构建反病毒反垃圾邮件系统(六)






  安装四个下载的软件包:


  # dpkg -i *.deb


  修改/etc/amavis/amavisd.conf:


  @inet_acl = qw( 127/8 1.2.3.4/32 ); # 1.2.3.4 is your external ip .. because want maybe also accept mail from that interface, it’s up to you.
  $warnvirussender = 1; # I want to warn people, who have got virus.
  $warnvirusrecip = 1; # I want to warn my users about virus send to them.
  $warn_offsite = 1; # I want to warn senders/recipients, that are not located on my server
  $mailfrom_notify_admin = ‘virusalert@example.com’; #
  $mailfrom_notify_recip = ‘virusalert@example.com’; # Change these to the appropriate email-adresses, you wish to use as sender
  $mailfrom_notify_spamadmin = ‘spam.police@example.com’; # for spam and virus warnings
  $hdrfrom_notify_sender = ‘AMaViS (content filter) <postmaster@example.com>’;
  $virus_admin = ‘virus-admin@example.com’; #
  $spam_admin = ‘spam-admin@example.com’; #


  指定使用uvscan:


  @av_scanners = (


  [‘NAI McAfee AntiVirus (uvscan)’, ‘uvscan’,
  ’–secure -rv –summary –noboot {}’, [0], [13],
  qr/(?x) Found (?:
  \ the\ (.+)\ (?:virus|trojan) |
  \ (?:virus|trojan)\ or\ variant\ ([^ ]+) |
  :\ (.+)\ NOT\ a\ virus)/ ],


  );


  找到/etc/postfix/master.cf如下行:


  smtp inet n – n – – smtpd


  改为如下:


  smtp inet n n n – – smtpd -o content_filter=smtp-amavis:[127.0.0.1]:10024
  smtp-amavis unix – – n – 2 smtp
  -o smtp_data_done_timeout=1200
  -o disable_dns_lookups=yes
  127.0.0.1:10025 inet n – n – – smtpd
  -o local_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 strict_rfc821_envelopes=yes


  重启postfix,这样在收到病毒邮件的时候能够在日志文件看到如下的信息:


  Jul 16 15:34:22 xxx amavis[30997]: (30997-09) INFECTED (W32/Nimda.gen@MM), (?) -> <xxx@xxx.org>, quarantine virus-20030716-153422-30997-09, Message-ID: <20030716073414.520D3E5C2F@xxx>


  三、防垃圾邮件部分


  垃圾邮件的防范必须掌握好尺度,postfix本身提供了header_check、body_check、access、classes等方式来拒绝邮件,可以参考如下地址的样例,结合自己的情况进行修改也能阻止一部分垃圾邮件:


  http://www.XXXX.com/guides/postfix_uce_header.html
  http://www.XXXX.com/guides/postfix_uce_body.html
  http://www.XXXX.com/guides/postfix_uce_access.html
  http://www.XXXX.com/guides/postfix_uce_class.html


  不过以上配置文件需要管理员根据自己情况手工进行修改,如果直接采用的话,那么国内很多邮件你将收不到。

  SpamAssassin和AMaViS可以很好的结合,它能够帮管理员自动处理一些垃圾邮件。SpamAssassin很有趣,它对解码后的邮件进行扫描后打分,如果分数达到用户指定的分数,那么就认为是垃圾邮件,而且它还有学习功能,管理员也可以自己重新定义各种分值或自定义分值。


  1、SpamAssassin的安装


  由于已经安装了AMaViS,所以自然就选择了SpamAssassin。SpamAssassin可以通过CPAN安装:


  # perl -MCPAN -e shell
  install Mail::SpamAssassin


  2、SpamAssassin配置


  创建/var/lib/amavis/.spamassassin/user_prefs文件:


  # SpamAssassin config file for version 2.5x
  # generated by http://www.yrex.com/spam/spamconfig.php (version 1.01)


  # How many hits before a message is considered spam.
  required_hits 5.0


  # Whether to change the subject of suspected spam
  rewrite_subject 1


  # Text to prepend to subject if rewrite_subject is used
  subject_tag *****SPAM*****


  # Encapsulate spam in an attachment
  report_safe 1


  # Use terse version of the spam report
  use_terse_report 0


  # Enable the Bayes system
  use_bayes 1


  # Enable Bayes auto-learning
  auto_learn 1


  # Enable or disable network checks
  skip_rbl_checks 1
  use_razor2 0
  use_dcc 0
  use_pyzor 0


  # Mail using languages used in these country codes will not be marked
  # as being possibly spam in a foreign language.
  # – chinese english
  ok_languages zh en


  # Mail using locales used in these country codes will not be marked
  # as being possibly spam in a foreign language.
  ok_locales en zh