Script(ino) per IPTables

Volevo mettere su uno script(ino) per IPTables per:

- permettere tutto il traffico in uscita dal mio PC
- bloccare tutto il traffico in ingresso al mio PC, a meno che questo non sia conseguenza di una connessione/richiesta iniziata dal mio PC.

Ho scritto questo.

Codice: Seleziona tutto

IPTABLES="/sbin/iptables"

echo "Step 0 - Starting firewall ..."

echo "Step 1 - Setting rules ..."

$IPTABLES -P INPUT DROP
$IPTABLES -P FORWARD DROP
$IPTABLES -P OUTPUT ACCEPT

$IPTABLES -A INPUT -i lo -j ACCEPT

$IPTABLES -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A FORWARD -i eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT


L'ho testato e sembra funzionare bene ... qualche esperto ha qualche suggerimento?

Io tempo fa avevo fatto uno scriptino un po' più estensibile. Se vuoi dagli un'occhiata.
Per usarlo devi creare il gruppo "nonet", che è quello bannato dall'accesso alla rete. Lo uso per dare il setgid ad un programma che non voglio che acceda a internet. Se non vuoi creare il gruppo allora elimina la catena relativa al ban del gruppo nonet

Codice: Seleziona tutto

#!/bin/sh

#Interfacce
IFACE=wlan0 #Interfaccia esterna ethernet
LFACE=eth0 #Interfaccia interna

#Nameservers
NAMESERVER_1=213.205.32.70
NAMESERVER_2=213.205.36.70

#Default gateway
GATEWAY=192.168.0.1

#Group to ban from net access
BAN_GROUP=nonet
#IP to ban from net access (list separated with spaces)
BAN_IP=""
#BAN_IP="192.168.0.200-192.168.0.255 192.168.0.110"
#IP to log if connection is detected
LOG_IP=""
#LOG_IP="192.168.0.200-192.168.0.255"

#INPUT FILES
#List of banned ip addresses
#INPUTF="/etc/blocklist_ip"
#if [ ! -f $INPUTF ]; then
#    echo ERROR! FILE $INPUTF NOT FOUND!
#    exit 1
#fi

#Port definitions
SSH_PORT=22
P_PORTS=0:1023
UP_PORTS=1024:65535
BITTORRENT_PORTS=6881:6889
TRANSMISSION_PORT=51413
EKIGA_PORTS=5000:5100

#Some stuff which usually is standard
IPTABLES=/sbin/iptables
IPTABLESSAVE=/sbin/iptables-save
IPTABLESRESTORE=/sbin/iptables-restore

##########################################################################
#Definisco i set di regole da caricare
##########################################################################
#Queste regole sono definite come funzioni da chiamare al momento di
#applicare le catene. Ogni funzione definisce le funzioni input, output e
#forward da applicare rispettivamente a INPUT, OUTPUT e FORWARD.
#A seconda dei parametri passati da riga di comando posso chiamare diversi
#set di regole. Se non specifico niente chiama il set di default.
#Ricordarsi sempre di aggiornare la lista dei parametri accettati.
#Le funzioni devono avere lo stesso nome dei parametri corrispondenti.
LISTA_PARAMETRI="default block forward status stop"

default() {
  input() {
    echo "FW: Carico set di regole 'default'"
    $IPTABLES -A INPUT -j ssh_in
    $IPTABLES -A INPUT -j transmission_in
    return 0
  }
  output() {
#    $IPTABLES -A OUTPUT -d 127.0.0.1 -j ACCEPT
#    $IPTABLES -A OUTPUT -d 10.0.2.2 -j ACCEPT
    $IPTABLES -A OUTPUT -j ban_group
    $IPTABLES -A OUTPUT -d 10.0.2.2 -j ACCEPT
    return 0
  }
  forward() {
    return 0
  }
}

forward() {
  input() {
    $IPTABLES -A INPUT -j ssh_in
    return 0
  }
  output() {
    $IPTABLES -A OUTPUT -j ban_group
    return 0
  }
  forward() {
    echo "FW: Forwarding dalla porta $LFACE a $GATEWAY"
    echo 1 > /proc/sys/net/ipv4/ip_forward
    iptables -t nat -A POSTROUTING -o $LFACE -j SNAT --to $GATEWAY
    return 0
  }
}

status() {
  echo "-------------- RULES STATUS : --------------"
  echo ""
  $IPTABLES -L -n -v --line-numbers
  echo ""
  echo "--------------- NAT STATUS : ---------------"
  echo ""
  $IPTABLES -L -n -v --line-numbers -t nat
  exit 0
}

stop() {
  echo "FW: Arresto del firewall (tutte le regole su ACCEPT)"
  #Clear all chains in all tables
  $IPTABLES -F
  $IPTABLES -F -t mangle
  $IPTABLES -F -t nat
  $IPTABLES -X
  $IPTABLES -X -t mangle
  $IPTABLES -X -t nat
  #Set Defaults to ACCEPT
  $IPTABLES -P INPUT ACCEPT
  $IPTABLES -P OUTPUT ACCEPT
  $IPTABLES -P FORWARD ACCEPT
  exit 0
}

block() {
  echo "FW: blocking all network trafic 'in' and 'out'"
  $IPTABLES -F
  $IPTABLES -F -t mangle
  $IPTABLES -F -t nat
  $IPTABLES -X
  $IPTABLES -X -t mangle
  $IPTABLES -X -t nat
  $IPTABLES -P FORWARD DROP
  $IPTABLES -P INPUT   DROP
  $IPTABLES -P OUTPUT  DROP
  $IPTABLES -A INPUT -i lo -j ACCEPT
  $IPTABLES -A OUTPUT -o lo -j ACCEPT
  exit 0
}

#Definisco quanto specificato da parametro.
if [ ${#@} -gt 0 ]; then
  if [ `echo $LISTA_PARAMETRI|grep -e $1|wc -l` -gt 0 ]; then
    $1
  else
    echo "parametro '$1' sconosciuto"
    echo "Lista dei parametri accettati:"
    echo $LISTA_PARAMETRI
    exit 0
  fi
else
  default
fi

##########################################################################
#Pulisco tutte le regole e ripristino quelle di default (ACCEPT)
##########################################################################
$IPTABLES -F
$IPTABLES -F -t mangle
$IPTABLES -F -t nat
$IPTABLES -X
$IPTABLES -X -t mangle
$IPTABLES -X -t nat
#Set Defaults to ACCEPT
$IPTABLES -P INPUT ACCEPT
$IPTABLES -P OUTPUT ACCEPT
$IPTABLES -P FORWARD ACCEPT

##########################################################################
#Definisco la policy di default
##########################################################################
$IPTABLES -P INPUT DROP
$IPTABLES -P FORWARD DROP
$IPTABLES -P OUTPUT ACCEPT

##########################################################################
#Definisco le catene per i vari tipi di paccehtti
##########################################################################
#Genero lista indirizzi da bloccare
# $IPTABLES -N blocklist
# $IPTABLES -F blocklist
# old_IFS=$IFS
# IFS=$'\n'
# for i in $(cat $INPUTF|egrep -v "^#|^$"); do
#     $IPTABLES -A blocklist -m iprange --dst-range $i -j DROP
# done
# IFS=$old_IFS

#Catena per il ban di uno specifico utente dall'accesso a determinati siti
#$IPTABLES -N ban_user
#$IPTABLES -F ban_user
#$IPTABLES -A ban_user -m owner --uid-owner $BAN_USER -j blocklist

#Catena per le connessioni gia' avviate (da mettere in fondo alle regole)
 $IPTABLES -N connessioni_avviate
 $IPTABLES -F connessioni_avviate
 $IPTABLES -A connessioni_avviate -m state --state ESTABLISHED,RELATED -j ACCEPT
# $IPTABLES -A connessioni_avviate -i $IFACE -m limit -j LOG --log-prefix "FW:Bad packet from ${IFACE}:"
 $IPTABLES -A connessioni_avviate -j DROP

#Catena per il ban di un determinato gruppo di utenti dalla rete.
 $IPTABLES -N ban_group
 $IPTABLES -F ban_group
 $IPTABLES -A ban_group -m owner --gid-owner $BAN_GROUP -j LOG --log-prefix "FW:BAN_GROUP:"
 $IPTABLES -A ban_group -m owner --gid-owner $BAN_GROUP -j DROP

#Catena per bloccare uno specifico ip
 $IPTABLES -N ban_ip
 $IPTABLES -F ban_ip
 for i in $BAN_IP; do
     if [ `echo $i|grep "-"|wc -l` -gt 0 ]; then
         $IPTABLES -A ban_ip -m iprange --src-range $i -j DROP
     else
         $IPTABLES -A ban_ip -s $i -j DROP
    fi
 done

#Catena per loggare uno specifico ip
 $IPTABLES -N log_ip
 $IPTABLES -F log_ip
 for i in $LOG_IP; do
     if [ `echo $i|grep "-"|wc -l` -gt 0 ]; then
         $IPTABLES -A log_ip -m iprange --src-range $i -m limit -j LOG --log-prefix "FW:LOG_IP: "
     else
         $IPTABLES -A log_ip -s $i -m limit -j LOG --log-prefix "FW:LOG_IP: "
     fi
 done

#Catena per il traffico ICMP in entrata
#ICMP (in entrata) Solo se fanno parte di connessioni preesistenti, cioe' si tratta di una risposta ad un
#pacchetto inviato dalla nostra rete
 $IPTABLES -N icmp_in
 $IPTABLES -F icmp_in
 $IPTABLES -A icmp_in -p icmp --icmp-type time-exceeded -j ACCEPT
 $IPTABLES -A icmp_in -p icmp --icmp-type destination-unreachable -j ACCEPT
#protezione dai PING-FLOOD
 $IPTABLES -A icmp_in -p icmp --icmp-type ping -m limit --limit 1/s -j ACCEPT
 $IPTABLES -A icmp_in -p icmp -j LOG --log-prefix "FW:Bad ICMP traffic:"

#Protezione dai SYN-FLOOD
# $IPTABLES -N syn_flood
# $IPTABLES -F syn_flood
# $IPTABLES -A syn_flood -p tcp --syn -m limit --limit 1/s --limit-burst 4 -j ACCEPT
# $IPTABLES -A syn_flood -p tcp --syn -j DROP

#Catena per il traffico ICMP in uscita
#ICMP (in uscita) Tutti gli icmp
 $IPTABLES -N icmp_out
 $IPTABLES -F icmp_out
 $IPTABLES -A icmp_out -o $IFACE -p icmp -j ACCEPT

#Catena per il DNS query
#DNS (client -> server) Vengono abilitate le query in uscita ai DNS servers
 $IPTABLES -N dns_query
 $IPTABLES -F dns_query
 $IPTABLES -A dns_query -o $IFACE -p udp -s $NAMESERVER_1 --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT
 $IPTABLES -A dns_query -o $IFACE -p udp -s $NAMESERVER_2 --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per SSH in entrata
#SSH (in entrata) In entrata abilitato il traffico per la porta $SSH_PORT
#Limtati i pacchetti RST FIN e SYN a 1/second
 $IPTABLES -N ssh_in
 $IPTABLES -F ssh_in
 $IPTABLES -A ssh_in -i $IFACE -m limit --limit 1/second -p tcp --tcp-flags ALL RST --dport $SSH_PORT -j ACCEPT
 $IPTABLES -A ssh_in -i $IFACE -m limit --limit 1/second -p tcp --tcp-flags ALL FIN --dport $SSH_PORT -j ACCEPT
 $IPTABLES -A ssh_in -i $IFACE -m limit --limit 1/second -p tcp --tcp-flags ALL SYN --dport $SSH_PORT -j ACCEPT
 $IPTABLES -A ssh_in -i $IFACE -p tcp --dport $SSH_PORT -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per SSH in uscita abilita le connessioni ssh alla porta $SSH_PORT e a quella di default (22)
 $IPTABLES -N ssh_out
 $IPTABLES -F ssh_out
 $IPTABLES -A ssh_out -o $IFACE -p tcp --dport $SSH_PORT -m state --state NEW,ESTABLISHED -j ACCEPT 
# $IPTABLES -A ssh_out -o $IFACE -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per il traffico HTTP e HTTPS in uscita
 $IPTABLES -N http_out
 $IPTABLES -F http_out
 $IPTABLES -A http_out -o $IFACE -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
 $IPTABLES -A http_out -o $IFACE -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per SAMBA in entrata
 $IPTABLES -N samba_in
 $IPTABLES -F samba_in
 $IPTABLES -A samba_in -i $IFACE -p udp --dport 137 -m state --state NEW,ESTABLISHED -j ACCEPT
 $IPTABLES -A samba_in -i $IFACE -p udp --dport 138 -m state --state NEW,ESTABLISHED -j ACCEPT
 $IPTABLES -A samba_in -i $IFACE -p tcp --dport 139 -m state --state NEW,ESTABLISHED -j ACCEPT
 $IPTABLES -A samba_in -i $IFACE -p tcp --dport 445 -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per FTP in entrata
 $IPTABLES -N ftp_in
 $IPTABLES -F ftp_in
 $IPTABLES -A ftp_in -i $IFACE -p tcp --dport 21 -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per RSYNC in entrata
 $IPTABLES -N rsync_in
 $IPTABLES -F rsync_in
 $IPTABLES -A rsync_in -i $IFACE -p tcp --dport 873 -m state --state NEW,ESTABLISHED -j ACCEPT
 
#Catena per BITTORRENT in entrata
 $IPTABLES -N bittorrent_in
 $IPTABLES -F bittorrent_in
 $IPTABLES -A bittorrent_in -i $IFACE -p tcp --dport $BITTORRENT_PORTS -m state --state NEW,ESTABLISHED -j ACCEPT

#Catena per TRANSMISSION in entrata
 $IPTABLES -N transmission_in
 $IPTABLES -F transmission_in
 $IPTABLES -A transmission_in -i $IFACE -p tcp --dport $TRANSMISSION_PORT -m state --state NEW,ESTABLISHED -j ACCEPT

##########################################################################
#Definisco la catene per intercettare i portscan
##########################################################################
#Catena per loggare i portscan
 $IPTABLES -N portscan
 $IPTABLES -F portscan
 
 #NMAP-XMAS
 $IPTABLES -A portscan -p tcp --tcp-flags ALL FIN,URG,PSH -m limit --limit 5/minute -j LOG --log-level alert --log-prefix "FW:SCAN:NMAP-XMAS:"
 $IPTABLES -A portscan -p tcp --tcp-flags ALL FIN,URG,PSH -j DROP
 
 #XMAS
 $IPTABLES -A portscan -p tcp --tcp-flags ALL ALL -m limit --limit 5/minute -j LOG --log-level 1 --log-prefix "FW:SCAN:XMAS:"
 $IPTABLES -A portscan -p tcp --tcp-flags ALL ALL -j DROP

 #XMAS-PSH
 $IPTABLES -A portscan -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -m limit --limit 5/minute -j LOG --log-level 1 --log-prefix "FW:SCAN:XMAS-PSH:"
 $IPTABLES -A portscan -p tcp --tcp-flags ALL SYN,RST,ACK,FIN,URG -j DROP

 #NULL_SCAN
 $IPTABLES -A portscan -p tcp --tcp-flags ALL NONE -m limit --limit 5/minute -j LOG --log-level 1 --log-prefix "FW:SCAN:NULL_SCAN:"
 $IPTABLES -A portscan -p tcp --tcp-flags ALL NONE -j DROP

 #SYN/RST
 $IPTABLES -A portscan -p tcp --tcp-flags SYN,RST SYN,RST -m limit --limit 5/minute -j LOG --log-level 5 --log-prefix "FW:SCAN:SYN/RST:"
 $IPTABLES -A portscan -p tcp --tcp-flags SYN,RST SYN,RST -j DROP

 #SYN/FIN
 $IPTABLES -A portscan -p tcp --tcp-flags SYN,FIN SYN,FIN -m limit --limit 5/minute -j LOG --log-level 5 --log-prefix "FW:SCAN:SYN/FIN:"
 $IPTABLES -A portscan -p tcp --tcp-flags SYN,FIN SYN,FIN -j DROP

##########################################################################
#Variabili SYS-CTL
##########################################################################
#Abilita o disabilita l'IP FORWARDING
#echo "1" > /proc/sys/net/ipv4/ip_forward
/bin/echo "0" > /proc/sys/net/ipv4/ip_forward

#DYNAMIC ADDRESSING (utile per il forwarding)
#/bin/echo "1" > /proc/sys/net/ipv4/ip_dynaddr

#Disabilita l'IP Spoofing
/bin/echo "1" > /proc/sys/net/ipv4/conf/all/rp_filter

#Non rispondere ai PING
#/bin/echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_all

#Non rispondere agli ICMP BROADCAST (attacchi smurf)
/bin/echo "1" > /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts

#Disabilita l'accettazione dei REDIRECT
/bin/echo "0" > /proc/sys/net/ipv4/conf/all/accept_redirects
/bin/echo "0" > /proc/sys/net/ipv4/conf/all/secure_redirects

#Protezione verso i messaggi di errore ICMP malformati
/bin/echo "1" > /proc/sys/net/ipv4/icmp_ignore_bogus_error_responses

#Disabilita i pacchetti source routed (previene dal guardare attraverso il NAT)
/bin/echo "0" > /proc/sys/net/ipv4/conf/all/accept_source_route

#Abilita LOG_MARTIANS (effettua il log dei pacchetti strani)
/bin/echo "1" > /proc/sys/net/ipv4/conf/all/log_martians

#Abilita il  REVERSE PATH FILTERING
for i in /proc/sys/net/ipv4/conf/*; do
  /bin/echo "1" > $i/rp_filter
done

##########################################################################
#Applico le catene a INPUT, OUTPUT e FORWARD
#Scarto i pacchetti INVALID
##########################################################################
#Applico le catene a INPUT
  $IPTABLES -A INPUT -j portscan
  $IPTABLES -A INPUT -m state --state INVALID -j DROP
  $IPTABLES -A INPUT -j log_ip
  $IPTABLES -A INPUT -j ban_ip
  $IPTABLES -A INPUT -j icmp_in
  $IPTABLES -A INPUT -i lo -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT
  input
  $IPTABLES -A INPUT -j connessioni_avviate

#Applico le catene a OUTPUT
#  $IPTABLES -A OUTPUT -m state --state INVALID -j DROP
  $IPTABLES -A OUTPUT -d 127.0.0.1 -j ACCEPT
  output

#Applico le catene a FORWARD
  $IPTABLES -A FORWARD -m state --state INVALID -j DROP
  $IPTABLES -A FORWARD -o lo -s 127.0.0.1 -d 127.0.0.1 -j ACCEPT
  forward
  $IPTABLES -A FORWARD -j connessioni_avviate

Grazie per la risposta, ma credo che il tuo script vada ben oltre il semplice scopo del mio

Magari puoi trarne qualcosa. Comunque è meno complicato di come sembra.