Cegah Brute Force Attack Menggunakan fail2ban

fail2ban adalah aplikasi yang berfungsi untuk mencegah serangan Brute Force. Oke langsung aja…

1. Install fail2ban

#yum -y install fail2ban

2. Buat sistem startup link untuk fail2ban dan jalankan

Code:

#chkconfig –levels 235 fail2ban on
# /etc/init.d/fail2ban start

3. Coba login ke ssh, dan masukan 3 password yg salah. Nanti IP kamu akan di blokir selama 10 menit.

4. Untuk liat log nya

Code:

# tail -f /var/log/fail2ban.log

contoh isi log

Code:

2011-06-28 22:27:58,953 fail2ban.jail : INFO Jail ‘ssh’ started
2011-06-28 22:29:36,430 fail2ban.actions: WARNING [ssh] Ban 192.168.1.18

5. Konfigurasi fail2ban

Code:

vi  /etc/fail2ban/jail.conf

————————————————————

# Fail2Ban configuration file
#
# Author: Cyril Jaquier
#
# $Revision: 617 $
#

# The DEFAULT allows a global definition of the options. They can be override
# in each jail afterwards.

[DEFAULT]

# "ignoreip" can be an IP address, a CIDR mask or a DNS host. Fail2ban will not
# ban a host which matches an address in this list. Several addresses can be
# defined using space separator.
ignoreip = 127.0.0.1 192.168.0.99

# "bantime" is the number of seconds that a host is banned.
bantime  = 600

# A host is banned if it has generated "maxretry" during the last "findtime"
# seconds.
findtime  = 600

# "maxretry" is the number of failures before a host get banned.
maxretry = 3

# "backend" specifies the backend used to get files modification. Available
# options are "gamin", "polling" and "auto". This option can be overridden in
# each jail too (use "gamin" for a jail and "polling" for another).
#
# gamin:   requires Gamin (a file alteration monitor) to be installed. If Gamin
#          is not installed, Fail2ban will use polling.
# polling: uses a polling algorithm which does not require external libraries.
# auto:    will choose Gamin if available and polling otherwise.
backend = auto

[ssh-iptables]

enabled  = true
filter   = sshd
action   = iptables[name=SSH, port=ssh, protocol=tcp]
           sendmail-whois[name=SSH, dest=you@mail.com, sender=fail2ban@mail.com]
logpath  = /var/log/secure
maxretry = 5

[proftpd-iptables]

enabled  = true
filter   = proftpd
action   = iptables[name=ProFTPD, port=ftp, protocol=tcp]
           sendmail-whois[name=ProFTPD, dest=you@mail.com]
logpath  = /var/log/secure
maxretry = 6

[sasl-iptables]

enabled  = true
filter   = sasl
backend  = polling
action   = iptables[name=sasl, port=smtp, protocol=tcp]
           sendmail-whois[name=sasl, dest=you@mail.com]
logpath  = /var/log/maillog

[apache-tcpwrapper]

enabled  = true
filter   = apache-auth
action   = hostsdeny
logpath  = /var/log/httpd/*error_log
maxretry = 6

[postfix-tcpwrapper]

enabled  = true
filter   = postfix
action   = hostsdeny
           sendmail[name=Postfix, dest=you@mail.com]
logpath  = /var/log/maillog
bantime  = 300

[courierpop3]

enabled  = true
port     = pop3
filter   = courierlogin
action   = iptables[name=%(__name__)s, port=%(port)s]
logpath  = /var/log/maillog
maxretry = 5

[courierimap]

enabled  = true
port     = imap2
filter   = courierlogin
action   = iptables[name=%(__name__)s, port=%(port)s]
logpath  = /var/log/maillog
maxretry = 5

[ssh-tcpwrapper]

enabled     = false
filter      = sshd
action      = hostsdeny
              sendmail-whois[name=SSH, dest=you@mail.com]
ignoreregex = for myuser from
logpath     = /var/log/secure

[vsftpd-notification]

enabled  = false
filter   = vsftpd
action   = sendmail-whois[name=VSFTPD, dest=you@mail.com]
logpath  = /var/log/secure
maxretry = 5
bantime  = 1800

[vsftpd-iptables]

enabled  = false
filter   = vsftpd
action   = iptables[name=VSFTPD, port=ftp, protocol=tcp]
           sendmail-whois[name=VSFTPD, dest=you@mail.com]
logpath  = /var/log/secure
maxretry = 5
bantime  = 1800

[apache-badbots]

enabled  = false
filter   = apache-badbots
action   = iptables-multiport[name=BadBots, port="http,https"]
           sendmail-buffered[name=BadBots, lines=5, dest=you@mail.com]
logpath  = /var/log/httpd/*access_log
bantime  = 172800
maxretry = 1

[apache-shorewall]

enabled  = false
filter   = apache-noscript
action   = shorewall
           sendmail[name=Apache, dest=you@mail.com]
logpath  = /var/log/httpd/error_log

[ssh-ipfw]

enabled  = false
filter   = sshd
action   = ipfw[localhost=192.168.0.1]
           sendmail-whois[name="SSH,IPFW", dest=you@mail.com]
logpath  = /var/log/secure
ignoreip = 168.192.0.1

[named-refused-udp]

enabled  = false
filter   = named-refused
action   = iptables-multiport[name=Named, port="domain,953", protocol=udp]
           sendmail-whois[name=Named, dest=you@mail.com]
logpath  = /var/log/secure
ignoreip = 168.192.0.1

[named-refused-tcp]

enabled  = false
filter   = named-refused
action   = iptables-multiport[name=Named, port="domain,953", protocol=tcp]
           sendmail-whois[name=Named, dest=you@mail.com]
logpath  = /var/log/secure
ignoreip = 168.192.0.1
------------------------------------------------------------




Jangan lupa mengganti you@mail.com dengan email kamu.
Setelah konfigurasi lakukan restart

Code:

# /etc/init.d/fail2ban restart