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Dopadł Cię już ten denerwujący bot który skanuje Cię nagminnie generując zbędny transfer i zapycha łącze? W tym cennym poradniku postaram się opisać na przykładzie debian’a jak zablokować mu i innym botom dostęp do “włamywania się”.

Zainstaluj program fail2ban z repozytoriów:

apt-get install fail2ban

Teraz przejdź do /etc/fail2ban/action.d/iptables-allports.conf

dopisz i porównaj zawartość z poniższym tekstem:

# Fail2Ban configuration file
#
# Author: Cyril Jaquier
# Modified: Yaroslav O. Halchenko <debian@onerussian.com>
#             made active on all ports from original iptables.conf
#
# $Revision: 658 $
#

[Definition]

# Option:  actionstart
# Notes.:  command executed once at the start of Fail2Ban.
# Values:  CMD
#
actionstart = iptables -N fail2ban-<name>
              iptables -A fail2ban-<name> -j RETURN
              iptables -I INPUT -p <protocol> -j fail2ban-<name>

# Option:  actionstop
# Notes.:  command executed once at the end of Fail2Ban
# Values:  CMD
#
actionstop = iptables -D INPUT -p <protocol> -j fail2ban-<name>
             iptables -F fail2ban-<name>
             iptables -X fail2ban-<name>

# Option:  actioncheck
# Notes.:  command executed once before each actionban command
# Values:  CMD
#
actioncheck = iptables -n -L INPUT | grep -q fail2ban-<name>

# Option:  actionban
# Notes.:  command executed when banning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    <ip>  IP address
#          <failures>  number of failures
#          <time>  unix timestamp of the ban time
# Values:  CMD
#
actionban = iptables -I fail2ban-<name> 1 -s <ip> -j DROP

# Option:  actionunban
# Notes.:  command executed when unbanning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    <ip>  IP address
#          <failures>  number of failures
#          <time>  unix timestamp of the ban time
# Values:  CMD
#
actionunban = iptables -D fail2ban-<name> -s <ip> -j DROP

[Init]

# Defaut name of the chain
#
name = default

# Option:  protocol
# Notes.:  internally used by config reader for interpolations.
# Values:  [ tcp | udp | icmp | all ] Default: tcp
#
protocol = all

# Fail2Ban configuration file
#
# Author: Cyril Jaquier
# Modified: Yaroslav O. Halchenko <debian@onerussian.com>
#             made active on all ports from original iptables.conf
#
# $Revision: 658 $
#

[Definition]

# Option:  actionstart
# Notes.:  command executed once at the start of Fail2Ban.
# Values:  CMD
#
actionstart = iptables -N fail2ban-<name>
              iptables -A fail2ban-<name> -j RETURN
              iptables -I INPUT -p <protocol> -j fail2ban-<name>

# Option:  actionstop
# Notes.:  command executed once at the end of Fail2Ban
# Values:  CMD
#
actionstop = iptables -D INPUT -p <protocol> -j fail2ban-<name>
             iptables -F fail2ban-<name>
             iptables -X fail2ban-<name>

# Option:  actioncheck
# Notes.:  command executed once before each actionban command
# Values:  CMD
#
actioncheck = iptables -n -L INPUT | grep -q fail2ban-<name>

# Option:  actionban
# Notes.:  command executed when banning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    <ip>  IP address
#          <failures>  number of failures
#          <time>  unix timestamp of the ban time
# Values:  CMD
#
actionban = iptables -I fail2ban-<name> 1 -s <ip> -j DROP

# Option:  actionunban
# Notes.:  command executed when unbanning an IP. Take care that the
#          command is executed with Fail2Ban user rights.
# Tags:    <ip>  IP address
#          <failures>  number of failures
#          <time>  unix timestamp of the ban time
# Values:  CMD
#
actionunban = iptables -D fail2ban-<name> -s <ip> -j DROP

[Init]

# Defaut name of the chain
#
name = default

# Option:  protocol
# Notes.:  internally used by config reader for interpolations.
# Values:  [ tcp | udp | icmp | all ] Default: tcp
#
protocol = all

czyli uzupełnij poprawnie ostatnią linijkę.

Następnie utwórz

/etc/fail2ban/filter.d/apache-w00tw00t.conf

dopisz i porównaj zawartość z poniższym tekstem:

#<HOST> - - [29/Apr/2008:22:54:08 +0200] "GET /w00tw00t.at.ISC.SANS.DFind:) HTTP/1.1" 400 326

[Definition]

# Option:  failregex
# Notes.:  regex to match the w00tw00t scan messages in the logfile. The
#          host must be matched by a group named "host". The tag "<HOST>" can
#          be used for standard IP/hostname matching.
# Values:  TEXT
failregex = ^<HOST> -.*"GET \/w00tw00t\.at\.ISC\.SANS\.DFind\:\).*".*

# Option:  ignoreregex
# Notes.:  regex to ignore. If this regex matches, the line is ignored.
# Values:  TEXT

ignoreregex =

Wyedytuj plik /etc/fail2ban/jail.conf i wstaw poniższą zawartość np. na końcu tego pliku:

[apache-w00tw00t]
enabled  = true
filter   = apache-w00tw00t
action   = iptables-allports[name=w00tw00t]
           mail-whois[name=w00tw00t, dest=<YOURMAIL>]
logpath  = /var/log/apache2/access_log
maxretry = 1
bantime  = 86400

Zrestartuj fail2ban poleceniem:

/etc/init.d/fail2ban restart