vu, nemohou ji de\u0161ifrovat, ale pokud si velmi p\u0159ej\u00ed, existuj\u00ed i jin\u00e9, po\u010d\u00edta\u010dov\u011b nevy\u017eaduj\u00edc\u00ed metody ovliv\u0148ov\u00e1n\u00ed a z\u00edsk\u00e1v\u00e1n\u00ed informac\u00ed. Zn\u00ed to dystopicky, ale, souhlas\u00edte, takov\u00e1 situace je v z\u00e1sad\u011b mo\u017en\u00e1. Proto by bylo lep\u0161\u00ed ud\u011blat to tak, aby ti, kdo nemaj\u00ed \u017e\u00e1dn\u00e9 opr\u00e1vn\u011bn\u00ed, v\u016fbec netu\u0161ili, \u017ee k p\u0159enosu do\u0161lo. Pol\u0161t\u00ed v\u011bdci pr\u00e1v\u011b navrhli takovou metodu. A to navrhuj\u00ed prov\u00e9st pomoc\u00ed protokolu, kter\u00fd ka\u017ed\u00fd u\u017eivatel internetu pou\u017e\u00edv\u00e1 tis\u00edckr\u00e1t denn\u011b.<\/p>\n

Zde jsme se bl\u00edzko p\u0159ibl\u00ed\u017eili k protokolu Transmission Control Protocol (TCP). Vysv\u011btlovat v\u0161echny jeho detaily, samoz\u0159ejm\u011b, ned\u00e1v\u00e1 smysl \u2013 je to dlouh\u00e9, nudn\u00e9 a ti, kdo to pot\u0159ebuj\u00ed, to u\u017e d\u00e1vno znaj\u00ed. Stru\u010dn\u011b \u0159e\u010deno, TCP je protokol transportn\u00ed vrstvy (tj. funguje \u201enad\u201c IP a \u201epod\u201c aplika\u010dn\u00edmi protokoly, jako jsou HTTP, FTP nebo SMTP), kter\u00fd zaji\u0161\u0165uje spolehliv\u00e9 doru\u010den\u00ed dat od odes\u00edlatele k p\u0159\u00edjemci. Spolehliv\u00e9 doru\u010den\u00ed znamen\u00e1, \u017ee pokud se n\u011bjak\u00fd datov\u00fd paket ztrat\u00ed nebo doraz\u00ed s chybami, TCP se postar\u00e1 o jeho op\u011btovn\u00e9 odesl\u00e1n\u00ed. Je t\u0159eba poznamenat, \u017ee \u201ezm\u011bny\u201c v paketu zde odkazuj\u00ed na nezam\u00fd\u0161len\u00e9 zkreslen\u00ed dat, nikoli na \u00famysln\u00e9 chyby, kter\u00e9 vznikaj\u00ed na fyzick\u00e9 \u00farovni p\u0159enosu. Nap\u0159\u00edklad, zat\u00edmco paket putoval po m\u011bd\u011bn\u00fdch dr\u00e1tech, mohly se n\u011bkter\u00e9 bity zm\u011bnit na opa\u010dn\u00e9 hodnoty nebo se \u00fapln\u011b ztratit mezi \u0161umem (mimochodem, pro Ethernet je hodnota Bit Error Rate obvykle p\u0159ij\u00edm\u00e1na jako p\u0159ibli\u017en\u011b 10-8). Ztr\u00e1ta paket\u016f b\u011bhem cesty je tak\u00e9 pom\u011brn\u011b \u010dast\u00fdm jevem na internetu. M\u016f\u017ee k n\u00ed doj\u00edt nap\u0159\u00edklad kv\u016fli p\u0159et\u00ed\u017een\u00ed router\u016f, co\u017e vede k p\u0159ete\u010den\u00ed bufferingu a v d\u016fsledku toho k odm\u00edtnut\u00ed v\u0161ech nov\u011b p\u0159\u00edchoz\u00edch paket\u016f. Obvykle pod\u00edl ztracen\u00fdch paket\u016f \u010din\u00ed kolem 0,1 %, a p\u0159i hodnot\u011b n\u011bkolika procent TCP zcela p\u0159est\u00e1v\u00e1 norm\u00e1ln\u011b fungovat \u2013 u\u017eivateli v\u0161echno \u0161\u00edlen\u011b zamrz\u00e1.<\/p>\n

Tak\u017ee vid\u00edme, \u017ee retransmise paket\u016f je pro TCP \u010dast\u00fdm a v podstat\u011b pot\u0159ebn\u00fdm jevem. Pro\u010d tedy nevyu\u017e\u00edt TCP pro pot\u0159eby steganografie, kdy\u017e u\u017e bylo zm\u00edn\u011bno, \u017ee je \u0161iroce pou\u017e\u00edvan\u00fd (podle r\u016fzn\u00fdch odhad\u016f dnes tvo\u0159\u00ed pod\u00edl TCP na internetu 80-95 %)? Podstata navr\u017een\u00e9 metody spo\u010d\u00edv\u00e1 v tom, \u017ee do odes\u00edlan\u00e9 zpr\u00e1vy se pos\u00edlaj\u00ed nikoli data obsa\u017een\u00e1 v p\u016fvodn\u00edm paketu, ale ta, kter\u00e1 se sna\u017e\u00edme skr\u00fdt. Objevov\u00e1n\u00ed takov\u00e9 n\u00e1hrady v\u0161ak nen\u00ed tak jednoduch\u00e9. Je t\u0159eba v\u011bd\u011bt, kam se d\u00edvat \u2013 po\u010det soub\u011b\u017en\u00fdch TCP p\u0159ipojen\u00ed proch\u00e1zej\u00edc\u00edch poskytovatelem je zcela obrovsk\u00fd. Pokud zn\u00e1te p\u0159ibli\u017enou \u00farove\u0148 retransmise v s\u00edti, m\u016f\u017eete p\u0159izp\u016fsobit mechanismus steganografick\u00e9 retransmise tak, aby va\u0161e p\u0159ipojen\u00ed nijak nevynikalo od ostatn\u00edch. <\/p>\n

Samoz\u0159ejm\u011b, \u017ee tato metoda nen\u00ed bez nedostatk\u016f. Nap\u0159\u00edklad z praktick\u00e9ho hlediska nebude jej\u00ed zaveden\u00ed tak jednoduch\u00e9 \u2014 to si bude vy\u017eadovat zm\u011bny v s\u00ed\u0165ov\u00e9m z\u00e1sobn\u00edku opera\u010dn\u00edch syst\u00e9m\u016f, a\u010dkoli na tom nen\u00ed nic extr\u00e9mn\u011b slo\u017eit\u00e9ho. Krom\u011b toho, pokud m\u00e1te dostatek zdroj\u016f, lze st\u00e1le odhalit \"skryt\u00e9\" pakety; k tomu je nutn\u00e9 proch\u00e1zet a analyzovat ka\u017ed\u00fd paket v s\u00edti. Ale zpravidla je to prakticky nemo\u017en\u00e9, proto se obvykle hledaj\u00ed n\u011bjak\u00e9 v\u00fdjime\u010dn\u00e9 pakety a spojen\u00ed, a navrhovan\u00e1 metoda \u010din\u00ed va\u0161e spojen\u00ed nep\u0159ipom\u00ednaj\u00edc\u00edm nic zvl\u00e1\u0161tn\u00edho. A nikdo v\u00e1m tak\u00e9 nebr\u00e1n\u00ed za\u0161ifrovat skryt\u00e1 data pro v\u0161echny p\u0159\u00edpady. Samotn\u00e9 spojen\u00ed v\u0161ak m\u016f\u017ee z\u016fstat neza\u0161ifrovan\u00e9, aby vzbuzovalo m\u00e9n\u011b podez\u0159en\u00ed.<\/p>\n

Auto\u0159i pr\u00e1ce (mimochodem, pro zaj\u00edmavost, tady je<\/a><\/noindex> to) na \u00farovni simulac\u00ed uk\u00e1zali, \u017ee navrhovan\u00e1 metoda funguje, jak bylo zam\u00fd\u0161leno. Mo\u017en\u00e1, \u017ee v budoucnu se n\u011bkdo ujme realizace jejich my\u0161lenky v praxi. A pak, doufejme, na internetu bude o n\u011bco m\u00e9n\u011b cenzury.
\n
Zdroj: habr.com<\/a><\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\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 \u0441\u0447\u0438\u0442\u0430\u044e\u0442, \u0447\u0442\u043e \u0438\u0445 \u0441\u0445\u0435\u043c\u0430, \u043a \u043f\u0440\u0438\u043c\u0435\u0440\u0443, \u043c\u043e\u0436\u0435\u0442 \u043f\u0440\u0438\u043c\u0435\u043d\u044f\u0442\u044c\u0441\u044f \u0434\u043b\u044f \u043f\u0435\u0440\u0435\u0441\u044b\u043b\u043a\u0438 \u0441\u043a\u0440\u044b\u0442\u044b\u0445 \u0441\u043e\u043e\u0431\u0449\u0435\u043d\u0438\u0439 \u0432 \u0442\u043e\u0442\u0430\u043b\u0438\u0442\u0430\u0440\u043d\u044b\u0445 \u0441\u0442\u0440\u0430\u043d\u0430\u0445 \u0432\u0432\u043e\u0434\u044f\u0449\u0438\u0445 \u0436\u0435\u0441\u0442\u043a\u0443\u044e \u0438\u043d\u0442\u0435\u0440\u043d\u0435\u0442 \u0446\u0435\u043d\u0437\u0443\u0440\u0443. \u041f\u043e\u043f\u0440\u043e\u0431\u0443\u0435\u043c \u0440\u0430\u0437\u043e\u0431\u0440\u0430\u0442\u044c\u0441\u044f \u0432 \u0447\u0435\u043c, \u0441\u043e\u0431\u0441\u0442\u0432\u0435\u043d\u043d\u043e, \u0441\u043e\u0441\u0442\u043e\u0438\u0442 \u043d\u043e\u0432\u043e\u0432\u0432\u0435\u0434\u0435\u043d\u0438\u0435 \u0438 \u043d\u0430\u0441\u043a\u043e\u043b\u044c\u043a\u043e \u043e\u043d\u043e \u0434\u0435\u0439\u0441\u0442\u0432\u0438\u0442\u0435\u043b\u044c\u043d\u043e \u043f\u043e\u043b\u0435\u0437\u043d\u043e. \u0412 \u043f\u0435\u0440\u0432\u0443\u044e \u043e\u0447\u0435\u0440\u0435\u0434\u044c \u043d\u0443\u0436\u043d\u043e \u043e\u043f\u0440\u0435\u0434\u0435\u043b\u0438\u0442\u044c […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[688],"tags":[],"class_list":["post-31079","post","type-post","status-publish","format-standard","hentry","category-administrirovanie"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47TCP steganografie nebo jak skr\u00fdt p\u0159enos dat v internetu | ProHoster","description":"Pol\u0161t\u00ed v\u00fdzkumn\u00edci.","canonical_url":"https:\/\/prohoster.info\/cs\/blog\/administrirovanie\/tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete","robots":"max-image-preview:large","keywords":"","webmasterTools":{"miscellaneous":""},"schema":null,"og:locale":"cs_CZ","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.","og:url":"https:\/\/prohoster.info\/cs\/blog\/administrirovanie\/tcp-steganografiya-ili-kak-skryt-peredachu-dannyh-v-internete","og:image":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:secure_url":"https:\/\/prohoster.info\/wp-content\/uploads\/2021\/11\/logo-350.jpg","og:image:width":350,"og:image:height":350,"article:published_time":"2019-10-31T18:39:19+00:00","article:modified_time":"2019-10-31T18:39:19+00:00","article:publisher":"https:\/\/www.facebook.com\/prohoster","article:author":"https:\/\/www.facebook.com\/prohoster"},"aioseo_meta_data":{"post_id":"31079","title":null,"description":null,"keywords":null,"keyphrases":null,"primary_term":null,"canonical_url":null,"og_title":null,"og_description":null,"og_object_type":"default","og_image_type":"default","og_image_url":null,"og_image_width":null,"og_image_height":null,"og_image_custom_url":null,"og_image_custom_fields":null,"og_video":null,"og_custom_url":null,"og_article_section":null,"og_article_tags":null,"twitter_use_og":false,"twitter_card":"default","twitter_image_type":"default","twitter_image_url":null,"twitter_image_custom_url":null,"twitter_image_custom_fields":null,"twitter_title":null,"twitter_description":null,"schema":{"blockGraphs":[],"customGraphs":[],"default":{"data":{"Article":[],"Course":[],"Dataset":[],"FAQPage":[],"Movie":[],"Person":[],"Product":[],"ProductReview":[],"Car":[],"Recipe":[],"Service":[],"SoftwareApplication":[],"WebPage":[]},"graphName":"","isEnabled":true},"graphs":[]},"schema_type":null,"schema_type_options":null,"pillar_content":false,"robots_default":true,"robots_noindex":false,"robots_noarchive":false,"robots_nosnippet":false,"robots_nofollow":false,"robots_noimageindex":false,"robots_noodp":false,"robots_notranslate":false,"robots_max_snippet":null,"robots_max_videopreview":null,"robots_max_imagepreview":"large","priority":null,"frequency":null,"local_seo":null,"seo_analyzer_scan_date":"2026-01-21 04:26:19","breadcrumb_settings":null,"limit_modified_date":false,"reviewed_by":null,"ai":null,"created":"2021-03-01 03:22:35","updated":"2026-01-21 04:26:19","focus_keyword":null,"additional_keywords":null,"truseo_locale":null},"gt_translate_keys":[{"key":"link","format":"url"}],"_links":{"self":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/31079","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/comments?post=31079"}],"version-history":[{"count":0,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/posts\/31079\/revisions"}],"wp:attachment":[{"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/media?parent=31079"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/categories?post=31079"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/prohoster.info\/cs\/wp-json\/wp\/v2\/tags?post=31079"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}