Introduction
This is an advanced email server configuration. This configuration will allow you to serve multiple domains on one server. This howto will allow you to setup a server that is one of four mail server types:
- Mail server with spam and virus checking (Most people. Do everything in the howto)
- Mail server w/o spam and virus checking (Someone else is doing email filtering for you)
- Backup MX / spam and virus filtering server (you want to divide things up)
- Backup MX (You want to receive and hold mail while your main server is down)
You will get the following features:
- Postfix: the workhorse behind the mail receiving and sending
- smtp authentication
- secure smtp using TLS
- Dovecot: imap and pop3 mailbox service
- secure imap and pop3
- server side filtering of flagged spam to a spam folder
- mysql: handle all the virtual domains and users
- PostfixAdmin: GUI for domain administration
- roundcube: web mail access
- spam/virus filtering using amavisd-new, spamassassin and clamav
Books You May Find Helpful
The following books may be helpful for some people.
The Accidental Administrator: Linux Server Step-by-Step Configuration Guide
Learning the bash Shell: Unix Shell Programming (In a Nutshell (O’Reilly))
Installing CentOS
Start with my HOWTO: CentOS 6.x base server. That howto will get CentOS installed and ready for this howto.
WARNING: Not following the base server howto will cause you grief. Due to 6.4+ changes things will break.
Installing The Software
We’ll start with the yum installs.
> yum install roundcubemail dovecot dovecot-mysql dovecot-pigeonhole cyrus-sasl-devel cyrus-sasl-sql subversion
> yum install perl-MailTools perl-MIME-EncWords perl-MIME-Charset perl-Email-Valid perl-Test-Pod perl-TimeDate
> yum install perl-Mail-Sender perl-Log-Log4perl imapsync offlineimap
> yum install amavisd-new clamav clamd razor-agents perl-Convert-BinHex
Postfix.Admin doesn’t have an rpm so we need to download it and put it where we want it.
> wget http://sourceforge.net/projects/postfixadmin/files/latest/download
> tar -xzvf postfixadmin-2.3.5.tar.gz
> mv postfixadmin-2.3.5 /usr/share/postfixadmin
Configuring The Server
Setup SSL Certificate
Now generate an SSL certificate for postfix and dovecot to have TLS support. Replace mail.example.com with your server hostname.
> genkey –days 3650 mail.example.com
Setup the Virtual Mail User
Next we’ll configure the mail store directory. We put it in the /home directory to make backups and other item easy. So type the following.
> mkdir /home/vmail
> chmod 770 /home/vmail
> useradd -r -u 101 -g mail -d /home/vmail -s /sbin/nologin -c “Virtual mailbox” vmail
> chown vmail:mail /home/vmail
Configuring Postfix Admin
Create the apache config file for postfixadmin and restart apache.
/etc/httpd/conf.d/postfixadmin.conf
alias /mailadmin /usr/share/postfixadmin <Directory "/usr/share/postfixadmin"> AllowOverride AuthConfig </Directory>
> service httpd restart
Now we need to setup the mysql database for postfixadmin. We only need to create the database and user. The setup file will create the rest.
> mysql -u root -p -e “CREATE DATABASE postfix;”
> mysql -u root -p -e “CREATE USER postfix@localhost IDENTIFIED BY ‘choose_a_password’;”
> mysql -u root -p -e “GRANT ALL PRIVILEGES ON postfix . * TO postfix@localhost;”
Now its time to setup the config file. Don’t forget to set your password. Paste the following into the file.
> cd /usr/share/postfixadmin
> nano -w config.local.php
<?php
/**
* Contains configuration options that override the default config file
*/
/*****************************************************************
* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
* You have to set $CONF['configured'] = true; before the
* application will run!
* Doing this implies you have changed this file as required.
* i.e. configuring database etc; specifying setup.php password etc.
*/
$CONF['configured'] = true;
// In order to setup Postfixadmin, you MUST specify a hashed password here.
// To create the hash, visit setup.php in a browser and type a password into the field,
// on submission it will be echoed out to you as a hashed value.
$CONF['setup_password'] = 'changeme';
$CONF['postfix_admin_url'] = '/mailadmin';
$CONF['database_type'] = 'mysql';
$CONF['database_host'] = 'localhost';
$CONF['database_user'] = 'postfix';
$CONF['database_password'] = 'changeme';
$CONF['database_name'] = 'postfix';
$CONF['admin_email'] = 'postmaster@change-this-to-your.domain.tld';
$CONF['encrypt'] = 'md5crypt';
$CONF['dovecotpw'] = "/usr/sbin/dovecotpw";
$CONF['min_password_length'] = 6;
$CONF['page_size'] = '20';
$CONF['domain_path'] = 'YES';
$CONF['domain_in_mailbox'] = 'NO';
$CONF['aliases'] = '50';
$CONF['mailboxes'] = '50';
$CONF['maxquota'] = '100';
$CONF['quota'] = 'YES';
$CONF['quota_multiplier'] = '1024000';
$CONF['transport'] = 'YES';
$CONF['transport_options'] = array (
'virtual', // for virtual accounts
'local', // for system accounts
'relay' // for backup mx
);
$CONF['transport_default'] = 'virtual';
$CONF['vacation'] = 'YES';
$CONF['vacation_domain'] = 'autoreply.change-this-to-your.domain.tld';
$CONF['vacation_control'] ='YES';
$CONF['vacation_control_admin'] = 'YES';
$CONF['special_alias_control'] = 'YES';
$CONF['user_footer_link'] = "http://change-this-to-your.domain.tld/main";
$CONF['show_footer_text'] = 'YES';
$CONF['footer_text'] = 'Return to change-this-to-your.domain.tld';
$CONF['footer_link'] = 'http://change-this-to-your.domain.tld';
$CONF['create_mailbox_subdirs']=array('Drafts','Spam','Sent','Trash');
$CONF['create_mailbox_subdirs_host']='localhost';
$CONF['create_mailbox_subdirs_prefix']='';
$CONF['used_quotas'] = 'YES';
$CONF['new_quota_table'] = 'YES';
// $CONF['create_mailbox_subdirs_hostoptions']=array('notls');
$CONF['create_mailbox_subdirs_hostoptions']=array('novalidate-cert','norsh');
//
// END OF CONFIG FILE
//
Next we need to run the setup.php script in a web browser. Enter the url in your browser. Ex.
http://yourdomain.tld/mailadmin/setup.php
If everything shows OK then create the admin user using the form displayed. Follow the instructions for setting the setup password.
Log into the web interface and follow the directions.
http://yourdomain.tld/mailadmin/
Configuring Postfix
Here we go with more config files. You’ll have to be sure to change some settings to match your host. The config files will have sections commented out. Don’t worry about it. These sections are for spam/virus/sympa configuration. Just copy and past to create the config files. What ever you see here replaces what already exists.
The main postfix config files.
/etc/postfix/main.cf
# postfix config file # uncomment for debugging if needed #soft_bounce=yes # postfix main mail_owner = postfix setgid_group = postdrop delay_warning_time = 4 # postfix paths html_directory = no command_directory = /usr/sbin daemon_directory = /usr/libexec/postfix queue_directory = /var/spool/postfix sendmail_path = /usr/sbin/sendmail.postfix newaliases_path = /usr/bin/newaliases.postfix mailq_path = /usr/bin/mailq.postfix manpage_directory = /usr/share/man # network settings inet_interfaces = all mydomain = yourdomain.com myhostname = host.yourdomain.com mynetworks = $config_directory/mynetworks mydestination = $myhostname, localhost.$mydomain, localhost relay_domains = proxy:mysql:/etc/postfix/mysql-relay_domains_maps.cf # mail delivery recipient_delimiter = + # mappings alias_maps = hash:/etc/aliases alias_database = hash:/etc/aliases transport_maps = hash:/etc/postfix/transport #local_recipient_maps = # virtual setup virtual_alias_maps = proxy:mysql:/etc/postfix/mysql-virtual_alias_maps.cf, regexp:/etc/postfix/virtual_regexp virtual_mailbox_base = /home/vmail virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains_maps.cf virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailbox_maps.cf virtual_mailbox_limit_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailbox_limit_maps.cf virtual_minimum_uid = 101 virtual_uid_maps = static:101 virtual_gid_maps = static:12 virtual_transport = dovecot dovecot_destination_recipient_limit = 1 # debugging debug_peer_level = 2 debugger_command = PATH=/bin:/usr/bin:/usr/local/bin:/usr/X11R6/bin xxgdb $daemon_directory/$process_name $process_id & sleep 5 # authentication smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous smtpd_sasl_local_domain = $myhostname broken_sasl_auth_clients = yes smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth # tls config smtp_use_tls = yes smtpd_use_tls = yes smtpd_tls_security_level = may smtpd_tls_loglevel = 1 smtpd_tls_received_header = yes smtpd_tls_session_cache_timeout = 3600s tls_random_source = dev:/dev/urandom smtp_tls_session_cache_database = btree:$data_directory/smtp_tls_session_cache # Change mail.example.com.* to your host name smtpd_tls_key_file = /etc/pki/tls/private/mail.example.com.key smtpd_tls_cert_file = /etc/pki/tls/certs/mail.example.com.crt # smtpd_tls_CAfile = /etc/pki/tls/root.crt # rules restrictions smtpd_client_restrictions = smtpd_helo_restrictions = smtpd_sender_restrictions = smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, reject_non_fqdn_sender, reject_non_fqdn_recipient, reject_unknown_recipient_domain # uncomment for realtime black list checks # ,reject_rbl_client zen.spamhaus.org # ,reject_rbl_client bl.spamcop.net # ,reject_rbl_client dnsbl.sorbs.net smtpd_helo_required = yes unknown_local_recipient_reject_code = 550 disable_vrfy_command = yes smtpd_data_restrictions = reject_unauth_pipelining # Other options # email size limit ~20Meg message_size_limit = 204800000
/etc/postfix/master.cf
#
# Postfix master process configuration file. For details on the format
# of the file, see the Postfix master(5) manual page.
#
# ***** Unused items removed *****
# ==========================================================================
# service type private unpriv chroot wakeup maxproc command + args
# (yes) (yes) (yes) (never) (100)
# ==========================================================================
smtp inet n - n - - smtpd
# -o content_filter=smtp-amavis:127.0.0.1:10024
# -o receive_override_options=no_address_mappings
pickup fifo n - n 60 1 pickup
-o content_filter=
-o receive_override_options=no_header_body_checks
cleanup unix n - n - 0 cleanup
qmgr fifo n - n 300 1 qmgr
#qmgr fifo n - n 300 1 oqmgr
tlsmgr unix - - n 1000? 1 tlsmgr
rewrite unix - - n - - trivial-rewrite
bounce unix - - n - 0 bounce
defer unix - - n - 0 bounce
trace unix - - n - 0 bounce
verify unix - - n - 1 verify
flush unix n - n 1000? 0 flush
proxymap unix - - n - - proxymap
smtp unix - - n - - smtp
# When relaying mail as backup MX, disable fallback_relay to avoid MX loops
relay unix - - n - - smtp
-o fallback_relay=
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - n - - showq
error unix - - n - - error
discard unix - - n - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - n - - lmtp
anvil unix - - n - 1 anvil
scache unix - - n - 1 scache
#
# ====================================================================
# Interfaces to non-Postfix software. Be sure to examine the manual
# pages of the non-Postfix software to find out what options it wants.
# ====================================================================
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/local/bin/maildrop -d ${recipient}
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
ifmail unix - n n - - pipe
flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp unix - n n - - pipe
flags=Fq. user=foo argv=/usr/local/sbin/bsmtp -f $sender $nexthop $recipient
#
# spam/virus section
#
smtp-amavis unix - - y - 2 smtp
-o smtp_data_done_timeout=1200
-o disable_dns_lookups=yes
-o smtp_send_xforward_command=yes
127.0.0.1:10025 inet n - y - - smtpd
-o content_filter=
-o smtpd_helo_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,reject
-o mynetworks=127.0.0.0/8
-o smtpd_error_sleep_time=0
-o smtpd_soft_error_limit=1001
-o smtpd_hard_error_limit=1000
-o receive_override_options=no_header_body_checks
-o smtpd_bind_address=127.0.0.1
-o smtpd_helo_required=no
-o smtpd_client_restrictions=
-o smtpd_restriction_classes=
-o disable_vrfy_command=no
-o strict_rfc821_envelopes=yes
#
# Dovecot LDA
dovecot unix - n n - - pipe
flags=DRhu user=vmail:mail argv=/usr/libexec/dovecot/deliver -d ${recipient}
#
# Vacation mail
vacation unix - n n - - pipe
flags=Rq user=vacation argv=/var/spool/vacation/vacation.pl -f ${sender} -- ${recipient}
/etc/postfix/mynetworks
# This specifies the list of subnets that Postfix considers as # "trusted" SMTP clients that have more privileges than "strangers". # # In particular, "trusted" SMTP clients are allowed to relay mail # through Postfix. # # Be sure to add your public ip address block if needed. # 192.168.0.0/16 10.0.0.0/8 127.0.0.0/8
The postfix / mysql config files.
/etc/postfix/mysql-virtual_alias_maps.cf
hosts = localhost user = postfix password = postfix dbname = postfix query = SELECT goto FROM alias WHERE address='%s' AND active = '1'
/etc/postfix/mysql-virtual_domains_maps.cf
hosts = localhost user = postfix password = postfix dbname = postfix query = SELECT domain FROM domain WHERE domain='%s' AND backupmx = '0' AND active = '1'
/etc/postfix/mysql-relay_domains_maps.cf
hosts = localhost user = postfix password = postfix dbname = postfix query = SELECT domain FROM domain WHERE domain='%s' and backupmx = '1'
/etc/postfix/mysql-virtual_mailbox_maps.cf
hosts = localhost user = postfix password = postfix dbname = postfix query = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'
/etc/postfix/mysql-virtual_mailbox_limit_maps.cf
hosts = localhost user = postfix password = postfix dbname = postfix query = SELECT quota FROM mailbox WHERE username='%s' AND active = '1'
We need to touch a file. So type the follwoing.
> touch /etc/postfix/virtual_regexp
Configure Vacation Email Functionallity
Lets finish the postfix configuration with vacation mail. Don’t forget to fill in your domain name where needed. Type the following:
> useradd -r -d /var/spool/vacation -s /sbin/nologin -c “Virtual vacation” vacation
> mkdir /var/spool/vacation
> chmod 770 /var/spool/vacation
> cp /usr/share/postfixadmin/VIRTUAL_VACATION/vacation.pl /var/spool/vacation/
> echo “autoreply.yourdomain.com vacation:” > /etc/postfix/transport
> postmap /etc/postfix/transport
> chown -R vacation:vacation /var/spool/vacation
> echo “127.0.0.1 autoreply.yourdomain.com” >> /etc/hosts
> mkdir /etc/postfixadmin
Create /etc/postfixadmin/vacation.conf with the following:
# ========== begin configuration ========== $db_type = 'mysql'; $db_username = 'user'; $db_password = 'password'; $db_name = 'postfix'; $vacation_domain = 'autoreply.example.org';
Configuring Dovecot
Now for the dovecot config file. Dovecot now uses multiple config files to break things up. We’re going to only use a couple config files. So cut and paste the following files.
> mv /etc/dovecot/dovecot.conf /etc/dovecot/dovecot.conf.save
> nano -w /etc/dovecot/dovecot.conf
##
## Dovecot config file
##
protocols = imap pop3 lmtp sieve
auth_mechanisms = plain login
passdb {
driver = sql
args = /etc/dovecot/dovecot-mysql.conf
}
userdb {
driver = prefetch
}
userdb {
driver = sql
args = /etc/dovecot/dovecot-mysql.conf
}
mail_location = maildir:/home/vmail/%d/%n
first_valid_uid = 101
#last_valid_uid = 0
first_valid_gid = 12
#last_valid_gid = 0
#mail_plugins =
mailbox_idle_check_interval = 30 secs
maildir_copy_with_hardlinks = yes
service imap-login {
inet_listener imap {
port = 143
}
inet_listener imaps {
port = 993
ssl = yes
}
}
service pop3-login {
inet_listener pop3 {
port = 110
}
inet_listener pop3s {
port = 995
ssl = yes
}
}
service lmtp {
unix_listener lmtp {
#mode = 0666
}
}
service imap {
vsz_limit = 256M
}
service pop3 {
}
service auth {
unix_listener auth-userdb {
mode = 0666
user = vmail
group = mail
}
# Postfix smtp-auth
unix_listener /var/spool/postfix/private/auth {
mode = 0666
user = postfix
group = postfix
}
}
service auth-worker {
}
service dict {
unix_listener dict {
mode = 0666
user = vmail
group = mail
}
}
service managesieve-login {
inet_listener sieve {
port = 4190
}
service_count = 1
process_min_avail = 0
vsz_limit = 64M
}
service managesieve {
}
ssl = yes
ssl_cert = </etc/pki/tls/certs/your-server.your-domain.tld.crt
ssl_key = </etc/pki/tls/private/your-server.your-domain.tld.key
ssl_verify_client_cert = no
#ssl_ca =
lda_mailbox_autocreate = yes
lda_mailbox_autosubscribe = yes
protocol lda {
mail_plugins = quota sieve
postmaster_address = postmaster@your-domain.tld
}
protocol imap {
mail_plugins = quota imap_quota trash
imap_client_workarounds = delay-newmail
}
lmtp_save_to_detail_mailbox = yes
protocol lmtp {
mail_plugins = sieve
}
protocol pop3 {
mail_plugins = quota
pop3_client_workarounds = outlook-no-nuls oe-ns-eoh
}
protocol sieve {
managesieve_max_line_length = 65536
managesieve_implementation_string = Dovecot Pigeonhole
managesieve_max_compile_errors = 5
}
dict {
quotadict = mysql:/etc/dovecot/dovecot-dict-quota.conf
}
plugin {
quota = dict:user::proxy::quotadict
acl = vfile:/etc/dovecot/acls
trash = /etc/dovecot/trash.conf
sieve_global_path = /home/sieve/globalfilter.sieve
sieve = ~/dovecot.sieve
sieve_dir = ~/sieve
sieve_global_dir = /home/sieve/
#sieve_extensions = +notify +imapflags
sieve_max_script_size = 1M
#sieve_max_actions = 32
#sieve_max_redirects = 4
}
Now for trash.conf
> nano -w /etc/dovecot/trash.conf
1 Spam # Uncomment if you want trash as well # 2 Trash
Next we configure Dovecot to access mysql. Create the following file.
NOTE: password_query and user_query were formatted to fit on the webpage. Each one should only be one line in the file.
/etc/dovecot/dovecot-mysql.conf
driver = mysql
connect = host=localhost dbname=postfix user=postfix password=yourpassword
default_pass_scheme = MD5-CRYPT
# following should all be on one line.
password_query = SELECT username as user, password, concat('/home/vmail/', maildir) as userdb_home,
concat('maildir:/home/vmail/', maildir) as userdb_mail, 101 as userdb_uid, 12 as userdb_gid FROM mailbox
WHERE username = '%u' AND active = '1'
# following should all be on one line
user_query = SELECT concat('/home/vmail/', maildir) as home, concat('maildir:/home/vmail/', maildir) as mail,
101 AS uid, 12 AS gid, CONCAT('*:messages=10000:bytes=', quota) as quota_rule FROM mailbox WHERE
username = '%u' AND active = '1'
and /etc/dovecot/dovecot-dict-quota.conf
connect = host=localhost dbname=postfix user=postfix password=password
map {
pattern = priv/quota/storage
table = quota2
username_field = username
value_field = bytes
}
map {
pattern = priv/quota/messages
table = quota2
username_field = username
value_field = messages
}
Finally set Dovecot to boot at startup.
Now Create the sieve filter for SPAM filtering.
> mkdir /home/sieve
> nano -w /home/sieve/globalfilter.sieve
> chown -R vmail:mail /home/sieve
require "fileinto";
if exists "X-Spam-Flag" {
if header :contains "X-Spam-Flag" "NO" {
} else {
fileinto "Spam";
stop;
}
}
if header :contains "subject" ["***SPAM***"] {
fileinto "Spam";
stop;
}
Configuring Roundcube mail
Edit the roundcube apache config file to look like the following:
>nano -w /etc/httpd/conf.d/roundcubemail.conf
#
# Round Cube Webmail is a browser-based multilingual IMAP client
#
# Force https here instead of in Round Cube
RewriteEngine On
# This checks to make sure the connection is not already HTTPS
RewriteCond %{HTTPS} !=on
# These rules will redirect all users who are using any part of /secure/ to the same location but using HTTPS.
# i.e. http://www.example.com/secure/ to https://www.example.com/secure/
RewriteRule ^/?roundcubemail/(.*) https://%{SERVER_NAME}/roundcubemail/$1 [R,L]
RewriteRule ^/?webmail/(.*) https://%{SERVER_NAME}/webmail/$1 [R,L]
Alias /roundcubemail /usr/share/roundcubemail
Alias /webmail /usr/share/roundcubemail
<Directory /usr/share/roundcubemail/>
Order Deny,Allow
Deny from all
Allow from all
php_value suhosin.session.encrypt Off
</Directory>
Create the database for roundcube.
> mysql -u root -p -e “CREATE DATABASE roundcubemail;”
> mysql -u root -p -e “GRANT ALL PRIVILEGES ON roundcubemail.* TO roundcube@localhost IDENTIFIED BY ‘password’;”
Create the tables.
> mysql -u root -p roundcubemail < /usr/share/doc/roundcubemail-0.5.4/SQL/mysql.initial.sql
Edit /etc/roundcubemail/db.inc.php and find the line:
$rcmail_config['db_dsnw'] = 'mysql://roundcube:pass@localhost/roundcubemail';
Change ‘pass’ to your passowrd.
Edit /etc/roundcubemail/main.inc.php and find the lines and make the changes below:
find:
$rcmail_config['default_host'] = '';
change to:
$rcmail_config['default_host'] = 'localhost';
find:
$rcmail_config['smtp_server'] = '';
change to:
$rcmail_config['smtp_server'] = 'localhost';
find:
$rcmail_config['force_https'] = false;
change to:
$rcmail_config['force_https'] = true;
find:
$rcmail_config['plugins'] = array();
change to:
$rcmail_config['plugins'] = array('managesieve');
find:
$rcmail_config['quota_zero_as_unlimited'] = false;
change to:
$rcmail_config['quota_zero_as_unlimited'] = true;
Now lets configure the manage sieve plugin.
> cd /usr/share/roundcubemail/plugins/managesieve/
> cp config.inc.php.dist config.inc.php
Edit config.inc.php and change the following:
$rcmail_config['managesieve_port'] = 2000;
to:
$rcmail_config['managesieve_port'] = 4190;
Restart apache.
> service httpd restart
Configuring the Little Things That Drive You MAD
Be sure your /etc/hosts looks similar to the following.
# Do not remove the following line, or various programs # that require network functionality will fail. 127.0.0.1 localhost 192.168.11.21 host.domain.com
Preparing and Testing the Postoffice
First things first. Reboot the system. If everything went well we all should be at the same point.
No errors? Lets keep going.
Setup a test domain and account. Setup your favorit mail client and send some test emails.
Setting up Spam and Virus Filtering (Optional)
Lets cover installing and configuring spam and virus filtering. Optional? Huh? Some people use a 3rd party or use a seperate server for filtering.
Here’s the clamav config file. Replace /etc/clamd.conf with the following:
## ## Cconfig file for the Clam AV daemon ## Please read the clamd.conf(5) manual before editing this file. ## # Logfile LogFile /var/log/clamav/clamd.log LogFileMaxSize 20M LogTime yes LogSyslog yes # Pid PidFile /var/run/clamav/clamd.pid # Paths TemporaryDirectory /var/tmp DatabaseDirectory /var/clamav LocalSocket /var/run/clamav/clamd # Sets the group ownership on the unix socket. # Default: disabled (the primary group of the user running clamd) #LocalSocketGroup virusgroup # Misc FixStaleSocket yes TCPSocket 3310 TCPAddr 127.0.0.1 MaxConnectionQueueLength 50 MaxThreads 50 ReadTimeout 240 User clamav AllowSupplementaryGroups yes # Exe ScanPE yes ScanELF yes DetectBrokenExecutables yes # Docs ScanOLE2 yes ScanPDF yes # Mail ScanMail yes PhishingSignatures yes PhishingScanURLs yes # Data Loss Prevention (DLP) # Enable the DLP module # Default: No #StructuredDataDetection yes # This option sets the lowest number of Credit Card numbers found in a file # to generate a detect. # Default: 3 #StructuredMinCreditCardCount 5 # This option sets the lowest number of Social Security Numbers found # in a file to generate a detect. # Default: 3 #StructuredMinSSNCount 5 # With this option enabled the DLP module will search for valid # SSNs formatted as xxx-yy-zzzz # Default: yes #StructuredSSNFormatNormal yes # With this option enabled the DLP module will search for valid # SSNs formatted as xxxyyzzzz # Default: no #StructuredSSNFormatStripped yes # Archives ScanArchive yes ArchiveBlockEncrypted no
Configure Razor. Type the following:
> razor-admin -register -user=some_user -pass=somepas
Update and restart clamav:
> freshclam
> service clamd restart
Configuring Amavisd-new
You need to edit /etc/amavisd.conf
Here is a list of items you should change. just scroll through the file to find each item.
- $mydomain = ‘example.com’; # set to your domain name
- $log_level = 1; # set the log leve to one
- $sa_tag_level_deflt = -99; # i want to see the headers so change to -99
- $sa_tag2_level_deflt = 5.0; # start with 5
- $sa_kill_level_deflt = 9; # change to 9
- $sa_dsn_cutoff_level = 9; # change to 9
- $sa_quarantine_cutoff_level = 50; # remove the starting # and change to 50
- $myhostname = ‘lightning.campworld.net’; # remove the starting # and enter your host name
- $notify_method = ‘smtp:[127.0.0.1]:10025’; # uncomment the line
- $forward_method = ‘smtp:[127.0.0.1]:10025’; # uncomment the line
- $final_banned_destiny = D_DISCARD; # change to D_DISCARD
Now enable clamav:
Change the following:
# ### http://www.clamav.net/
# ['ClamAV-clamd',
# \&ask_daemon, ["CONTSCAN {}\n", "/var/run/clamav/clamd"],
# qr/\bOK$/m, qr/\bFOUND$/m,
# qr/^.*?: (?!Infected Archive)(.*) FOUND$/m ],
to
### http://www.clamav.net/
['ClamAV-clamd',
\&ask_daemon, ["CONTSCAN {}\n", "/var/run/clamav/clamd"],
qr/\bOK$/m, qr/\bFOUND$/m,
qr/^.*?: (?!Infected Archive)(.*) FOUND$/m ],
Now update spamassassin and start amavisd-new.
> sa-update
> service amavisd-new start
Be sure to set amavisd-new to start at boot.
Telling Postfix to Start Filtering SPAM
To get postfix going we need to un-comment a couple lines in /etc/postfix/master.cf
Find:
smtp inet n - n - - smtpd # -o content_filter=smtp-amavis:127.0.0.1:10024 # -o receive_override_options=no_address_mappings
Change to:
smtp inet n - n - - smtpd -o content_filter=smtp-amavis:127.0.0.1:10024 -o receive_override_options=no_address_mappings
Restart postfix and you’re done.
Using The Roundcubemail Password Plugin (Optional)
Let your users change their password using roundcubemail instead of postfixadmin.
Edit /etc/roundcubemail/main.inc.php and find the lines and make the changes below:
find:
$rcmail_config['plugins'] = array('managesieve');
change to:
$rcmail_config['plugins'] = array('managesieve','password');
Now lets configure the password plugin.
> cd /usr/share/roundcubemail/plugins/password/
> cp config.inc.php.dist config.inc.php
Edit config.inc.php
find:
$rcmail_config['password_db_dsn'] = '';
change to:
$rcmail_config['password_db_dsn'] = 'mysql://postfix:your-postfixadmin-password@localhost/postfix';
find:
$rcmail_config['password_query'] = 'SELECT update_passwd(%c, %u)';
change to:
$rcmail_config['password_query'] = 'UPDATE mailbox SET password=%c WHERE username=%u limit 1;';
Restart apache.
> service httpd restart
What is OpenDKIM?
It is a digital email signing/verification technology, which is already supported by some common mail providers. In general, DKIM means digitally signing all messages on the mail-server to verify the message was actually sent from the domain in question and was not spam
INSTALL OPENDKIM
Install the package using yum:
## yum install opendkim
CONFIGURE OPENDKIM
Next thing to do is to configure OpenDKIM. Its main configuration file is located in /etc/opendkim.conf, so before making any changes create a backup and add/edit the following:
## cp /etc/opendkim.conf{,.orig}
## vim /etc/opendkim.conf
AutoRestart Yes AutoRestartRate 10/1h LogWhy Yes Syslog Yes SyslogSuccess Yes Mode sv Canonicalization relaxed/simple ExternalIgnoreList refile:/etc/opendkim/TrustedHosts InternalHosts refile:/etc/opendkim/TrustedHosts KeyTable refile:/etc/opendkim/KeyTable SigningTable refile:/etc/opendkim/SigningTable SignatureAlgorithm rsa-sha256 Socket inet:8891@localhost PidFile /var/run/opendkim/opendkim.pid UMask 022 UserID opendkim:opendkim TemporaryDirectory /var/tmp
SET-UP PUBLIC/PRIVATE KEYS
Generate set of keys for your mydomain.com domain name:
## mkdir /etc/opendkim/keys/mydomain.com ## opendkim-genkey -D /etc/opendkim/keys/mydomain.com/ -d mydomain.com -s default ## chown -R opendkim: /etc/opendkim/keys/mydomain.com ## mv /etc/opendkim/keys/mydomain.com/default.private /etc/opendkim/keys/mydomain.com/default
add mydomain.com to OpenDKIM’s key table by adding the following record in /etc/opendkim/KeyTable
default._domainkey.mydomain.com mydomain.com:default:/etc/opendkim/keys/mydomain.com/default
next, edit /etc/opendkim/SigningTable and add the following record to OpenDKIM’s signing table:
*@mydomain.com default._domainkey.mydomain.com
and add your domain and your hostname as trusted hosts in /etc/opendkim/TrustedHosts:
127.0.0.1 mydomain.com host.mydomain.com
assuming the domain in question is ‘mydomain.com’ and server’s hostname is set to ‘host.mydomain.com’
finally, edit your mydomain.com DNS zone and add the TXT record from /etc/opendkim/keys/mydomain.com/default.txt
default._domainkey IN TXT ( "v=DKIM1; k=rsa; "
"p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDApHRr7ZmXRaAB+RQRbP4VdMwIrIHIP18KFtXRsv/xpWc0Gix6ZXN13fcG03KNGKZo2PY+csPkGC5quDnH5V0JEhDZ78KcDWFsU6u4fr9ktVAdt6P7jWXjcyqdHOZ8+YN4cAeU4lRFNgQvdupIcByYwzPYMgBFHfJm9014HvRqhwIDAQAB" ) ; ----- DKIM key default for mydomain.com
it is also a good idea to add an SPF record if you haven’t already
mydomain.com. 14400 IN TXT "v=spf1 a mx ~all"
you can verify your dkim TXT record is valid using dig for example:
## dig +short default._domainkey.mydomain.com TXT "v=DKIM1\; k=rsa\; " "p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDApHRr7ZmXRaAB+RQRbP4VdMwIrIHIP18KFtXRsv/xpWc0Gix6ZXN13fcG03KNGKZo2PY+csPkGC5quDnH5V0JEhDZ78KcDWFsU6u4fr9ktVAdt6P7jWXjcyqdHOZ8+YN4cAeU4lRFNgQvdupIcByYwzPYMgBFHfJm9014HvRqhwIDAQAB"
CONFIGURE POSTFIX
In order to integrate OpenDKIM with Postfix we need to add the following few lines in /etc/postfix/main.cf:
smtpd_milters = inet:127.0.0.1:8891 non_smtpd_milters = $smtpd_milters milter_default_action = accept milter_protocol = 2
(RE)START SERVICES
Add OpenDKIM to your system’s start-up and start opendkim and restart postfix using the following commands:
## service opendkim start ## chkconfig opendkim on ## service postfix restart
TEST THE SET-UP
To test the set-up simply send an email to check-auth@verifier.port25.com and you should receive back an email containing something like this:
========================================================== Summary of Results ========================================================== SPF check: pass DomainKeys check: neutral DKIM check: pass DKIM check: pass
Notes About Security And Clear Text Passwords From Mail Clients
My howto has been written to allow clear text passwords. This can and does cause security problem of sending of clear text passwords through the internet. This covers sending of the password from the client to the server. Passwords are stored in the database encrypted.
The configuration doesn’t require clients to use SSL/TLS. If you use SSL/TLS then the passwords are encrypted in the SSL connection. POPS, IMAPS and SMTPS all use SSL/TLS connection. So as long as your client supports secure connections to the mail server your clear text passwords will be secure.
Conclusion
With a bit of work you come out with a robust server.