Bonjour à tous,
Depuis quelques temps, la société où je travaille subit de nombreuses et différentes attaques. Aujourd’hui, je cherche à protéger au mieux notre serveur mail (dédié) utilisant postfix, dovecot, amavis, mysql pour les users et ispconfig pour l’administration. Nos MX sont des firewalls qui analysent les mails entrants puis les envoient à notre serveur.
Depuis quelques semaines, notre serveur est passé de quelques centaines de mails sortant à environ 500000 par jour… Nous avons été blaklisté et le sommes encore chez certains destinataires.
Voici le fichier main.cf:
[code]# See /usr/share/postfix/main.cf.dist for a commented, more complete version
Debian specific: Specifying a file name will cause the first
line of that file to be used as the name. The Debian default
is /etc/mailname.
#myorigin = /etc/mailname
smtpd_banner = $myhostname ESMTP $mail_name (Debian/GNU)
biff = no
appending .domain is the MUA’s job.
append_dot_mydomain = no
Uncomment the next line to generate “delayed mail” warnings
#delay_warning_time = 4h
readme_directory = /usr/share/doc/postfix
debug_peer_list = 127.0.0.1
TLS parameters
smtpd_tls_cert_file = /etc/postfix/tls/smtpd.pem
smtpd_tls_key_file = /etc/postfix/tls/smtpd.key
smtpd_tls_CAfile = /etc/postfix/tls/smtpdI.pem
smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
myhostname = mail.notredomaine.com
mydomain = domaine.com
alias_maps = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
alias_database = hash:/etc/aliases, hash:/var/lib/mailman/data/aliases
myorigin = /etc/mailname
mydestination = localhost, localhost.localdomain
relayhost =
mynetworks = 127.0.0.0/8 [::1]/128 IP_MX1 IP_MX2 IP_MX3
relay_domains = domain1.com, domain2.com
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
html_directory = /usr/share/doc/postfix/html
virtual_alias_domains =
virtual_alias_maps = hash:/var/lib/mailman/data/virtual-mailman, proxy:mysql:/etc/postfix/mysql-virtual_forwardings.cf, proxy:mysql:/etc/postfix/mysql-virtual_email2email.cf
virtual_mailbox_domains = proxy:mysql:/etc/postfix/mysql-virtual_domains.cf
virtual_mailbox_maps = proxy:mysql:/etc/postfix/mysql-virtual_mailboxes.cf
virtual_mailbox_base = /var/vmail
virtual_uid_maps = static:5000
virtual_gid_maps = static:5000
#inet_protocols = all
inet_protocols = all
smtpd_sasl_auth_enable = yes
broken_sasl_auth_clients = yes
smtpd_sasl_authenticated_header = yes
smtpd_recipient_restrictions = permit_mynetworks, permit_sasl_authenticated, reject_unauth_destination, check_recipient_access mysql:/etc/postfix/mysql-virtual_recipient.cf, reject_rbl_client zen.spamhaus.org, reject_rbl_client zen.spamhaus.org, reject_rhsbl_helo dbl.spamhaus.org, reject_rhsbl_sender dbl.spamhaus.org
smtpd_tls_security_level = may
transport_maps = hash:/var/lib/mailman/data/transport-mailman, proxy:mysql:/etc/postfix/mysql-virtual_transports.cf
relay_domains = mysql:/etc/postfix/mysql-virtual_relaydomains.cf
relay_recipient_maps = mysql:/etc/postfix/mysql-virtual_relayrecipientmaps.cf
proxy_read_maps = $local_recipient_maps $mydestination $virtual_alias_maps $virtual_alias_domains $virtual_mailbox_maps $virtual_mailbox_domains $relay_recipient_maps $relay_domains $canonical_maps $sender_canonical_maps $recipient_canonical_maps $relocated_maps $transport_maps $mynetworks
#smtpd_sender_restrictions = check_sender_access mysql:/etc/postfix/mysql-virtual_sender.cf
smtpd_sender_restrictions = check_sender_access mysql:/etc/postfix/mysql-virtual_sender.cf
#smtpd_client_restrictions = check_client_access mysql:/etc/postfix/mysql-virtual_client.cf
smtpd_client_restrictions = check_client_access mysql:/etc/postfix/mysql-virtual_client.cf
smtpd_client_message_rate_limit = 100
maildrop_destination_concurrency_limit = 1
maildrop_destination_recipient_limit = 1
virtual_transport = dovecot
header_checks = regexp:/etc/postfix/header_checks
mime_header_checks = regexp:/etc/postfix/mime_header_checks
nested_header_checks = regexp:/etc/postfix/nested_header_checks
body_checks = regexp:/etc/postfix/body_checks
owner_request_special = no
smtp_tls_security_level = may
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3
smtpd_tls_protocols = !SSLv2,!SSLv3
smtp_tls_protocols = !SSLv2,!SSLv3
dovecot_destination_recipient_limit = 1
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
content_filter = amavis:[127.0.0.1]:10024
receive_override_options = no_address_mappings
#smtpd_tls_auth_only = yes
smtp_tls_loglevel = 1
#tls_ssl_options = NO_COMPRESSION
smtpd_tls_mandatory_ciphers = high
tls_high_cipherlist = EDH+CAMELLIA:EDH+aRSA:EECDH+aRSA+AESGCM:EECDH+aRSA+SHA384:EECDH+aRSA+SHA256:EECDH:+CAMELLIA256:+AES256:+CAMELLIA128:+AES128:+SSLv3:!aNULL:!eNULL:!LOW:!3DES:!MD5:!EXP:!PSK:!DSS:!RC4:!SEED:!ECDSA:CAMELLIA256-SHA:AES256-SHA:CAMELLIA128-SHA:AES128-SHA
smtpd_tls_mandatory_exclude_ciphers = aNULL, eNULL, EXPORT, DES, RC4, MD5, PSK, aECDH, EDH-DSS-DES-CBC3-SHA, EDH-RSA-DES-CDC3-SHA, KRB5-DE5, CBC3-SHA
#smtpd_tls_dh1024_param_file = /etc/ssl/private/dhparams.pem
message_size_limit = 0
#smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt
Don’t accept mail from domains that don’t exist.
smtpd_sender_restrictions = reject_unknown_sender_domain
Block clients that speak too early.
smtpd_data_restrictions = reject_unauth_pipelining [/code]
Notre master.cf
[code]#
Postfix master process configuration file. For details on the format
of the file, see the master(5) manual page (command: “man 5 master”).
Do not forget to execute “postfix reload” after editing this file.
==========================================================================
service type private unpriv chroot wakeup maxproc command + args
(yes) (yes) (yes) (never) (100)
==========================================================================
smtp inet n - - - - smtpd
-o smtpd_tls_security_level=none
-o smtpd_sasl_auth_enable=yes
-o smtpd_client_restrictions=permit_sasl_authenticated,permit_mynetworks,reject
#smtp inet n - - - 1 postscreen
#smtpd pass - - - - - smtpd
#dnsblog unix - - - - 0 dnsblog
#tlsproxy unix - - - - 0 tlsproxy
#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,permit_mynetworks,check_relay_domains,reject
-o milter_macro_daemon_name=ORIGINATING
#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
#628 inet n - - - - qmqpd
pickup fifo n - - 60 1 pickup
cleanup unix n - - - 0 cleanup
qmgr fifo n - n 300 1 qmgr
#qmgr fifo n - n 300 1 oqmgr
tlsmgr unix - - - 1000? 1 tlsmgr
rewrite unix - - - - - trivial-rewrite
bounce unix - - - - 0 bounce
defer unix - - - - 0 bounce
trace unix - - - - 0 bounce
verify unix - - - - 1 verify
flush unix n - - 1000? 0 flush
proxymap unix - - n - - proxymap
proxywrite unix - - n - 1 proxymap
smtp unix - - - - - smtp
relay unix - - - - - smtp
-o smtp_helo_timeout=5 -o smtp_connect_timeout=5
showq unix n - - - - showq
error unix - - - - - error
retry unix - - - - - error
discard unix - - - - - discard
local unix - n n - - local
virtual unix - n n - - virtual
lmtp unix - - - - - lmtp
anvil unix - - - - 1 anvil
scache unix - - - - 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.
Many of the following services use the Postfix pipe(8) delivery
agent. See the pipe(8) man page for information about ${recipient}
and other message envelope options.
====================================================================
maildrop. See the Postfix MAILDROP_README file for details.
Also specify in main.cf: maildrop_destination_recipient_limit=1
maildrop unix - n n - - pipe
flags=DRhu user=vmail argv=/usr/bin/maildrop -d vmail ${extension} ${recipient} ${user} ${nexthop} ${sender}
====================================================================
Recent Cyrus versions can use the existing “lmtp” master.cf entry.
Specify in cyrus.conf:
lmtp cmd=“lmtpd -a” listen=“localhost:lmtp” proto=tcp4
Specify in main.cf one or more of the following:
mailbox_transport = lmtp:inet:localhost
virtual_transport = lmtp:inet:localhost
====================================================================
Cyrus 2.1.5 (Amos Gouaux)
Also specify in main.cf: cyrus_destination_recipient_limit=1
#cyrus unix - n n - - pipe
user=cyrus argv=/cyrus/bin/deliver -e -r ${sender} -m ${extension} ${user}
====================================================================
Old example of delivery via Cyrus.
#old-cyrus unix - n n - - pipe
flags=R user=cyrus argv=/cyrus/bin/deliver -e -m ${extension} ${user}
====================================================================
See the Postfix UUCP_README file for configuration details.
uucp unix - n n - - pipe
flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
Other external delivery methods.
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=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix - n n - 2 pipe
flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} ${user} ${extension}
mailman unix - n n - - pipe
flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
${nexthop} ${user}
ispconfig 3
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 smtpd_client_restrictions=permit_sasl_authenticated
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
dovecot unix - n n - - pipe
flags=DRhu user=vmail:vmail argv=/usr/lib/dovecot/deliver -f ${sender} -d ${user}@${nexthop}
amavis unix - - - - 2 smtp
-o smtp_data_done_timeout=1200
-o smtp_send_xforward_command=yes
127.0.0.1:10025 inet n - - - - smtpd
-o content_filter=
-o local_recipient_maps=
-o relay_recipient_maps=
-o smtpd_restriction_classes=
-o smtpd_client_restrictions=
-o smtpd_helo_restrictions=
-o smtpd_sender_restrictions=
-o smtpd_recipient_restrictions=permit_mynetworks,reject
-o mynetworks=127.0.0.0/8
-o strict_rfc821_envelopes=yes
-o receive_override_options=no_unknown_recipient_checks,no_header_body_checks[/code]