POP3 - popis pouziti protokolu

POP3 protokol je protokol pouzivany k vyzvedavani mailu z postovniho serveru pres TCP/IP spojeni. Specifikace tohoto protokolu je popsana v http://www.ietf.org/rfc/rfc1939.txt. Tento protokol obsahuje prikazy: QUIT, STAT, RETR, DELE, NOOP, RSET, TOP, UIDL, USER, PASS, APOP a dva vysledne stavy: +OK probehne-li prikaz uspesne a -ERR pri neuspechu
Prubeh relace se sklada ze tri stavu: Autorizacni (authorization), Transkacni (transaction), a Update (update). V autorizacni fazi dojde pomoci prikazu USER a PASS k overeni identity uzivatele. V nasledne transakcni fazi muzeme pomoci prikazu STAT, LIST, RETR, DELE manipulovat se zpravami ulozenymi na serveru a po ukonceni teto faze pomoci prikazu QUIT prejde spojeni do update faze, zde dojde ke skutecnemu smazani zprav, ktere jsme predtim pomoci DELE oznacili ke smazani.
Standardne tento protokol je pristupny na portu 110, popr. 995 pro sifrovana spojeni.

vysvetleni jednotlivych prikazu:

------ Autorizacni faze -------
USER userName : uzivatelske jmeno (login) uzivatele, do jehoz schranky chceme pristupovat
PASS password : heslo. pokud heslo odpovida zadanemu loginu, dostaneme odpoved +OK logged in, jinak -ERR Login failed (chybove hlasky se zrejme mohou lisit u ruznych POP3 serveru)

------ Relacni faze -------
STAT : vypise stav mailboxu, pocet zprav a jejich velikost
LIST : vypise podrobny stav mailboxu - seznam jednotliych zprav a jejich velikosti
RETR cislo_zpravy : stahne zvolenou zpravu ze serveru
DELE cislo_zpravy : oznaci zvolenou zpravu ke smazani
RSET byly-li nejake zpravy oznaceny ke smazani, tento prikaz vsechny tyto priznaky zrusi
QUIT ukonceni relacni faze a prechod do update faze a nesledne ukonceni relace

ukazka POP3 relace

gentoo ~ # telnet agent.zlutazimnice.cz 110
Trying 81.95.102.223...
Connected to agent.zlutazimnice.cz.
Escape character is '^]'.
+OK Hello there.
user testaccount@zlutazimnice.cz
+OK Password required.
pass testovoheslo
+OK logged in.
list
+OK POP3 clients that break here, they violate STD53.
1 2363
.
retr 1
+OK 2363 octets follow.
Return-Path: <kacerr@developers.zlutazimnice.cz>
X-Original-To: testaccount@zlutazimnice.cz
Delivered-To: testaccount@zlutazimnice.cz
Received: from localhost (localhost.zlutazimnice.cz [127.0.0.1])
by agent.zlutazimnice.cz (Postfix) with ESMTP id 00BB46EF40
for <testaccount@zlutazimnice.cz>; Mon, 12 Sep 2005 05:48:35 +0200 (CEST
)
Received: from agent.zlutazimnice.cz ([127.0.0.1])
by localhost (agent.zlutazimnice.cz [127.0.0.1]) (amavisd-new, port 10024)
with ESMTP id 27578-09 for <testaccount@zlutazimnice.cz>;
Mon, 12 Sep 2005 05:48:34 +0200 (CEST)
Received: from gamedonald (dsl-tn-1-186.static.adsl.vol.cz [62.177.95.186])
by agent.zlutazimnice.cz (Postfix) with ESMTP id 7363A6EF3F
for <testaccount@zlutazimnice.cz>; Mon, 12 Sep 2005 05:48:33 +0200 (CEST
)
From: "Honza Novak" <kacerr@developers.zlutazimnice.cz>
To: <testaccount@zlutazimnice.cz>
Subject: zkusebni mail #1
Date: Mon, 12 Sep 2005 05:46:31 +0200
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0003_01C5B75D.55BE17D0"
X-Mailer: Microsoft Office Outlook, Build 11.0.5510
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1506
Thread-Index: AcW3TI+/AJ7ledyJSKeCRjWAuyPOjQ==
Message-Id: <20050912034833.7363A6EF3F@agent.zlutazimnice.cz>
X-Virus-Scanned: by amavisd-new at yfkru.zlutazimnice.cz

This is a multi-part message in MIME format.

------=_NextPart_000_0003_01C5B75D.55BE17D0
Content-Type: text/plain;
charset="us-ascii"
Content-Transfer-Encoding: 7bit

Tady posilam zkusebni mail, at tam alespon neco mas.

Honza

------=_NextPart_000_0003_01C5B75D.55BE17D0
Content-Type: text/html;
charset="us-ascii"
Content-Transfer-Encoding: quoted-printable
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML><HEAD>
<META http-equiv=3DContent-Type content=3D"text/html; =
charset=3Dus-ascii">
<META content=3D"MSHTML 6.00.2800.1515" name=3DGENERATOR></HEAD>
<BODY>
<DIV><SPAN class=3D219034603-12092005><FONT face=3DVerdana size=3D2>Tady =
posilam=20
zkusebni mail, at tam alespon neco mas.</FONT></SPAN></DIV>
<DIV><SPAN class=3D219034603-12092005><FONT face=3DVerdana=20
size=3D2></FONT></SPAN>&nbsp;</DIV>
<DIV><SPAN class=3D219034603-12092005><FONT face=3DVerdana=20
size=3D2>Honza</FONT></SPAN></DIV></BODY></HTML>

------=_NextPart_000_0003_01C5B75D.55BE17D0--

.
quit
+OK Bye-bye.
Connection closed by foreign host.