#! /bin/bash
###############################################################################
# Autor: Tácio de Jesus Andrade
# Criação: 11/04/2011
# Modificação: 02/05/2011
# Função: Arquivo de Configuração Padrão do Firewall IpTables
# Utilização: Mova-o para o diretório /etc/init.d/ (em distros Debian-Like)
# e adicione o serviço para iniciar com o Sistema (pode-se utilizar
# o rcconf ou o comando de carregamento do serviço de sua distro)
###############################################################################case “$1″ in
start)
###############
# TITULO ABRE #
###############
echo “Iniciando a Configuração do Firewall”
########################
# Zera todas as Regras #
########################
echo “Regras Zeradas”
iptables -F
########################################
# Bloqueia tudo, nada entra e nada sai #
########################################
echo “Fechando tudo”
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT DROP
############################################################################
# Impede ataques DoS a maquina limitando a quantidade de respostas do ping #
############################################################################
#echo “Previne ataques DoS”
# iptables -A INPUT -p icmp –icmp-type echo-request -m limit –limit 1/s -j ACCEPT
#################################
# Bloqieia completamente o ping #
#################################
echo “Bloqueia o pings”
iptables -A INPUT -p icmp –icmp-type echo-request -j DROP
##########################
# Politicas de segurança #
##########################
echo “Implementação de politicas de segurança”
echo 0 > /proc/sys/net/ipv4/conf/all/accept_source_route # Impede falsear pacote
echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects # Perigo de descobrimento de rotas de roteamento (desativar em roteador)
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts # Risco de DoS
echo 1 > /proc/sys/net/ipv4/tcp_syncookies # Só inicia a conexão quando recebe a confirmação, diminuindo a banda gasta
echo 1 > /proc/sys/net/ipv4/conf/default/rp_filter # Faz o firewall responder apenas a placa de rede que recebeu o pacote
iptables -A INPUT -m state –state INVALID -j DROP # Elimina os pacotes invalidos
#################################
# Libera conexoes estabelecidas #
#################################
echo “Liberando conexões estabelecidas”
iptables -A INPUT -m state –state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -m state –state RELATED,ESTABLISHED,NEW -j ACCEPT
iptables -A OUTPUT -m state –state RELATED,ESTABLISHED,NEW -j ACCEPT
iptables -A INPUT -i lo -j ACCEPT
#######################################################################################
# Libera o acesso via SSH e Limita o número de tentativas de acesso a 4 a cada minuto #
#######################################################################################
#echo “Liberando o SSH”
# iptables -I INPUT -p tcp –dport 22 -i eth0 -m state –state NEW -m recent –update –seconds 60 –hitcount 4 -j DROP
# iptables -A INPUT -p tcp –dport 22 -j ACCEPT
# iptables -A INPUT -p udp –dport 22 -j ACCEPT
##################
# Libera o Samba #
##################
#echo “Liberando o Samba”
# iptables -A INPUT -p tcp –dport 137:139 -j ACCEPT
# iptables -A INPUT -p udp –dport 137:139 -j ACCEPT
###################
# Libera o Apache #
###################
#echo “Liberando o Apache”
# iptables -A INPUT -p tcp –dport 80 -j ACCEPT
################
# TITULO FECHA #
################
echo “Configuração do Firewall Concluida.”
;;
stop)
echo “Finalizando o Firewall”
rm -rf /var/lock/subsys/firewall
# —————————————————————–
# Remove todas as regras existentes
# —————————————————————–
iptables -F
iptables -X
iptables -t mangle -F
# —————————————————————–
# Reseta as politicas padrões, aceitar tudo
# —————————————————————–
iptables -P INPUT ACCEPT
iptables -P OUTPUT ACCEPT
iptables -P FORWARD ACCEPT
;;
restart|reload)
$0 stop
$0 start
;;
*)
echo “Selecione uma opção valida {start|stop|status|restart|reload}”
exit 1
esac
exit 0
