{"id":12,"date":"2016-05-10T21:44:13","date_gmt":"2016-05-10T20:44:13","guid":{"rendered":"http:\/\/www.ict.mazuch.net\/subdom\/ict\/?page_id=12"},"modified":"2016-05-15T17:14:00","modified_gmt":"2016-05-15T16:14:00","slug":"4-elektronicka-posta-e-mail","status":"publish","type":"page","link":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/4-elektronicka-posta-e-mail\/","title":{"rendered":"(4) Elektronick\u00e1 po\u0161ta (e-mail)"},"content":{"rendered":"<div class=\"pdfprnt-buttons pdfprnt-buttons-page pdfprnt-top-right\"><a href=\"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/pages\/12?print=pdf\" class=\"pdfprnt-button pdfprnt-button-pdf\" target=\"_blank\"><img src=\"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-content\/plugins\/pdf-print\/images\/pdf.png\" alt=\"image_pdf\" title=\"View PDF\" \/><\/a><a href=\"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/pages\/12?print=print\" class=\"pdfprnt-button pdfprnt-button-print\" target=\"_blank\"><img src=\"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-content\/plugins\/pdf-print\/images\/print.png\" alt=\"image_print\" title=\"Print Content\" \/><\/a><\/div><div class=\"su-spoiler su-spoiler-style-fancy su-spoiler-icon-plus-circle su-spoiler-closed\" data-scroll-offset=\"0\" data-anchor-in-url=\"no\"><div class=\"su-spoiler-title\" tabindex=\"0\" role=\"button\"><span class=\"su-spoiler-icon\"><\/span>Osnova<\/div><div class=\"su-spoiler-content su-u-clearfix su-u-trim\">\n<ol>\n<li>Vymezen\u00ed pojmu<\/li>\n<li>Podoba emailu\n<ol>\n<li>po\u017eadavky emailu<\/li>\n<li>Emailov\u00e1 adresa<\/li>\n<\/ol>\n<\/li>\n<li>Princip fungov\u00e1n\u00ed emailu<\/li>\n<li>Bezpe\u010dnost\n<ol>\n<li>Elektronick\u00fd podpis<\/li>\n<li>\u0160ifrov\u00e1n\u00ed<\/li>\n<\/ol>\n<\/li>\n<\/ol>\n<\/div><\/div>\n<ul>\n<li>E-mail, neboli elektronick\u00fd email. Jedn\u00e1 se o zp\u016fsob pos\u00edl\u00e1n\u00ed elektronick\u00fdch dopis\u016f nebo zpr\u00e1v mezi jednotliv\u00fdmi u\u017eivateli.<\/li>\n<li>Elektronick\u00e1 po\u0161ta b\u00fdv\u00e1 zprost\u0159edkov\u00e1na pomoc\u00ed r\u016fzn\u00fdch typ\u016f po\u0161tovn\u00edch program\u016f (<strong>Mozzila, Tunderbird, Outlook<\/strong>). P\u0159i\u010dem\u017e p\u0159i provozov\u00e1n\u00ed t\u00e9to internetov\u00e9 slu\u017eby nez\u00e1le\u017e\u00ed na tom, jak\u00fd po\u0161tovn\u00ed program vyu\u017e\u00edv\u00e1 odes\u00edlatel a jak\u00fd p\u0159\u00edjemce.\n<ul>\n<li>Po\u0161tovn\u00ed program je ur\u010den k\u00a0v\u00fdm\u011bn\u011b, p\u0159\u00edjmu, odes\u00edl\u00e1n\u00ed a spr\u00e1v\u011b elektronick\u00e9 po\u0161ty p\u0159\u00edmo z\u00a0plochy po\u010d\u00edta\u010de.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h2><strong>Podoba emailu\u00a0(zpr\u00e1vy jako takov\u00e9)<\/strong><\/h2>\n<ul>\n<li>E-mailov\u00e1 zpr\u00e1va je nej\u010dast\u011bji v\u00a0podob\u011b textu. Av\u0161ak lze k\u00a0t\u00e9to zpr\u00e1v\u011b d\u00e1le p\u0159ipojovat dal\u0161\u00ed soubory, obr\u00e1zky atd.<\/li>\n<li>Bohu\u017eel \u010dasto poskytovatel\u00e9 t\u00e9to slu\u017eby nedovoluj\u00ed posl\u00e1n\u00ed p\u0159\u00edli\u0161 velk\u00e9ho objemu dat. Nej\u010dast\u011bji okolo 30 mb.<\/li>\n<\/ul>\n<ul>\n<li><strong>P\u0159i odes\u00edl\u00e1n\u00ed zpr\u00e1vy zad\u00e1v\u00e1me:<\/strong>\n<ul>\n<li>Komu pos\u00edl\u00e1me zpr\u00e1vu\/ pop\u0159\u00edpad\u011b skupinu p\u0159\u00edjemc\u016f (<strong>pomoc\u00ed e-mailov\u00e9 adresy<\/strong>)<\/li>\n<li>Hlavi\u010dku\/ p\u0159edm\u011bt zpr\u00e1vy<\/li>\n<li>P\u0159ipojen\u00fd soubor<\/li>\n<li>Vlastn\u00ed zpr\u00e1vu\/ text<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><strong>\u00a0<\/strong><\/p>\n<ul>\n<li>Po naps\u00e1n\u00ed zpr\u00e1vy je zpr\u00e1va vlo\u017eena do \u201epo\u0161tovn\u00ed schr\u00e1nky\u201c odkud je posl\u00e1n do schr\u00e1nky p\u0159\u00edjemce =&gt; po\u010d\u00edta\u010d p\u0159ipojen do s\u00edt\u011b nejprve p\u0159e\u010dte informaci, kam m\u00e1 b\u00fdt po\u0161ta odesl\u00e1na, a pot\u00e9 ji po\u0161le nejlep\u0161\u00ed mo\u017enou cestou (p\u0159i\u010dem\u017e nejlep\u0161\u00ed neznamen\u00e1 nejkrat\u0161\u00ed, p\u0159ihl\u00ed\u017e\u00ed k\u00a0zat\u00ed\u017eenosti s\u00edt\u011b a kvalit\u011b spojen\u00ed)<\/li>\n<\/ul>\n<p><strong>\u00a0<\/strong><\/p>\n<ul>\n<li><strong>E-mailov\u00e1 adresa<\/strong>\n<ul>\n<li>Jedn\u00e1 se asi o nejd\u016fle\u017eit\u011bj\u0161\u00ed \u00fadaj p\u0159i pou\u017e\u00edv\u00e1n\u00ed t\u00e9to slu\u017eby. E-mailov\u00e1 adresa p\u0159esn\u011b ozna\u010duje \u00fa\u010dastn\u00edka elektronick\u00e9 po\u0161ty.<\/li>\n<li>E-mailov\u00e1 adresa m\u00e1 tvar: <strong>\u201ejm\u00e9no\u201c <\/strong><strong>@ \u201edom\u00e9nov\u00e1 adresa\/jm\u00e9no organizace poskytuj\u00edc\u00ed slu\u017ebu\u201c<\/strong><\/li>\n<\/ul>\n<\/li>\n<li><strong>Emailov\u00e1 adresa (2)<\/strong>\n<ul>\n<li>e-mailov\u00e1 adresa m\u00e1 t\u0159i \u010d\u00e1sti \u21d2 m\u00edstn\u00ed \u010d\u00e1st adresy (p\u0159\u00edjemce) + znak zavin\u00e1\u010d + internetov\u00e1 dom\u00e9na<\/li>\n<li><u>M\u016f\u017ee b\u00fdt slo\u017eena z<\/u>: p\u00edsmena anglick\u00e9 abecedy, vybran\u00e1 interpunk\u010dn\u00ed znam\u00e9nka (te\u010dka, spojovn\u00edk, podtr\u017e\u00edtko); <u>NE<\/u>: p\u00edsmena jin\u00fdch abeced, p\u00edsmena s diakritikou, mezera<\/li>\n<li>Modern\u00ed internetov\u00e1 adresa m\u00e1 tvar <em>mistourceni@domena.priklad.cz<\/em>,\n<ul>\n<li>\u010d\u00e1st p\u0159ed znakem @ je<span style=\"text-decoration: underline;\"> m\u00edstn\u00ed \u010d\u00e1st adresy<\/span>, \u010dasto<span style=\"text-decoration: underline;\"> u\u017eivatelsk\u00e9 jm\u00e9no<\/span> p\u0159\u00edjemce zpr\u00e1vy,<\/li>\n<li>\u010d\u00e1st za @ je internetov\u00e1 dom\u00e9na. Server <span id=\"su_tooltip_6a2efebfb2f7e_button\" class=\"su-tooltip-button su-tooltip-button-outline-yes\" aria-describedby=\"su_tooltip_6a2efebfb2f7e\" data-settings='{\"position\":\"top\",\"behavior\":\"hover\",\"hideDelay\":0}' tabindex=\"0\">MTA\u2191<\/span><span style=\"display:none;z-index:100\" id=\"su_tooltip_6a2efebfb2f7e\" class=\"su-tooltip\" role=\"tooltip\"><span class=\"su-tooltip-inner su-tooltip-shadow-yes\" style=\"z-index:100;background:#FFFFFF;color:#333333;font-size:16px;border-radius:5px;text-align:left;max-width:300px;line-height:1.25\"><span class=\"su-tooltip-title\">Mail transfer agent<\/span><span class=\"su-tooltip-content su-u-trim\">Mail transfer agent neboli MTA (naz\u00fdv\u00e1n tak\u00e9 mail transport agent, message transfer agent, mail server nebo mail exchange (MX) v souvislosti s DNS) je po\u010d\u00edta\u010dov\u00fd program, kter\u00fd p\u0159en\u00e1\u0161\u00ed elektronickou po\u0161tu z jednoho po\u010d\u00edta\u010de na druh\u00fd<\/span><\/span><span id=\"su_tooltip_6a2efebfb2f7e_arrow\" class=\"su-tooltip-arrow\" style=\"z-index:100;background:#FFFFFF\" data-popper-arrow><\/span><\/span> vyhled\u00e1 n\u00e1zev dom\u00e9ny v Domain Name System (DNS), aby zjistil mail exchange servery p\u0159ij\u00edmaj\u00edc\u00ed po\u0161tu pro danou dom\u00e9nu.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p><span style=\"color: #999999;\"><em>\u00a0Znak @ na odd\u011blen\u00ed jm\u00e9na u\u017eivatele od n\u00e1zvu stroje za\u010dal pou\u017e\u00edvat Ray Tomlinson roku 1972, a to v r\u00e1mci syst\u00e9mu ARPANET, kter\u00fd vznikl v roce 1969.<\/em><\/span><\/p>\n<h2>Princip fungov\u00e1n\u00ed emailu<\/h2>\n<ul>\n<li>Internetov\u00fd syst\u00e9m po\u0161ty je zalo\u017een na n\u011bkolika standardizovan\u00fdch protokolech, zejm\u00e9na na protokolu SMTP (simple mail transfer protocol); (protokol = standard\/ zp\u016fsob vymezuj\u00edc\u00ed pravidla vz\u00e1jemn\u00e9 komunikace mezi dv\u011bma body). Tento protokol je dostupn\u00fd ve v\u0161ech s\u00edt\u00edch architektury TCP\/IP (sada protokol\u016f pro komunikaci v\u00a0po\u010d\u00edta\u010dov\u00e9 s\u00edti)<\/li>\n<\/ul>\n<p><strong>\u00a0<\/strong><\/p>\n<ul>\n<li>Mezi po\u010d\u00edta\u010di p\u0159ipojen\u00fdch k\u00a0s\u00edti prob\u00edh\u00e1 v\u00fdm\u011bna zpr\u00e1v. V\u00fdm\u011bna prob\u00edh\u00e1 jednak mezi po\u010d\u00edta\u010dem a po\u0161tovn\u00edm serverem a jednak mezi po\u0161tovn\u00edmi servery.<\/li>\n<\/ul>\n<p><strong>=&gt;<\/strong><\/p>\n<ul>\n<li>Ka\u017ed\u00fd u\u017eivatel m\u00e1 nainstalovan\u00fd program (tzv. e-mailov\u00fd klient) pop\u0159\u00edpad\u011b p\u0159istupuj\u00ed k\u00a0po\u0161t\u011b pomoc\u00ed webov\u00e9ho rozhran\u00ed.<\/li>\n<li>E-mailov\u00fd klient stahuje po\u0161tu pomoc\u00ed protokolu <strong>POP3<\/strong> (Post office protocol) nebo <strong>IMAP<\/strong> (Internet message acces protocol) =&gt; pro odes\u00edl\u00e1n\u00ed zpr\u00e1v z\u00a0klienta na server, pop\u0159\u00edpad\u011b pos\u00edl\u00e1n\u00ed mezi servery slou\u017e\u00ed protokol <strong>SMTP<\/strong>, server potom pomoc\u00ed DNS najde adresu serveru na kter\u00fd m\u00e1 poslat e-mail<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<ul>\n<li><u>Komunikace mezi klientem a serverem:<\/u>\n<ul>\n<li>1) klient\/ u\u017eivatel navazuje spojen\u00ed na portu 25, pokud je v\u0161e v\u00a0po\u0159\u00e1dku server odpov\u00ed \u010d\u00edselnou odpov\u011bd\u00ed (220)<\/li>\n<li>2) klient d\u00e1le ode\u0161le serveru p\u0159\u00edkaz se svou identifikac\u00ed, pokud je server ochoten p\u0159ij\u00edmat zpr\u00e1vy od tohoto klienta, odpov\u00ed op\u011bt \u010d\u00edselnou odpov\u011bd\u00ed (250)<\/li>\n<li>3) odesl\u00e1n\u00ed specifikace odes\u00edlatele a p\u0159\u00edjemce po\u0161ty<\/li>\n<li>4) odesl\u00e1n\u00ed vlastn\u00edho t\u011bla zpr\u00e1vy<\/li>\n<li>5) po \u00fasp\u011b\u0161n\u00e9m p\u0159enosu zpr\u00e1vy n\u00e1sleduje potvrzen\u00ed a ukon\u010den\u00ed spojen\u00ed<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<h2><strong>Bezpe\u010dnost<\/strong><\/h2>\n<ul>\n<li>P\u0159i pou\u017e\u00edv\u00e1n\u00ed internetov\u00fdch slu\u017eeb jako je e-mail mus\u00edme db\u00e1t na bezpe\u010dnost, jeliko\u017e m\u016f\u017ee v\u00a0n\u011bkter\u00fdch p\u0159\u00edpadech doj\u00edt k\u00a0\u00faniku citliv\u00fdch informac\u00ed.<\/li>\n<li><u>Pro bezpe\u010dnost vyu\u017e\u00edv\u00e1n\u00ed e-mailu pou\u017e\u00edv\u00e1me n\u011bkolik n\u00e1stroj\u016f:<\/u><\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<ul>\n<li><strong>Elektronick\u00fd podpis<\/strong>\n<ul>\n<li>Jedn\u00e1 se zde o n\u00e1stroj, kdy pomoc\u00ed speci\u00e1ln\u00edho k\u00f3du p\u0159ipojen\u00e9ho ke zpr\u00e1v\u011b je mo\u017en\u00e9 ov\u011b\u0159it to, kdo zpr\u00e1vu skute\u010dn\u011b odeslal a to \u017ee obsah zpr\u00e1vy nebyl nijak pozm\u011bn\u011bn.<\/li>\n<\/ul>\n<\/li>\n<li><strong>\u0160ifrov\u00e1n\u00ed<\/strong>\n<ul>\n<li>N\u011bkter\u00e9 servery si ukl\u00e1daj\u00ed kopie na\u0161ich e-mail\u016f, proto lze pou\u017e\u00edt programy ur\u010den\u00e9 k\u00a0jejich za\u0161ifrov\u00e1n\u00ed. (PGP, GNU Privacy Guard)<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<ul>\n<li>Bezpe\u010dnostn\u00ed riziko p\u0159edstavuje taky spam a hoax a e-mailov\u00fd \u010derv\n<ul>\n<li><strong>Spam<\/strong> \u2013 jedn\u00e1 se o nevy\u017e\u00e1danou po\u0161tu, \u010dasto s\u00a0reklamn\u00edm obsahem, v\u00a0ur\u010dit\u00fdch p\u0159\u00edpadech kdy dojde k\u00a0velk\u00e9mu p\u0159\u00edjmu t\u011bchto zpr\u00e1v, m\u016f\u017ee doj\u00edt<\/li>\n<li><strong>Hoax<\/strong> \u2013 jedn\u00e1 se o podvodnou zpr\u00e1vu, \u010dasto varuje u\u017eivatele p\u0159ed n\u011bjak\u00fdm virem, nebo pros\u00ed o pomoc a \u017e\u00e1d\u00e1 tak o dal\u0161\u00ed rozesl\u00e1n\u00ed t\u00e9to zpr\u00e1vy.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<ul>\n<li><em>P\u0159\u00edklad hoaxu:<\/em>\n<ul>\n<li><em>Nep\u0159id\u00e1vejte si do kontakt listu na ICQ u\u017eivatele xxx-xxx-xxx. Je to vir a po ud\u011blen\u00ed autorizace v\u00e1m sma\u017ee v\u0161echna data na disku, v\u010detn\u011b kontakt\u016f na ICQ a automaticky se roze\u0161le v\u0161em va\u0161im p\u0159\u00e1tel\u016fm.<\/em><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>&nbsp;<\/p>\n<ul>\n<li><strong>Po\u010d\u00edta\u010dov\u00fd \u010derv<\/strong> \u2013 jedn\u00e1 se o po\u010d\u00edta\u010dov\u00fd program, kter\u00fd je schopen automatick\u00e9ho rozes\u00edl\u00e1n\u00ed sv\u00fdch kop\u00ed\u00ed na dal\u0161\u00ed po\u010d\u00edta\u010de. (sna\u017e\u00ed se p\u0159evz\u00edt prost\u0159edky zodpov\u011bdn\u00e9 za s\u00ed\u0165ovou komunikaci, sekund\u00e1rn\u011b se sna\u017e\u00ed o zneprovozn\u011bn\u00ed po\u010d\u00edta\u010de, odstra\u0148ov\u00e1n\u00ed soubor\u016f, prohled\u00e1v\u00e1n\u00ed po\u010d\u00edta\u010de za \u00fa\u010delem z\u00edsk\u00e1n\u00ed osobn\u00edch dat, vytvo\u0159en\u00ed tzv. \u201ezadn\u00edch vr\u00e1tek\u201c, kter\u00e1 umo\u017en\u00ed d\u00e1le infikovat po\u010d\u00edta\u010d)\n<ul>\n<li>P\u0159es e-mail se tak lze nakazit otev\u0159en\u00edm a sta\u017een\u00edm p\u0159ilo\u017een\u00e9 p\u0159\u00edlohy, \u010di otev\u0159en\u00edm nezn\u00e1m\u00fdch odkaz\u016f.<\/li>\n<\/ul>\n<\/li>\n<li><strong>Virus<\/strong>\n<ul>\n<li>Virus je typ programu, kter\u00fd se dok\u00e1\u017ee s\u00e1m \u0161\u00ed\u0159it t\u00edm, \u017ee vytv\u00e1\u0159\u00ed (n\u011bkdy upraven\u00e9) kopie sebe sama. Hlavn\u00edm krit\u00e9riem pro posouzen\u00ed programu jako viru je fakt, \u017ee k \u0161\u00ed\u0159en\u00ed vyu\u017e\u00edv\u00e1 jin\u00e9 soubory \u2013 hostitele. Virus se mezi dv\u011bma po\u010d\u00edta\u010di m\u016f\u017ee p\u0159en\u00e9st jedin\u011b t\u00edm, \u017ee n\u011bkdo p\u0159enese cel\u00e9ho hostitele, nap\u0159. n\u011bjak\u00fd u\u017eivatel (obvykle ne\u00famysln\u011b) p\u0159enese soubor na disket\u011b \u010di CD-ROM nebo ho po\u0161le prost\u0159ednictv\u00edm po\u010d\u00edta\u010dov\u00e9 s\u00edt\u011b.<\/li>\n<li><a href=\"https:\/\/cs.wikipedia.org\/wiki\/Po%C4%8D%C3%ADta%C4%8Dov%C3%BD_virus\">https:\/\/cs.wikipedia.org\/wiki\/Po%C4%8D%C3%ADta%C4%8Dov%C3%BD_virus<\/a><\/li>\n<\/ul>\n<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>E-mail, neboli elektronick\u00fd email. Jedn\u00e1 se o zp\u016fsob pos\u00edl\u00e1n\u00ed elektronick\u00fdch dopis\u016f nebo zpr\u00e1v mezi jednotliv\u00fdmi u\u017eivateli. Elektronick\u00e1 po\u0161ta b\u00fdv\u00e1 zprost\u0159edkov\u00e1na pomoc\u00ed r\u016fzn\u00fdch typ\u016f po\u0161tovn\u00edch program\u016f (Mozzila, Tunderbird, Outlook). P\u0159i\u010dem\u017e p\u0159i provozov\u00e1n\u00ed t\u00e9to internetov\u00e9 slu\u017eby nez\u00e1le\u017e\u00ed na tom, jak\u00fd po\u0161tovn\u00ed program vyu\u017e\u00edv\u00e1 odes\u00edlatel a jak\u00fd p\u0159\u00edjemce. Po\u0161tovn\u00ed program je ur\u010den k\u00a0v\u00fdm\u011bn\u011b, p\u0159\u00edjmu, odes\u00edl\u00e1n\u00ed a spr\u00e1v\u011b elektronick\u00e9 <a class=\"read-more\" href=\"https:\/\/www.ict.mazuch.net\/subdom\/ict\/4-elektronicka-posta-e-mail\/\">[&hellip;]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"wppr_data":[],"_links":{"self":[{"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/pages\/12"}],"collection":[{"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/comments?post=12"}],"version-history":[{"count":6,"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/pages\/12\/revisions"}],"predecessor-version":[{"id":122,"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/pages\/12\/revisions\/122"}],"wp:attachment":[{"href":"https:\/\/www.ict.mazuch.net\/subdom\/ict\/wp-json\/wp\/v2\/media?parent=12"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}