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(Ak: Uusi sivu: smtpd_recipient_restrictions = reject_invalid_hostname, reject_unknown_recipient_domain, reject_unauth_destination, reject_rbl_client sbl.spamhaus.org, # If...)
(Ak: Uusi sivu: And this checks the list of known spam senders for cross-reference:)
Rivi 231: Rivi 231:
 
         reject_unknown_helo_hostname
 
         reject_unknown_helo_hostname
  
−
Ja tämä tarkistaa listan onko verkkotunnus merkitty roskapostittajaksi:
+
And this checks the list of known spam senders for cross-reference:
  
 
   [[nano]] /etc/postfix/main.cf
 
   [[nano]] /etc/postfix/main.cf

Versio 21. heinäkuuta 2015 kello 06.18

Muut kielet:
English • ‎suomi

Postfix is a free and open source mail transfer agent (MTA). Postfix is secure, performs well and has good spam filtering options.

We also recommend you to use Spamassassin and Amavis to protect mail servers from spammers.

Installation

 aptitude install postfix

Follow the installation programs instructions.

Postfix1.png


After this you need to give the servers host name.

For example: 

 mail.example.com

Configuration

Open the configuration file: 

 nano /etc/postfix/main.cf

Check that the postfix configuration file has defined the computers' host name and server address. 

 myhostname = server.example.com
 alias_maps = hash:/etc/aliases
 alias_database = hash:/etc/aliases
 myorigin = example.com
 mydestination = example.com, server.example.com, localhost, localhost.example.com$
 #relayhost =
 mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
 mailbox_command = procmail -a "$EXTENSION"
 mailbox_size_limit = 0
 recipient_delimiter = +
 inet_interfaces = all

Save the file and then open the next file 

 nano /etc/postfix/master.cf

By default, normal SMTP connections are allowed in port 25 by the master.cf file. 

 smtp      inet  n       -       -       -       -       smtpd


By default the next lines will be marked by a number sign (#).

Enable SMTP transfer in port 587 by erasing the number sign. It can also transfer encrypted traffic with the STARTTLS command. 

 submission inet n       -       -       -       -       smtpd
   -o syslog_name=postfix/submission
   -o smtpd_tls_security_level=encrypt
   -o smtpd_sasl_auth_enable=yes
   -o smtpd_client_restrictions=permit_sasl_authenticated,reject
   -o milter_macro_daemon_name=ORIGINATING

Enable SMTPS traffic in port 465 by removing the number sign. SSL encryption is enabled by default in this connection. SASL certification is recommended to be used. 

 smtps     inet  n       -       -       -       -       smtpd
   -o syslog_name=postfix/smtps
   -o smtpd_tls_wrappermode=yes
   -o smtpd_sasl_auth_enable=yes
   -o smtpd_client_restrictions=permit_sasl_authenticated,reject
   -o milter_macro_daemon_name=ORIGINATING

Explanations:

Your servers' name (make sure it is the same as hostname (command: hostname)): 

 myhostname = server.example.com

Log in credentials = Same as Debian. Let's not change. 

 alias_maps = hash:/etc/aliases
 alias_database = hash:/etc/aliases

Domain (define your server into a mail address [email protected]). By default there is defined /etc/mailname: 

 myorigin = example.com

Computer host names: 

 mydestination = example.com, server.example.com, localhost, localhost.example.com$
 #relayhost = 127.0.0.1:10111

This is required if you don't have direct connection to the network.

As example, a mail server from Sonera: 

 relayhost = [mail.inet.fi]:25

DNA post server: 

 relayhost = [smtp.dnainternet.net]:25


Your local network: 

 mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
 mailbox_command = procmail -a "$EXTENSION"
 mailbox_size_limit = 0
 recipient_delimiter = +

Network connections: 

 inet_interfaces = all

Close the file and restart postfix. 

 service postfix restart

Additional settings

Virtual e-mail addresses

You can direct your virtual mail addresses e.g. [email protected] and [email protected] to your own user.

Open the file: 

 /etc/aliases

# /etc/aliases
mailer-daemon: postmaster
postmaster: root
nobody: root
hostmaster: root
usenet: root
news: root
webmaster: root
www: root
ftp: root
abuse: root
noc: root
security: root
root = [username]

By changing [username] into your own account, you can get all the mail from these user accounts in the same inbox. You can add other addresses to the end of the file: 

[alias_postname] = [touser]

Confirm changes 

 newaliases

Virtual domains

Virtualdomains are meant for mail servers that send and receive for multiple different domains.


Open the postfix configuration file main.cf 

 /etc/postfix/main.cf

Add the following lines: 

 virtual_alias_domains = example.com
 virtual_alias_maps = hash:/etc/postfix/virtual

Create a new file 

 [email protected] postmaster
 [email protected]       matti
 [email protected]      kalle
 # Uncomment entry below to implement a catch-all address
 # @example.com         aleksi

Don't add virtual_alias_domain as a mydestination domain!

Mail redirection

For example, how to redirect mail from [email protected] to matti.example2.com

Open the postfix configuration file main.cf 

 /etc/postfix/main.cf:

Add the following lines into the file: 

   virtual_alias_domains = example.com
   virtual_alias_maps = hash:/etc/postfix/virtual

Create a new file 

 /etc/postfix/virtual:

Add the following lines into the file 

  [email protected] postmaster
  [email protected]        [email protected]
  [email protected]       [email protected]
  # Uncomment entry below to implement a catch-all address
  # @example.com         jim@yet-another-site

The domain of mail to be redirected must also be mydestination marked. You can't, for instance, redirect aliases /etc/alias

Check configuration 

  postmap /etc/postfix/virtual

Test Postfix functionality

We send a test mail:

Install this e-mail tool if you haven't done so yet: 

 apt-get install mailutils

and after that we send some mail: 

 mail [email protected]

The command will print: 

Subject: your mail's topic or headline

After this write your message and hit enter, and it will print: 

 CC:

Which you can leave blank. Send the mail by the keyboard combination CTRL+D.

Protecting your mail server

When you create your own mail server, you must immediately set up basic protection to cover yourself from spammers. We also recommend that you enable SASL proofing.

Filtering spam

By adding a few lines to the configuration we can verify if the sender's host name / domain actually exists, and block it if it doesn't. 

 nano /etc/postfix/main.cf



 smtpd_recipient_restrictions = reject_invalid_hostname,
       reject_unknown_recipient_domain,
       reject_unauth_destination,
       reject_rbl_client sbl.spamhaus.org, # If your provider is Sonera, do not add this line
       permit

smtpd_helo_restrictions = reject_invalid_helo_hostname,
       reject_non_fqdn_helo_hostname,
       reject_unknown_helo_hostname

And this checks the list of known spam senders for cross-reference: 

 nano /etc/postfix/main.cf

 smtpd_client_restrictions = reject_rbl_client dnsbl.sorbs.net

SMTPS SASL todennus

Lisäämällä seuraava rivi, niin estät sähköpostin välitykset muusta kuin omasta verkostasi. SASL tunnistuksen avulla voit lähettää muustakin verkosta 

 nano /etc/postfix/main.cf

 smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject

 nano /etc/postfix/master.cf

Ota seuraavilta riveiltä risuaita pois submission ja smtps kohdasta. Jos haluat SMTP portille myös audikoinnin, lisää tämä seuraavat rivi sen alle. 

 -o smtpd_sasl_auth_enable=yes
 -o smtpd_client_restrictions=permit_sasl_authenticated,reject

TLS (STARTSSL)

Esimerkki konfiguraatio tiedostosta /etc/postfix/main.cf 

smtpd_tls_cert_file = /etc/postfix/cert.pem
smtpd_tls_key_file = /etc/postfix/key.pem
smtpd_tls_mandatory_ciphers = high
smtpd_tls_mandatory_exclude_ciphers = aNULL, MD5
smtpd_tls_security_level = encrypt
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_mandatory_protocols = TLSv1 TLSv1.1 TLSv1.2
smtpd_tls_ask_ccert = yes
smtp_tls_fingerprint_digest = sha1
smtpd_use_tls=yes

Ota käyttöön Submission kohdasta risuaidat pois.

Testaa STARTSSL: https://starttls.info/

ja

http://checktls.com/

SMTPS

Postfixissä on tuki SSL yhteydelle TLS:n kanssa mutta ei pelkästään SSL kanssa. Tämä seuraava ohje siis on pelkälle SSL, mutta jos on tuki TLS salaukselle, on suositeltavaa käyttää sitä.

Ohjeen lähde: http://www5.sonera.fi/keskustele/viewtopic.php?f=59&t=9210

SMTPS on salattu SMTP yhteys ja nykyisin suositus olisi käyttää tätä ominaisuutta.

Esimerkkinä on Soneran verkko:

Olet siis konfiguroinnut /etc/postfix/main.cf tiedostoon. Tämä siis toimii salaamattassa portissa 25. 

 relayhost = [mail.inet.fi]

Nyt olisi aika siirtyä salattuun postiin ja tämä on hieman hankalempi, kun Soneran omat postipalvelimet eivät tue TLS salausta. Postfix ei tue SSL salausta, mutta asennetaan pieni kiertotie niin se onnistuu.

Asennetaan ensin Stunnel 

 aptitude install stunnel

Luodaan tiedosto /etc/stunnel/postfix.conf ja kopioi alla oleva koodi: 

 [ssmtp_c2s]
   accept = 127.0.0.1:10111
   client = yes
   connect = mail.inet.fi:465
   delay = yes

ja tämän jälkeen avaa tiedosto: /etc/default/stunnel ja muuta se seuraavanlaiseksi: 

 # Change to one to enable stunnel automatic startup
 # MUUTOS
 #ENABLED=0
 ENABLED=1
 FILES="/etc/stunnel/*.conf"
 OPTIONS=""
 
 # Change to one to enable ppp restart scripts
 PPP_RESTART=0

Tämän jälkeen muokkaa /etc/postfix/main.cf seuraavanlaiseksi: 

 relayhost = 127.0.0.1:10111
   
 # SASL authentication
 smtp_sasl_auth_enable=yes
 smtp_sasl_password_maps = hash:/etc/postfix/passwd
 smtp_sasl_security_options = noanonymous
 smtp_sasl_tls_security_options = noanonymous
    
 # TLS
 smtp_tls_eccert_file =
 smtp_tls_eckey_file =
 # http://www.postfix.org/TLS_README.html#client_tls_may
 smtp_tls_security_level = may
 smtpd_tls_received_header = yes
tls_random_source = dev:/dev/urandom
 # http://www.postfix.org/TLS_README.html#client_tls_may
 smtpd_tls_security_level = may

Luo tiedosto /etc/postfix/passwd ja kirjoita siihen Soneran sähköpostisi käyttäjätunnus ja salasana 

 mail.inet.fi:465 KÄYTTÄJÄTUNNUS:SALASANA

Esimerkiksi: 

 mail.inet.fi:465 [email protected]:taisto

Tämän jälkeen anna tämä komento: 

 postmap hash:/etc/postfix/passwd

Kokeile toimiiko antamalla seuraava komento: 

 postmap -q mail.inet.fi:465 /etc/postfix/passwd

Jos komento tulostaa käyttäjätunnuksesi ja salasanasi, kaikki toimii tähän asti


Estä muiden käyttäjien näkemästä salasanaasi: 

 chmod go-rwx /etc/postfix/passwd*

Käynnistä lopuksi palvelut uudelleen 

 service stunnel4  restart

 service postfix restart


Postfix toiminta PHP5 kanssa

PHP5 sisältää mail funktion. Sinun tulee konfiguroida php.ini tiedostoa 

 nano /etc/php5/apache2/php.ini

ja muuttaa se tälläiseksi: 

 ; For Unix only.  You may supply arguments as well (default: "sendmail -t -i").
 ; http://php.net/sendmail-path
 sendmail_path = "/usr/sbin/sendmail -t -i"

ja käynnistä apache uudelleen 

 service apache2 restart

Virheilmoituksia

Tässä lista yleisistä virheilmoituksista mitä ilmenee usein postfixin konfiguroinnista:

Sender address rejected: Domain not found (in reply to RCPT TO command

myorigin on määritetty väärin /etc/mailname tiedostosta. Tämän tulee olemaan domainin nimi. 

 myorigin /etc/mailname

 example.com

Client host rejected: Access denied

Relayhost on estänyt sinut, ehkä roskapostien takia.

connect to mx3.hotmail.com[65.55.37.104]:25: No route to host

Tarkista Relayhost main.cf tiedostossa. Mahdollisesti sinulla on suljettu suoraan portti 25.

Host or domain name not found. Name service error for name=gmail.con type=A: Host not found

DNS Virhe. Tarkista resolv.conf tiedostossa määriteytyt DNS asetukset. Kokeile nslookup komentoa.

Invalid mail address, must be fully qualified domain (in reply to RCPT TO command))

Isäntänimessä ongelma. Varmista että DNS on oikein määritetty ja isäntänimi main.cf tiedostossa.

unable to verify address (in reply to MAIL FROM command))

DNS ongelma. Varmista että sinulla on määritetty oikein A-records DNS palvelimelle ja MX-records. Tarkista /etc/hosts tiedosto. Korjaus: 

nano /etc/hosts

127.0.0.1       localhost mail.example.com server
127.0.1.1       example.com mail.example.com server

Lähteet

http://www.postfix.org/

https://wiki.debian.org/Postfix

http://www.sami-lehtinen.net/blog/securing-email-transport-starttls-postfix-ca-certificates-fingerprint-authority

Noudettu kohteesta ”https://taisto.org/index.php?title=Postfix/en&oldid=8078”
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