firewall seguro?

paulocdc
(usa Debian)

Enviado em 26/02/2008 - 09:59h

Gostaria de saber se meu firewall e seguro. e se vcs quizerem contribuir com mais alguma coisa fica grato.

#!/bin/sh

echo "####################ATIVANDO IPTABLES#######################"
### Passo 1: Limpando as regras ###
iptables -F INPUT
iptables -F OUTPUT
iptables -F FORWARD
iptables -F POSTROUTING -t nat
iptables -F PREROUTING -t nat
iptables -F -t nat

echo "Limpando as regras ..................................[ OK ]"

# Definindo a Politica Default das Cadeias
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -P OUTPUT ACCEPT
echo "Politica Default das Cadeias ........................[ OK ]"

### Passo 2: Desabilitar o trafego IP entre as placas de rede ###
echo "0" > /proc/sys/net/ipv4/ip_forward
echo "Desabilitar o trafego IP entre as placas ............[ OK ]"

# Configurando a Protecao anti-spoofing
echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter
#for spoofing in /proc/sys/net/ipv4/conf/*/rp_filter; do
# echo "1" > $spoofing
#done
echo "Protecao anti-spoofing ..............................[ OK ]"
###########setando protecao contra ataques
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
echo 1 > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts
echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
for i in /proc/sys/net/ipv4/conf/*; do
echo 0 >$i/accept_redirects
echo 0 >$i/accept_source_route
echo 1 >$i/log_martians
echo 1 >$i/rp_filter;
done
echo "Protecao contra ataques .............................[ OK ]"

# Impedimos que um atacante possa maliciosamente alterar alguma rota
echo 0 > /proc/sys/net/ipv4/conf/all/accept_redirects
echo "Impedimos alterar alguma rota .......................[ OK ]"

# Utilizado em diversos ataques, isso possibilita que o atacante determine o "caminho" que seu
# pacote vai percorrer (roteadores) ate seu destino. Junto com spoof, isso se torna muito perigoso.
echo 0 > /proc/sys/net/ipv4/conf/all/accept_source_route
echo "Impossibilita que o atacante determine o "caminho" ....[ OK ]"

# Protecao contra responses bogus
echo 1 > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses
echo "Protecao contra responses bogus .....................[ OK ]"

# Protecao contra ataques de syn flood (inicio da conexao TCP). Tenta conter ataques de DoS.
echo 1 > /proc/sys/net/ipv4/tcp_syncookies
echo "Protecao contra ataques de syn ......................[ OK ]"

### Passo 3: Carregando os modulos do iptables ###
# Ativa modulos
# -------------------------------------------------------
/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
echo "Carregando os modulos ...............................[ OK ]"


### Passo 4: Agora, vamos definir o que pode passar e o que nao ###
# Cadeia de Entrada

#remote
iptables -A FORWARD -p tcp --dport 4899 -j ACCEPT
iptables -A INPUT -p tcp --dport 4899 -j ACCEPT
echo "Regras remote .......................................[ OK ]"


#terminal server
iptables -A INPUT -p tcp --dport 3389 -j ACCEPT
iptables -A FORWARD -p tcp --dport 3389 -j ACCEPT
echo "Regras terminal serv ................................[ OK ]"

######

# Redireciona porta 80 para 3128 (squid)
#iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128

# PORTA 3128 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 3128 -j ACCEPT


# PORTA 110 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 110 -j ACCEPT
iptables -A FORWARD -i eth0 -p udp --dport 110 -j ACCEPT

# PORTA 25 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 25 -j ACCEPT

# PORTA 443 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 443 -j ACCEPT

# PORTA 21 - ACEITA PARA A REDE LOCAL
#iptables -A INPUT -p tcp --dport 21 -j ACCEPT
iptables -A FORWARD -p tcp --dport 21 -j ACCEPT

# PORTA 20 - ACEITA PARA A REDE LOCAL
#iptables -A INPUT -p tcp --dport 20 -j ACCEPT
iptables -A FORWARD -p tcp --dport 20 -j ACCEPT
iptables -A INPUT -p tcp --syn --dport 22 -m recent --name sshattack --set
iptables -A INPUT -p tcp --dport 22 --syn -m recent --name sshattack --rcheck --seconds 60 --hitcount 3 -j LOG --log-prefix 'SSH REJECT: '
iptables -A INPUT -p tcp --dport 22 --syn -m recent --name sshattack --rcheck --seconds 60 --hitcount 3 -j REJECT --reject-with tcp-reset
iptables -A FORWARD -p tcp --syn --dport 22 -m recent --name sshattack --set
iptables -A FORWARD -p tcp --dport 22 --syn -m recent --name sshattack --rcheck --seconds 60 --hitcount 3 -j LOG --log-prefix 'SSH REJECT: '
iptables -A FORWARD -p tcp --dport 22 --syn -m recent --name sshattack --rcheck --seconds 60 --hitcount 3 -j REJECT --reject-with tcp-reset

######
# PORTA 3128 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 3128 -j ACCEPT

# Redireciona porta 80 para 3128 (squid)
#iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 80 -j REDIRECT --to-port 3128


# PORTA 53 - ACEITA PARA A REDE LOCAL

iptables -A FORWARD -i eth0 -p tcp --dport 53 -j ACCEPT
iptables -A FORWARD -i eth0 -p udp --dport 53 -j ACCEPT

# PORTA 110 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 110 -j ACCEPT
iptables -A FORWARD -i eth0 -p udp --dport 110 -j ACCEPT

# PORTA 25 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 25 -j ACCEPT

# PORTA 443 - ACEITA PARA A REDE LOCAL
iptables -A FORWARD -i eth0 -p tcp --dport 443 -j ACCEPT

# identd
iptables -A INPUT -p tcp --dport 113 -j ACCEPT
iptables -A INPUT -p udp --dport 113 -j ACCEPT

# https
iptables -A INPUT -p tcp --dport 443 -j ACCEPT
iptables -A INPUT -p udp --dport 443 -j ACCEPT

# PORTA 21 - ACEITA PARA A REDE LOCAL
#iptables -A INPUT -p tcp --dport 21 -j ACCEPT
iptables -A FORWARD -p tcp --dport 21 -j ACCEPT

# PORTA 20 - ACEITA PARA A REDE LOCAL
#iptables -A INPUT -p tcp --dport 20 -j ACCEPT
iptables -A FORWARD -p tcp --dport 20 -j ACCEPT

#bloqueia qualquer tentativa de nova conexao de fora para esta maquina
iptables -A INPUT -i eth1 -m state --state ! ESTABLISHED,RELATED -j LOG --log-level 6 --log-prefix "FIREWALL entrada "
iptables -A INPUT -i eth1 -m state --state ! ESTABLISHED,RELATED -j DROP

#no iptables, temos de dizer quais sockets sao validos em uma conexao
iptables -A INPUT -m state --state ESTABLISHED,RELATED,NEW -j ACCEPT
echo "Cadeia de Entrada ...................................[ OK ]"

################################
# Cadeia de Reenvio (FORWARD).
# Primeiro, ativar o mascaramento (nat).
iptables -t nat -F POSTROUTING
iptables -t nat -A POSTROUTING -o eth1 -j MASQUERADE
echo "Ativando o mascaramento .............................[ OK ]"

# Agora dizemos quem e o que podem acessar externamente
# O controle do acesso a rede externa e feito na cadeia "FORWARD"
iptables -A FORWARD -i eth1 -j ACCEPT
iptables -A FORWARD -o eth1 -m state --state ESTABLISHED,RELATED -j ACCEPT
echo "Ativando o acesso ftp.. .............................[ OK ]"



###################
###BLOQUEANDO TODAS AS SAIDAS E PORTAS
iptables -A INPUT -p all -j DROP
iptables -A FORWARD -p all -j DROP
echo "Rejeitando saida e entrada ..........................[ OK ]"
########################

# No iptables, temos de dizer quais sockets sao validos em uma conexao

iptables -A FORWARD -m state --state ESTABLISHED,RELATED,NEW -j ACCEPT
echo "Quais sockets sao validos ...........................[ OK ]"

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

# Proteção contra tronjans
# -------------------------------------------------------
iptables -A INPUT -p TCP -i eth1 --dport 666 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 4000 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 6000 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 6006 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 16660 -j DROP

# Proteção contra trinoo
# -------------------------------------------------------
iptables -A INPUT -p TCP -i eth1 --dport 27444 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 27665 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 31335 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 34555 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 35555 -j DROP
echo "Proteção contra trinoo ............................. [ OK ]"

# Protecao contra acesso externo squid
# -------------------------------------------------------
iptables -A INPUT -p TCP -i eth1 --dport 3128 -j DROP
iptables -A INPUT -p TCP -i eth1 --dport 8080 -j DROP
echo "Proteção contra squid externo....................... [ OK ]"

# Protecao contra telnet
# -------------------------------------------------------
iptables -A INPUT -p TCP -i eth1 --dport telnet -j DROP
echo "Proteção contra telnet ....................... [ OK ]"

# Dropa pacotes TCP indesejáis
# -------------------------------------------------------
iptables -A FORWARD -p tcp ! --syn -m state --state NEW -j DROP
# Dropa pacotes mal formados
# -------------------------------------------------------
#iptables -A INPUT -i eth1 -m unclean -j DROP
# Proteç contra worms
# -------------------------------------------------------
iptables -A FORWARD -p tcp --dport 135 -i eth1 -j REJECT
# Proteç contra syn-flood
# -------------------------------------------------------
iptables -A FORWARD -p tcp --syn -m limit --limit 2/s -j ACCEPT
# Proteç contra ping da morte
# -------------------------------------------------------
iptables -A FORWARD -p icmp --icmp-type echo-request -m limit --limit 1/s -j ACCEPT
echo "Caregando tabela filter ............................ [ OK ]"
#Allow ALL other forwarding going out
iptables -A FORWARD -o eth1 -i eth0 -j ACCEPT

#################################################
# FIM DA Tabela FILTER
#################################################
# Proteção contra port scanners
# -------------------------------------------------------
#iptables -N SCANNER
iptables -A SCANNER -m limit --limit 15/m -j LOG --log-prefix "FIREWALL: port scanner: "
iptables -A SCANNER -j DROP
iptables -A INPUT -p tcp --tcp-flags ALL FIN,URG,PSH -i eth1 -j SCANNER
iptables -A INPUT -p tcp --tcp-flags ALL NONE -i eth1 -j SCANNER
iptables -A INPUT -p tcp --tcp-flags ALL ALL -i eth1 -j SCANNER
iptables -A INPUT -p tcp --tcp-flags ALL FIN,SYN -i eth1 -j SCANNER
iptables -A INPUT -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -i eth1 -j SCANNER
iptables -A INPUT -p tcp --tcp-flags SYN,RST SYN,RST -i eth1 -j SCANNER
iptables -A INPUT -p tcp --tcp-flags SYN,FIN SYN,FIN -i eth1 -j SCANNER
echo "Scaner de Portas ....................................[ OK ]"

# Loga tentativa de acesso a determinadas portas
# -------------------------------------------------------
iptables -A INPUT -p tcp --dport 22 -i eth1 -j LOG --log-prefix "FIREWALL: ssh: "
iptables -A INPUT -p tcp --dport 21 -i eth1 -j LOG --log-prefix "FIREWALL: ftp: "
iptables -A INPUT -p tcp --dport 23 -i eth1 -j LOG --log-prefix "FIREWALL: telnet: "
iptables -A INPUT -p tcp --dport 25 -i eth1 -j LOG --log-prefix "FIREWALL: smtp: "
iptables -A INPUT -p tcp --dport 80 -i eth1 -j LOG --log-prefix "FIREWALL: http: "
iptables -A INPUT -p tcp --dport 110 -i eth1 -j LOG --log-prefix "FIREWALL: pop3: "
iptables -A INPUT -p udp --dport 111 -i eth1 -j LOG --log-prefix "FIREWALL: rpc: "
iptables -A INPUT -p tcp --dport 113 -i eth1 -j LOG --log-prefix "FIREWALL: identd: "
iptables -A INPUT -p tcp --dport 137:139 -i eth1 -jLOG --log-prefix "FIREWALL: samba: "
iptables -A INPUT -p udp --dport 137:139 -i eth1 -j LOG --log-prefix "FIREWALL: samba: "
iptables -A INPUT -p tcp --dport 161:162 -i eth1 -j LOG --log-prefix "FIREWALL: snmp: "
iptables -A INPUT -p tcp --dport 6667:6668 -i eth1 -j LOG --log-prefix "FIREWALL: irc: "
iptables -A INPUT -p tcp --dport 3128 -i eth1 -j LOG --log-prefix "FIREWALL: squid: "
echo "Negando portas indesejadas ..........................[ OK ]"

# Libera acesso externo a determinadas portas

##Algumas portas devem ser negadas.
iptables -A INPUT -p tcp --dport 1433 -j DROP
iptables -A INPUT -p tcp --dport 6670 -j DROP
iptables -A INPUT -p tcp --dport 6711 -j DROP
iptables -A INPUT -p tcp --dport 6712 -j DROP
iptables -A INPUT -p tcp --dport 6713 -j DROP
iptables -A INPUT -p tcp --dport 12345 -j DROP
iptables -A INPUT -p tcp --dport 12346 -j DROP
iptables -A INPUT -p tcp --dport 20034 -j DROP
iptables -A INPUT -p tcp --dport 31337 -j DROP
iptables -A INPUT -p tcp --dport 6000 -j DROP
echo "Negando portas invalidas ............................[ OK ]"

#Traceroutes caindo

iptables -A INPUT -p udp --dport 33434:33523 -j DROP
iptables -A INPUT -p tcp --dport 113 -j REJECT
iptables -A INPUT -p igmp -j REJECT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j REJECT

echo "Rejeitando lixo :....................................[ OK ]"

# Finalmente: Habilitando o trafego IP, entre as Interfaces de rede
echo "1" > /proc/sys/net/ipv4/ip_forward
echo "Habilitar o trafego IP entre as placas: .............[ OK ]"

echo "##################FIM DE REGRAS IPTABLES####################"
exit 0