Servizi di posta elettronica

Transcription

1 Servizi di posta elettronica Serate a tema Amministrazione sistemi Linux 26 aprile 2010 Marco Moser Linuxtrent

2 Contesto

3 Termini Mail User Agent legge la posta via file, pop3, imap (mutt, thunderbird, webmail) Mail Transfer Agent riceve, spedisce, inoltra via smtp (sendmail, postfix, qmail) Mail Delivery Agent consegna la posta (procmail, deliver, lda)

4 Protocollo SMTP Simple Mail Transport Protocol (1982) Porta 25 Legge (e scrive) gli header dell' ascii a 7bit Non certifica il mittente dei messaggi ESMTP (2008) 8bit, uft8, starttls, autenticazione,...

5 Esempio SMTP telnet 25 S: 220 ESMTP Postfix C: HELO mydomain.com S: 250 Hello mydomain.com, pleased to meet you C: MAIL FROM: S: 250 Sender ok C: RCPT TO: S: 250 Recipient Ok C: DATA S: 354 End data with "." on a line by itself C: Subject: messaggio di prova C: From: C: To: C: C: Ciao, C: questa è una prova. C:. S: 250 Ok: queued as C: QUIT S: 221 Bye * wikipedia

6 Protocollo POP Post Office Protocol (ver. 3) Porta 110 (plain o starttls) oppure 995 (ssl) Autentica l'utente Elenca, mostra e cancella la posta

7 Esempio POP telnet 110 S:+OK C:USER pippo S:+OK C:PASS pluto S:+OK C:LIST S:+OK C:RETR 1 S:+OK Return-Path: Delivered-To: Date: Sat, 22 Oct :24: From: Mario Rossi Subject: xxxx Content-Type: text/plain; charset=iso testo messaggio. C:DELE 1 S:+OK C:QUIT S:+OK * wikipedia

8 Protocollo IMAP Internet Message Access Protocol (ver ) Porta 143 (plain o starttls) oppure 993 (ssl) Autentica utente instaura una sessione, consente l'accesso concorrente all'account Elenca, mostra, cancella e archivia la posta organizzazione in cartelle, flags (letta, inoltrata,..., di lavoro, urgente), primitive per la ricerca Scaricamento parziale dell' (mime) Shared folders

9 Esempio IMAP telnet imap.joker.net 143 * OK [CAPABILITY IMAP4REV1 LOGIN-REFERRALS STARTTLS AUTH=LOGIN] joker.net IMAP4rev at Sun, 13 Jul :09: (CEST) a100 LOGIN homer onslls a100 OK [CAPABILITY IMAP4REV1 IDLE NAMESPACE MAILBOX-REFERRALS SCAN SORT THREAD=REFERENCES THREAD=ORDEREDSUBJECT MULTIAPPEND] User homer authenticated a101 select inbox * 2 EXISTS a102 fetch 1:2 (flags body[header.fields (subject)])... a103 FETCH 1 (body[text]) * 1 FETCH (BODY[TEXT] {105} Messaggio di prova, Blah blah a104 STORE 1 +FLAGS (\Deleted) * 1 FETCH (FLAGS (\Seen \Deleted NonJunk)) a104 OK STORE completed a106 LOGOUT a106 OK LOGOUT completed * openskill.info

10 Esempio Return-Path: Delivered-To: Received: from smtp-out05a.alice.it (smtp-out05a.alice.it [ ]) by mail.oltrefersina.it (Postfix) with ESMTP id 4D319CF8005 for Sat, 24 Apr :37: (CEST) Received: from FBCMMO04.fbc.local ([ ]) by smtp-out05a.alice.it with Microsoft SMTPSVC( ); Sat, 24 Apr :37: Received: from FBCMCL01B02.fbc.local ([ ]) by FBCMMO04.fbc.local with Microsoft SMTPSVC( ); Sat, 24 Apr :36: Received: from [ ] ([ ]) by FBCMCL01B02.fbc.local with Microsoft SMTPSVC( ); Sat, 24 Apr :36: Message-ID: Date: Sat, 24 Apr :36: From: "Polisportiva Oltrefersina.it" User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; it; rv: ) Gecko/ Thunderbird/3.0.4 MIME-Version: 1.0 To: Polisportiva Oltrefersina Subject: prova Content-Type: text/plain; charset=iso ; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 24 Apr :36: (UTC) FILETIME=[AAAF2AD0:01CAE391] di prova

11 MIME Multipurpose Internet Mail Extensions Supporta il trasporto di mail non-ascii e multipart Header non ascii Subject: =?ISO ?Q?perch=E8_poich=E8?= Content-Transfer-Encoding: 8bit... Content-Type: multipart/mixed; boundary="----_=_nextpart_001_01c9e9b3.91ed543c" _=_NextPart_002_01C9E9B3.91ED543C Content-Type: text/plain; charset="iso " Content-Transfer-Encoding: quoted-printable

12 MTA Sendmail (Allman 1980) storico ma ostico da configurare Qmail (Berstein 1995) nasce molto sicuro (taglia 1 bug = 1.000$), da compilare, oggi la licenza e' public domain, e' un progetto fermo Postfix (IBM, Venema 1997) sicuro, flessibile e diffuso Altri: Exim, Apache James,...

13 Postfix minimale Server minimale per utenti locali (/etc/passwd) + invio al mondo apt-get install postfix mailx vi /etc/postfix/main.cf myhostname=mail.oltrefersina.it mydestination = $myhostname, localhost. $mydomain, localhost mynetworks = /8

14 Postfix minimale vi /etc/aliases root: /usr/bin/newaliases /etc/init.d/postfix restart Test mailx -s OK marcomoser prova

15 Postfix utility mailq coda messaggi postsuper -r AEF2ACF8004 rimuove dalla coda postqueue -f svuota coda tail -f /var/log/mail.info file di log /var/spool/mail/ caselle mbox

16 Postfix Alice Mail server con relay su alice business apt-get install libsasl2-modules vi /etc/postfix/main.cf myhostname=server1 mydestination = $myhostname, localhost. $mydomain, localhost mynetworks = / /24 relayhost = [mail.191.biz]

17 Postfix Alice main.cf smtp_sasl_auth_enable = yes smtp_sasl_type = cyrus smtpd_use_tls = no smtp_sasl_security_options = noanonymous # evita ntlm smtp_sasl_mechanism_filter = LOGIN smtp_sasl_password_maps = hash:/etc/postfix/sasl_passwd # logging debug_peer_list = mail.191.biz vi /etc/postfix/sasl_passwd mail.191.biz postmap /etc/postfix/sasl/sasl_passwd

18 Poor programmer - antispam Postgrey greylisting (rifiuto temporaneo) Real-time Blackhole List elenco di host sconsigliati vi main.cf smtpd_recipient_restrictions = permit_mynetworks, reject_unauth_destination, reject_rbl_client sbl.spamhaus.org, reject_rbl_client bl.spamcop.net, check_policy_service inet: :60000

19 Antispam Apache SpamAssasin bayesian: filtra la posta in ingresso valutandone il contenuto [perl] DSPAM autoapprendimento, filtri bayesian [c] + gui Amavis spamassasin + clamav (antivirus) ASSP smtp proxy server (bayesian, rbl, urirbl, greylisting, ) + gui ThunderBayes++ Thunderbird plugin

20 Utenti virtuali # Crea user vmail groupadd -g 5000 vmail useradd -m -u g s /bin/false vmail vi main.cf # elenco dei domini per cui accettare la virtual_mailbox_domains = /etc/postfix/vhosts # homedir delle caselle virtual virtual_mailbox_base = /home/vmail virtual_uid_maps = static:5000 virtual_gid_maps = static:5000 # elenca puntualmente tutte le caselle postali e directory relativa virtual_mailbox_maps = hash:/etc/postfix/vmailbox # elenca tutti gli alias virtual_alias_maps = hash:/etc/postfix/valias

21 Utenti virtuali vi /etc/postfix/vhosts oltrefersina.it vi /etc/postfix/vmailbox vi /etc/postfix/valias oltrefersina.it/info/ oltrefersina.it/moser/ oltrefersina.it/calcio/ postmap /etc/postfix/vmailbox postmap /etc/postfix/valias Postfix reload

22 Dovecot T.Sirainen, Finlandia (2002) Ubuntu , beta 2.0 server IMAP e POP3 con supporto per i protocolli sicuri IMAPS e POPS, TLS e SSL caselle di posta in entrambi i formati: mbox e Maildir. Autenticazione degli utenti passwd, pam, ldap, sql Implementa un lda con mail quota e sieve (vacation, redirect) Parla con postfix sasl (scenario server) Sicurezza taglia 1 bug = Euro

23 LDA apt-get install dovecot-imapd dovecot-pop3d vi /etc/dovecot/dovecot.conf protocols = imap imaps pop3 pop3s # outlook non ha il tls disable_plaintext_auth = no mail_location = maildir:/home/vmail/%d/%n # abilita il local delivery agent + sieve script protocol lda { # Address to use when sending rejection mails. postmaster_address = # Enabling Sieve plugin for server-side mail filtering mail_plugins = cmusieve }

24 Auth + Sieve auth default { # il methodo login e' usato da outlook (sasl) mechanisms = plain login #passdb passwd-file { # quello solo per deny = yes #passdb pam { passdb passwd-file { args = /home/dovecot/passwd-%d } userdb passwd-file { args = /home/dovecot/passwd-%d } # user needs access to only user and password databases user = root ## dovecot-lda specific settings ## socket listen { master { path = /var/run/dovecot/auth-master mode = 0600 user = vmail # User running Dovecot LDA #group = vmail # Or alternatively mode LDA user in this group } } plugin { sieve = /home/vmail/%d/%n/sieve }

25 Postfix - Dovecot vi /etc/postfix/main.cf dovecot_destination_recipient_limit = 1 virtual_transport = dovecot vi /etc/postfix/master.cf # service type private unpriv chroot wakeup maxproc command + args # dovecot lda dovecot unix - n n - - pipe flags=drhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${recipient}

26 File utenti + sieverc Vi /etc/dovecot/passwd # user:password:uid:gid:(gecos):home:(shell):extra_fields vi /home/vmail/oltrefersina.it/moser/sieverc require "fileinto"; # mailing linuxtrent if header :contains "to" { fileinto "Mailing.Linuxtrent"; stop; } if header :contains "to" { fileinto "Mailing.Soci Linuxtrent"; stop; }

27 Qmail + vpopmail + qmailadmin Vpopmail (Inter7 GPL) virtual domains, virtual users file system, sql, ldap Gui per l'amministratore e per gli utenti (forward, vacation, autoresponder) Nota dolente... si parte dai sorgenti: qmail, vpopmail, dovecot/courier-imap

28 Qmailadmin (web)

29 Mozilla Thunderbird

30 NOCC

31 RoundCube

32 Groupware Overlook (openit) rubrica, calendario (condivisi) Egroupware Zimbra Horde SugarCRM

33 Conclusioni Fonti: Licenza della presentazione: Autore: Marco Moser Licenza: Creative Commons Attribuzione - Condividi allo stesso modo 2.5 Italia License