#!/bin/sh

# Variáveis
# -------------------------------------------------------
iptables=/usr/sbin/iptables
IF_EXTERNA=eth0
IF_INTERNA=eth1


# Ativa módulos
# -------------------------------------------------------
/sbin/modprobe iptable_nat
/sbin/modprobe ip_conntrack
/sbin/modprobe ip_conntrack_ftp
/sbin/modprobe ip_nat_ftp
/sbin/modprobe ipt_LOG
/sbin/modprobe ipt_REJECT
/sbin/modprobe ipt_MASQUERADE


# Ativa roteamento no kernel
# -------------------------------------------------------
echo "1" > /proc/sys/net/ipv4/ip_forward

# Proteção contra IP spoofing
# -------------------------------------------------------
echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter

# Zera regras
# -------------------------------------------------------
$iptables -F
$iptables -X
$iptables -F -t nat
$iptables -X -t nat
$iptables -F -t mangle
$iptables -X -t mangle


# Determina a política padrão
# -------------------------------------------------------
$iptables -P INPUT DROP
$iptables -P OUTPUT DROP
$iptables -P FORWARD DROP


#################################################
# Tabela FILTER
#################################################


# Dropa pacotes TCP indesejáveis
# -------------------------------------------------------
$iptables -A FORWARD -p tcp ! --syn -m state --state NEW -j LOG --log-level 6 --log-prefix "FIREWALL: NEW sem syn: "
$iptables -A FORWARD -p tcp ! --syn -m state --state NEW -j DROP


# Dropa pacotes mal formados
# -------------------------------------------------------
# A estudar essas regras.
#$iptables -A INPUT -i $IF_EXTERNA -m unclean -j LOG --log-level 6 --log-prefix "FIREWALL: pacote mal formado: "
#$iptables -A INPUT -i $IF_EXTERNA -m unclean -j DROP


# Aceita os pacotes que realmente devem entrar
# -------------------------------------------------------
$iptables -A INPUT -i ! $IF_EXTERNA -j ACCEPT
$iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$iptables -A OUTPUT -m state --state ESTABLISHED,RELATED,NEW -j ACCEPT
$iptables -A FORWARD -m state --state ESTABLISHED,RELATED,NEW -j ACCEPT


# Proteção contra trinoo
# -------------------------------------------------------
$iptables -N TRINOO
$iptables -A TRINOO -m limit --limit 15/m -j LOG --log-level 6 --log-prefix "FIREWALL: trinoo: "
$iptables -A TRINOO -j DROP
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 27444 -j TRINOO
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 27665 -j TRINOO
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 31335 -j TRINOO
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 34555 -j TRINOO
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 35555 -j TRINOO


# Proteção contra tronjans
# -------------------------------------------------------
$iptables -N TROJAN
$iptables -A TROJAN -m limit --limit 15/m -j LOG --log-level 6 --log-prefix "FIREWALL: trojan: "
$iptables -A TROJAN -j DROP
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 666 -j TROJAN
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 666 -j TROJAN
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 4000 -j TROJAN
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 6000 -j TROJAN
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 6006 -j TROJAN
$iptables -A INPUT -p TCP -i $IF_EXTERNA --dport 16660 -j TROJAN


# Proteção contra worms
# -------------------------------------------------------
$iptables -A FORWARD -p tcp --dport 135 -i $IF_INTERNA -j REJECT


# Proteção contra syn-flood
# -------------------------------------------------------
$iptables -A FORWARD -p tcp --syn -m limit --limit 2/s -j ACCEPT


# Proteção contra ping da morte
# -------------------------------------------------------
$iptables -A FORWARD -p icmp --icmp-type echo-request -m limit --limit 1/s -j ACCEPT


# Proteção contra port scanners
# -------------------------------------------------------
$iptables -N SCANNER
$iptables -A SCANNER -m limit --limit 15/m -j LOG --log-level 6 --log-prefix "FIREWALL: port scanner: "
$iptables -A SCANNER -j DROP
$iptables -A INPUT -p tcp --tcp-flags ALL FIN,URG,PSH -i $IF_EXTERNA -j SCANNER
$iptables -A INPUT -p tcp --tcp-flags ALL NONE -i $IF_EXTERNA -j SCANNER
$iptables -A INPUT -p tcp --tcp-flags ALL ALL -i $IF_EXTERNA -j SCANNER
$iptables -A INPUT -p tcp --tcp-flags ALL FIN,SYN -i $IF_EXTERNA -j SCANNER
$iptables -A INPUT -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -i $IF_EXTERNA -j SCANNER
$iptables -A INPUT -p tcp --tcp-flags SYN,RST SYN,RST -i $IF_EXTERNA -j SCANNER
$iptables -A INPUT -p tcp --tcp-flags SYN,FIN SYN,FIN -i $IF_EXTERNA -j SCANNER


# Loga tentativa de acesso a determinadas portas
# -------------------------------------------------------
$iptables -A INPUT -p tcp --dport 21 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: ftp: "
$iptables -A INPUT -p tcp --dport 23 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: telnet: "
$iptables -A INPUT -p tcp --dport 25 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: smtp: "
#$iptables -A INPUT -p tcp --dport 80 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: http: "
$iptables -A INPUT -p tcp --dport 110 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: pop3: "
$iptables -A INPUT -p udp --dport 111 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: rpc: "
$iptables -A INPUT -p tcp --dport 113 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: identd: "
$iptables -A INPUT -p tcp --dport 137:139 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: samba: "
$iptables -A INPUT -p udp --dport 137:139 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: samba: "
$iptables -A INPUT -p tcp --dport 161:162 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: snmp: "
$iptables -A INPUT -p tcp --dport 6667:6668 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: irc: "
$iptables -A INPUT -p tcp --dport 3128 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: squid: "
$iptables -A INPUT -p tcp --dport 1433 -i $IF_EXTERNA -j LOG --log-level 6 --log-prefix "FIREWALL: sql - server: "


# Libera acesso externo a determinadas portas
# -------------------------------------------------------
#iptables -A INPUT -p tcp --dport 1433 -i $IF_EXTERNA -j ACCEPT
#iptables -A INPUT -p udp --dport 1433 -i $IF_EXTERNA -j ACCEPT
$iptables -A INPUT -p tcp --dport 80 -i $IF_EXTERNA -j ACCEPT
$iptables -A INPUT -p tcp --dport 80 -i $IF_INTERNA -j ACCEPT
$iptables -A INPUT -p tcp --dport 22 -i $IF_EXTERNA -j ACCEPT
$iptables -A INPUT -p tcp --dport 22 -i $IF_INTERNA -j ACCEPT

# ---------------------------------------------------------
# Fechando as portas do samba o perigo mora aqui caso fique de cara para a internet.
#$iptables -A INPUT -p tcp -i $IF_EXTERNA --syn --dport 139 -j DROP
#$iptables -A INPUT -p tcp -i $IF_EXTERNA --syn --dport 138 -j DROP
#$iptables -A INPUT -p tcp -i $IF_EXTERNA --syn --dport 137 -j DROP

# Fechando a porta do portmap
# ---------------------------------------------------------
iptables -A INPUT -p tcp -i $IF_EXTERNA --syn --dport 111 -j DROP
 
# Libera acesso de smtp para fora apenas para o IP XXX.XXX.XXX.XXX
# -------------------------------------------------------
#$iptables -A FORWARD -p tcp -d ! XXX.XXX.XXX.XXX --dport 25 -j LOG --log-level 6 --log-prefix "FIREWALL: SMTP proibido: "
#$iptables -A FORWARD -p tcp -d ! XXX.XXX.XXX.XXX --dport 25 -j REJECT

#################################################
# Tabela NAT
#################################################


# Ativa mascaramento de saída
# -------------------------------------------------------
$iptables -A POSTROUTING -t nat -o $IF_EXTERNA -j MASQUERADE

# Proxy transparente
# -------------------------------------------------------
#iptables -t nat -A PREROUTING -p tcp -m multiport -s 192.168.1.0/24 --dport 80,443 -j REDIRECT --to-ports 3128


## Tentativas com redirecionamento do SQL server.

# SQL que funcionou....
$iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 1433 -j DNAT --to-destination 192.168.1.140
$iptables -A FORWARD -i eth0 -o eth1 -p tcp --dport 1433 -d 192.168.1.140 -j ACCEPT
$iptables -t nat -A PREROUTING -i eth0 -p udp --dport 1433 -j DNAT --to-destination 192.168.1.140
$iptables -A FORWARD -i eth0 -o eth1 -p udp --dport 1433 -d 192.168.1.140 -j ACCEPT


# SQL  segunda tentativa.
#iptables -A FORWARD -i $IF_EXTERNA -p tcp --dport 1433 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
#iptables -A FORWARD -i $IF_EXTERNA -p udp --dport 1433 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
#iptables -t nat -A PREROUTING -p tcp -i $IF_EXTERNA --dport 1433 -j DNAT --to 192.168.1.140:1433
#iptables -t nat -A PREROUTING -p udp -i $IF_EXTERNA --dport 1433 -j DNAT --to 192.168.1.140:1433

# SQL  terceira tentativa
#iptables -A FORWARD -i $IF_EXTERNA -p tcp --dport 1433 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
#iptables -A FORWARD -i $IF_EXTERNA -p udp --dport 1433 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT

#iptables -t nat -A PREROUTING -p tcp --dport 1433 -d 200.204.198.164 -j DNAT --to 192.168.1.140
#iptables -t nat -A POSTROUTING -p tcp --sport 1433 -s 192.168.1.140 -j SNAT --to 201.204.198.164

# Redireciona portas na própria máquina vnc troque o ip conforme a máquina que deseja acessar.
#---------------------------------------------------------
iptables -A FORWARD -i $IF_EXTERNA -p tcp --dport 5800:5900 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -i $IF_EXTERNA -p udp --dport 5800:5900 -m state --state NEW,ESTABLISHED,RELATED -j ACCEPT
iptables -t nat -A PREROUTING -p tcp -i $IF_EXTERNA --dport 5800:5900 -j DNAT --to 192.168.1.140:5800-5900
iptables -t nat -A PREROUTING -p udp -i $IF_EXTERNA --dport 5800:5900 -j DNAT --to 192.168.1.140:5800-5900

# Redireciona portas para outros servidores
# -------------------------------------------------------
#$iptables -t nat -A PREROUTING -d 192.168.200.1 -p tcp --dport 22 -j DNAT --to-destination 10.0.0.1


# Redireciona portas na própria máquina
# -------------------------------------------------------
#$iptables -A PREROUTING -t nat -d 192.168.200.1 -p tcp --dport 5922 -j REDIRECT --to-ports 22