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Install Clam AntiVirus to protect servers from virus.

Install Clamav.

# install from EPEL

[root@dlp ~]# yum --enablerepo=epel -y install clamav clamav-update

[root@dlp ~]# sed -i -e "s/^Example/#Example/" /etc/freshclam.conf

# update pattern files

[root@dlp ~]# freshclam

ClamAV update process started at Fri Aug 29 22:03:30 2014 main.cld is up to date (version: 55, sigs: 2424225, f-level: 60, builder: neo) daily.cvd is up to date (version: 19314, sigs: 1094505, f-level: 63, builder: neo) bytecode.cvd is up to date (version: 242, sigs: 46, f-level: 63, builder: dgoddard)

Try to scan.

[root@dlp ~]# clamscan --infected --remove --recursive /home

----------- SCAN SUMMARY ----------- Known viruses: 3575245 Engine version: 0.98.4 Scanned directories: 2 Scanned files: 3 Infected files: 0 Data scanned: 0.00 MB Data read: 0.00 MB (ratio 0.00:1) Time: 10.369 sec (0 m 10 s) 

# download trial virus

[root@dlp ~]# curl -O http://www.eicar.org/download/eicar.com

[root@dlp ~]# clamscan --infected --remove --recursive .

./eicar.com: Eicar-Test-Signature FOUND

./eicar.com: Removed. # just detected

----------- SCAN SUMMARY ----------- Known viruses: 3575245 Engine version: 0.98.4 Scanned directories: 3 Scanned files: 10 Infected files: 1 Data scanned: 0.00 MB Data read: 256.57 MB (ratio 0.00:1) Time: 10.307 sec (0 m 10 s)

Install Amavisd and Clamav Server, and start Clamav Server first.

# install from EPEL

[root@mail ~]# yum --enablerepo=epel -y install amavisd-new clamav-server clamav-server-systemd

[root@mail ~]# cp /usr/share/doc/clamav-server*/clamd.sysconfig /etc/sysconfig/clamd.amavisd 

[root@mail ~]# vi /etc/sysconfig/clamd.amavisd

# line 1, 2: uncomment and change

CLAMD_CONFIGFILE=/etc/clamd.d/amavisd.conf

CLAMD_SOCKET=/var/run/clamd.amavisd/clamd.sock

[root@mail ~]# vi /etc/tmpfiles.d/clamd.amavisd.conf

# create new

d /var/run/clamd.amavisd 0755 amavis amavis -

[root@mail ~]# vi /usr/lib/systemd/system/clamd@.service

# add follows to the end

[Install]

WantedBy=multi-user.target

[root@mail ~]# systemctl start clamd@amavisd 

[root@mail ~]# systemctl enable clamd@amavisd 

ln -s '/usr/lib/systemd/system/clamd@.service' '/etc/systemd/system/multi-user.target.wants/clamd@amavisd.service'

Configure Amavisd.

[root@mail ~]# vi /etc/amavisd/amavisd.conf

# line 20: change to the own domain name

$mydomain = 'server.world';

# line 152: change to the own hostname

$myhostname = 'mail.server.world';

# line 154: uncomment

$notify_method = 'smtp:[127.0.0.1]:10025';

$forward_method = 'smtp:[127.0.0.1]:10025';

[root@mail ~]# systemctl start amavisd 

[root@mail ~]# systemctl enable amavisd 

[root@mail ~]# systemctl start spamassassin 

[root@mail ~]# systemctl enable spamassassin 

Configure Postfix.

[root@mail ~]# vi /etc/postfix/main.cf

# add follows to the end

content_filter=smtp-amavis:[127.0.0.1]:10024

[root@mail ~]# vi /etc/postfix/master.cf

# add follows to the end

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 

[root@mail ~]# systemctl restart postfix 

It' OK all.

These lines below are added in the header section of emails after this configuration and emails with known Virus will not sent to Clients.