Contents
Install clamav ( anti-virus software )
1.Clam AntiVirus Install
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# dnf -y install clamav clamd clamav-update |
2.Clam AntiVirus Configuration File Editing
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# vi /etc/clamd.d/scan.conf ●Line 14 # Default: disabled LogFile /var/log/clamd.scan ← Uncomment ●Line 77 # Default: disabled PidFile /run/clamd.scan/clamd.pid ← Uncomment ●Line 96 # Path to a local socket file the daemon will listen on. # Default: disabled (must be specified by a user) LocalSocket /run/clamd.scan/clamd.sock ← Uncomment ●Line 219 # Run as another user (clamd must be started by root for this option to work) # Default: don't drop privileges #User clamscan ← Add # at the beginning of the line and comment it out (to make it work with root privileges) |
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# vi /etc/freshclam.conf ●Line 75 Insert a "#" at the beginning of the line "DatabaseMirror database.clamav.net" and Add "DatabaseMirror db.jp.clamav.net" #DatabaseMirror database.clamav.net DatabaseMirror db.jp.clamav.net ●Per line 151 Add "NotifyClamd /etc/clamd.d/scan.conf #NotifyClamd /path/to/clamd.conf NotifyClamd /etc/clamd.d/scan.conf |
4.Virus definition file update
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# freshclam ClamAV update process started at Wed Jun 8 17:09:20 2022 daily database available for download (remote version: 26565) Time: 3.0s, ETA: 0.0s [========================>] 56.03MiB/56.03MiB Testing database: '/var/lib/clamav/tmp.aca2d3f1fa/clamav-23517084062dbf640a1e7db5635d12b5.tmp-daily.cvd' ... Database test passed. daily.cvd updated (version: 26566, sigs: 1985565, f-level: 90, builder: raynman) main database available for download (remote version: 62) Time: 7.9s, ETA: 0.0s [========================>] 162.58MiB/162.58MiB Testing database: '/var/lib/clamav/tmp.aca2d3f1fa/clamav-31ab0225aac64a6d935b73fa24c3b497.tmp-main.cvd' ... Database test passed. main.cvd updated (version: 62, sigs: 6647427, f-level: 90, builder: sigmgr) bytecode database available for download (remote version: 333) Time: 0.5s, ETA: 0.0s [========================>] 286.79KiB/286.79KiB Testing database: '/var/lib/clamav/tmp.aca2d3f1fa/clamav-20ea46288aefc5e6fb938184abb83e92.tmp-bytecode.cvd' ... Database test passed. bytecode.cvd updated (version: 333, sigs: 92, f-level: 63, builder: awillia2) |
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# systemctl start clamd@scan ← clamd start # systemctl enable clamd@scan ← automatic clamd startup configuration Created symlink /etc/systemd/system/multi-user.target.wants/clamd@scan.service → /usr/lib/systemd/system/clamd@.service. # systemctl is-enabled clamd@scan enabled # systemctl status clamd@scan ← operation check ● clamd@scan.service - clamd scanner (scan) daemon Loaded: loaded (/usr/lib/systemd/system/clamd@.service; enabled; vendor pres> Active: active (running) since Fri 2022-07-15 19:55:41 JST; 19s ago Docs: man:clamd(8) man:clamd.conf(5) https://www.clamav.net/documents/ Main PID: 4230 (clamd) Tasks: 2 (limit: 11187) Memory: 1.2G CGroup: /system.slice/system-clamd.slice/clamd@scan.service mq4230 /usr/sbin/clamd -c /etc/clamd.d/scan.confJul 15 19:55:41 Alma clamd[4230]: ELF support enabled. Jul 15 19:55:41 Alma clamd[4230]: Mail files support enabled. Jul 15 19:55:41 Alma clamd[4230]: OLE2 support enabled. Jul 15 19:55:41 Alma clamd[4230]: PDF support enabled. Jul 15 19:55:41 Alma clamd[4230]: SWF support enabled. Jul 15 19:55:41 Alma clamd[4230]: HTML support enabled. Jul 15 19:55:41 Alma clamd[4230]: XMLDOCS support enabled. Jul 15 19:55:41 Alma clamd[4230]: HWP3 support enabled. |
6.Conduct virus scan
■Download a test virus and perform a virus scan
■Download a test virus and perform a virus scan
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# wget http://www.eicar.org/download/eicar.com # clamscan --infected --remove --recursive /root/eicar.com: Win.Test.EICAR_HDB-1 FOUND /root/eicar.com: Removed. ----------- SCAN SUMMARY ----------- Known viruses: 8622184 Engine version: 0.103.6 Scanned directories: 1 Scanned files: 10 Infected files: 1 Data scanned: 0.02 MB Data read: 0.01 MB (ratio 2.00:1) Time: 35.277 sec (0 m 35 s) Start Date: 2022:07:15 19:57:42 End Date: 2022:07:15 19:58:17 |
7.Deployment of virus scan auto-execution scripts
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# mkdir -p /var/www/system # cd /var/www/system Create clamscan.sh in /var/www/system with the following contents # vi /var/www/system/clamscan.sh #!/bin/bash PATH=/usr/bin:/bin # excludeopt setup excludelist=/var/www/system/clamscan.exclude if [ -s $excludelist ]; then for i in `cat $excludelist` do if [ $(echo "$i"|grep \/$) ]; then i=`echo $i|sed -e 's/^\([^ ]*\)\/$/\1/p' -e d` excludeopt="${excludeopt} --exclude-dir=$i" else excludeopt="${excludeopt} --exclude=$i" fi done fi # signature update freshclam # virus scan clamscan --recursive --remove ${excludeopt} / |
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# chmod 700 clamscan.sh # echo "/sys/" >> /var/www/system/clamscan.exclude # echo "/proc/" >> /var/www/system/clamscan.exclude Exclude sys and proc directories. |
9.Scheduled virus scan execution
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# crontab -e 0 1 * * * /var/www/system/clamscan.sh > /dev/null 2>&1 |
Mail Server Installation
1.Postfix Installation
1.1 Install
Install Postfix and build an SMTP server
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# dnf -y install postfix |
Make sure Postfix is installed
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# rpm -qa | grep postfix pcp-pmda-postfix-5.3.5-8.el8.x86_64 postfix-3.5.8-4.el8.x86_64 postfix-perl-scripts-3.5.8-4.el8.x86_64 |
1.2 Register Postfix to the service
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# systemctl enable postfix.service Created symlink /etc/systemd/system/multi-user.target.wants/postfix.service → /usr/lib/systemd/system/postfix.service. # systemctl is-enabled postfix.service enabled |
1.3 Backup postfix configuration files, main.cf and master.cf files
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# cp -p /etc/postfix/main.cf `date '+/etc/postfix/main.cf.%Y%m%d'` # cp -p /etc/postfix/master.cf `date '+/etc/postfix/master.cf.%Y%m%d'` |
1.4 Edit postfix configuration file
To prevent unauthorized mail relay, configure Postfix to require authentication even for outgoing mail, using Dovecot's SASL function.
To prevent unauthorized mail relay, configure Postfix to require authentication even for outgoing mail, using Dovecot's SASL function.
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# vi /etc/postfix/main.cf ●Added around line 96 #myhostname = virtual.domain.tld myhostname = mail.<Domain name> ●Add your domain name around line 103 #mydomain = domain.tld mydomain = <Domain name> ●Uncomment out per line 118 myorigin = $mydomain ●Change per line 135 inet_interfaces = all ●Added around line 183 Comment out around line 183 and add to line 184. #mydestination = $myhostname, localhost.$mydomain, localhost mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain ●Added around line 287 #mynetworks = 168.100.189.0/28, 127.0.0.0/8 #mynetworks = $config_directory/mynetworks #mynetworks = hash:/etc/postfix/network_table mynetworks = 192.168.11.0/24, 127.0.0.0/8 ←192.168.11.0/24 to suit your environment ●Uncomment per line 440 Set the mail storage format. #home_mailbox = Mailbox home_mailbox = Maildir/ ●Added around line 447 #mail_spool_directory = /var/mail mail_spool_directory = /var/spool/mail ●Added around line 593 #smtpd_banner = $myhostname ESMTP $mail_name #smtpd_banner = $myhostname ESMTP $mail_name ($mail_version) smtpd_banner = $myhostname ESMTP unknown ●Add the following to the last line #Limit send/receive mail size to 10M message_size_limit = 10485760 # Limit mailbox size to 1G mailbox_size_limit = 1073741824 # SSMTP-Auth Settings smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous smtpd_sasl_local_domain = $mydomain smtpd_recipient_restrictions = permit_mynetworks, permit_auth_destination, permit_sasl_authenticated, reject |
Release SMTP port (port 25)
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# firewall-cmd --add-service=smtp --permanent success # firewall-cmd --reload success |
1.5 Start Postfix
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# systemctl restart --now postfix |
2.Dovecot Install
2.1 dovecot install
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# dnf -y install dovecot |
2.2 Edit dovecot.conf file
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# cp -p /etc/dovecot/dovecot.conf `date '+ /etc/dovecot/dovecot.conf.%Y%m%d'` # vi /etc/dovecot/dovecot.conf ●Add around line 25 # protocols = imap pop3 lmtp protocols = imap pop3 ●Line 30 : Uncomment # Remove [::] if listening for IPv4 only listen = *, :: |
2.3 Edit 10-auth.conf file
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# vi /etc/dovecot/conf.d/10-auth.conf ●Line 10 : Uncomment and change If plain text authentication is also allowed disable_plaintext_auth = no ●Line 100 : Add auth_mechanisms = plain login |
2.3 Edit 10-mail.conf file
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# vi /etc/dovecot/conf.d/10-mail.conf ●Line 31 : Add mail_location = maildir:~/Maildir |
2.4 Edit 10-master.conf file
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# vi /etc/dovecot/conf.d/10-master.conf ●Line 107-109 : Uncommented and added # Postfix smtp-auth unix_listener /var/spool/postfix/private/auth { mode = 0666 user = postfix group = postfix } |
2.5 Edit 10-ssl.conf file
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# vi /etc/dovecot/conf.d/10-ssl.conf ●Per line 8 : Change ssl = yes |
2.6 Register dovecot as a service and start
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# systemctl enable dovecot.service Created symlink /etc/systemd/system/multi-user.target.wants/dovecot.service → /usr/lib/systemd/system/dovecot.service. # systemctl is-enabled dovecot.service Enabled # systemctl start dovecot.service |
2.7 Permission port opening for POP/IMAP service with firewalld
POP is [110/TCP], IMAP is [143/TCP].
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# firewall-cmd --permanent --add-service=pop3 # firewall-cmd --permanent --add-service=imap # firewall-cmd --reload |
3.Create mail user and check operation
3.1 advance preparation
①Pretreatment for new users
When a new user is added, set up the system to automatically send and receive e-mail.
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# mkdir -p /etc/skel/Maildir/{new,cur,tmp} # chmod -R 700 /etc/skel/Maildir/ # echo "~/Maildir/"> /etc/skel/.forward # chmod 600 /etc/skel/.forward |
Configure the already created users to be able to send and receive e-mail.
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# mkdir -p /home/huong/Maildir/{new,cur,tmp} # chown -R huong:huong /home/huong/Maildir/ # chmod 700 /home/huong/Maildir # chmod 700 /home/huong/Maildir/{new,cur,tmp} |
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Mail client installation # dnf -y install mailx # echo 'export MAIL=$HOME/Maildir' >> /etc/profile.d/mail.sh Add user [linux] # useradd linux # passwd linux Set password for user linux New password: Retype new password: passwd: all authentication tokens updated successfully. |
3.3 operation check ①
①Log in as an email user and send a test email.
①Log in as an email user and send a test email.
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# su - linux $ mail linux@localhost Subject: Test Mail mail test . ← To end the text, type ". " Enter EOT $ mail Heirloom Mail version 12.5 7/5/10. Type ? for help. "/home/linux/Maildir": 1 message 1 new >N 1 linux@korodes.com Fri Jul 15 22:26 17/510 "Test Mail" & 1 Message 1: From linux@korodes.com Fri Jul 15 22:26:39 2022 Return-Path: <linux@korodes.com> X-Original-To: linux@localhost Delivered-To: linux@localhost Date: Fri, 15 Jul 2022 22:26:39 +0900 To: linux@localhost Subject: Test Mail User-Agent: Heirloom mailx 12.5 7/5/10 Content-Type: text/plain; charset=us-ascii From: linux@korodes.com Status: Rmail test& |
3.4 operation check ②
Set up and confirm your account in Mozilla Thunderbird
Set up and confirm your account in Mozilla Thunderbird
①Start Thunderbird, and click "Tools", "Account Settings".
②「Account Actions」「Add Mail Account」
③Set as follows
Your full name : Any name
Email addtess : huong@korodes.com
Password : Password for user huong
Click on "Configure manually"
④Set "INCOMMING SERVER" and "OUTGOING SERVER" as shown below and click "Re-test".
⑤[The following settings were found by probinfg the given server] is displayed
After clicking "Done," the following "Warning" appears, but there is no problem, so click "Confirm.
⑥Click "Finish" when "Account syccessfuly created" is displayed.
Mail Server : Postfix + Clamav + Amavisd+SpamAssassin
1.Real-time scanning of e-mails
①Amavisd & Clamav Server Install
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# dnf --enablerepo=epel,powertools -y install amavisd-new clamd perl-Digest-SHA1 perl-IO-stringy |
➁Configuration File Editing
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# vi /etc/clamd.d/scan.conf ●Line 77： Change PidFile /var/run/clamd.scan/clamd.pid ●Line 81： Uncomment TemporaryDirectory /var/tmp ●Line 96： Change LocalSocket /var/run/clamd.scan/clamd.sock |
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# touch /var/log/clamd.scan # chown clamscan. /var/log/clamd.scan # systemctl enable clamd@scan |
➂Setup and start Amavisd
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# vi /etc/amavisd/amavisd.conf ●Per line 13 : Delete # at the beginning of the line @bypass_spam_checks_maps = (1); # controls running of anti-spam code ● Line 23： Change to your domain name $mydomain = 'Domain Name'; ●Per line 28 : comment-out #$QUARANTINEDIR = undef; # -Q ●Per line 125 : comment-out # $virus_admin = undef; # notifications recip ●Line 158： Uncomment and change to own host name $myhostname = 'mail.Domain Name'; # systemctl start amavisd # systemctl enable amavisd Created symlink /etc/systemd/system/multi-user.target.wants/amavisd.service → /usr/lib/systemd/system/amavisd.service. |
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# vi /etc/postfix/main.cf # Add to the last line content_filter=smtp-amavis:[127.0.0.1]:10024 # vi /etc/postfix/master.cf # Add to the last line smtp-amavis unix - - n - 2 smtp -o smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o disable_dns_lookups=yes 127.0.0.1:10025 inet n - 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 smtpd_error_sleep_time=0 -o smtpd_soft_error_limit=1001 -o smtpd_hard_error_limit=1000 |
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# systemctl restart postfix |
⑤I sent a test email to myself in Thunderbird, and in the header display section of the received email, I see the following
X-Virus-Scanned: amavisd-new at korodes.
X-Virus-Scanned: amavisd-new at korodes.
2.Email spam protection
①SpamAssassin installed to prevent spam
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# dnf -y install spamassassin spamass-milter-postfix # systemctl start spamassassin # systemctl enable spamassassin Created symlink /etc/systemd/system/multi-user.target.wants/spamassassin.service → /usr/lib/systemd/system/spamassassin.service. |
②SpamAssassin Settings
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# vi /etc/mail/spamassassin/v310.pre ●Per line 24 : Remove # at the beginning of the line loadplugin Mail::SpamAssassin::Plugin::DCC |
③SpamAssassin configuration file modernization script
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# cd /var/www/system # vi /var/www/system/spamassassin-update.sh #!/bin/bash cd /etc/mail/spamassassin wget -q https://github.com/kittyfreak/spamassassin_user_prefs/archive/refs/heads/main.zip [ $? -ne 0 ] && exit unzip main.zip >/dev/null 2>&1 [ $? -ne 0 ] && exit rm -f main.zip mv spamassassin_user_prefs-main/user_prefs . rm -rf spamassassin_user_prefs-main diff user_prefs user_prefs.org > /dev/null 2>&1 if [ $? -ne 0 ]; then cp user_prefs local.cf echo "report_safe 0" >> local.cf echo "rewrite_header Subject ***SPAM***" >> local.cf # SpamAssassin再起動 if [ -f /etc/rc.d/init.d/spamassassin ]; then /etc/rc.d/init.d/spamassassin restart > /dev/null else systemctl restart spamassassin > /dev/null fi fi cp user_prefs user_prefs.org |
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# chmod 700 /var/www/system/spamassassin-update.sh # /var/www/system/spamassassin-update.sh |
Check that the SpamAssassin configuration file is created in the /etc/mail/spamassassin directory with the date of the day.
SpamAssassin configuration file is created as of the current date.
SpamAssassin configuration file is created as of the current date.
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# ls -l /etc/mail/spamassassin total 1512 drwxr-xr-x 2 root root 40 Jul 15 22:38 channel.d -rw-r--r-- 1 root root 985 Apr 19 07:39 init.pre -rw-r--r-- 1 root root 499337 Jul 15 22:55 local.cf drwx------ 2 root root 6 Apr 19 07:39 sa-update-keys -rw-r--r-- 1 root root 62 Apr 19 07:39 spamassassin-default.rc -rwxr-xr-x 1 root root 35 Apr 19 07:39 spamassassin-helper.sh -rw-r--r-- 1 root root 55 Apr 19 07:39 spamassassin-spamc.rc -rw-r--r-- 1 root root 499289 Dec 29 2021 user_prefs -rw-r--r-- 1 root root 499289 Jul 15 22:55 user_prefs.org -rw-r--r-- 1 root root 2523 Jul 15 22:53 v310.pre -rw-r--r-- 1 root root 1194 Apr 19 07:39 v312.pre -rw-r--r-- 1 root root 2416 Apr 19 07:39 v320.pre -rw-r--r-- 1 root root 1237 Apr 19 07:39 v330.pre -rw-r--r-- 1 root root 1020 Apr 19 07:39 v340.pre -rw-r--r-- 1 root root 1114 Apr 19 07:39 v341.pre -rw-r--r-- 1 root root 1313 Apr 19 07:39 v342.pre -rw-r--r-- 1 root root 1264 Apr 19 07:39 v343.pre |
Set up cron to automatically run a script daily that updates the SpamAssassin configuration file
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# crontab -e 0 2 * * * /var/www/system/spamassassin-update.sh > /dev/null 2>&1 |
④Integrate SpamAssassin into Postfix
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# vi /etc/postfix/master.cf ●Per line 12. Add "#" to the beginning of the line and add SpamAssassin setting to line 13 # smtp inet n - n - - smtpd smtp inet n - n - - smtpd -o content_filter=spamassassin ●Add to last line smtp-amavis unix - - n - 2 smtp -o smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o disable_dns_lookups=yes 127.0.0.1:10025 inet n - 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 smtpd_error_sleep_time=0 -o smtpd_soft_error_limit=1001 -o smtpd_hard_error_limit=1000 spamassassin unix - n n - - pipe user=nobody argv=/usr/bin/spamc -e /usr/sbin/sendmail.postfix -oi -f ${sender} ${recipient} |
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# systemctl restart postfix |
⑥When you send a blank email to yourself in Thunderbird, you will see the following in the header
