AdminSysGNULinux

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{{tag>Brouillon Réseau iptables Sécurité Script}}

= Exemples de script init iptables

Note : ** iptables est remplacé maintenant par [[nftables_un_remplacant_d_iptables|nftables]] **

<code bash>
#!/bin/bash

. $(dirname "$0")/lib/common.sh

dieIfNotRoot

IPTABLES=/sbin/iptables
pf=$(getPlateformBasename $HOSTNAME)



### DEBUT config ### 

INTERFACE=eth0
VLAN='172\.16\.12\.'
REGEX_MACHINE='qua.*1|ftp1|gdp1'

### FIN config ###




check()
{	# Verif si $INTERFACE est dans le bon VLAN 
	/sbin/ifconfig $INTERFACE |sed -n -e '2p'|tr -s ' ' ':'| cut -d':' -f4 |grep -e "$VLAN" >/dev/null
	if [ $? -ne 0 ]
	then
		echo "ERREUR. L'interface $INTERFACE n'est pas dans le VLAN $(echo $VLAN| sed -e 's!\\.!\.!g')"
		exit 10
	fi

	# iptables doit etre demarre
	/etc/init.d/iptables status >/dev/null
	if [ $? -ne 0 ]
	then
		echo "ERREUR. Le service iptables n'est pas demarre"
		exit 11
	fi
}

flush()
{
	## On flush $IPTABLES.
	$IPTABLES -F
	## On supprime toutes les chaines utilisateurs.
	$IPTABLES -X

	# Regle par defaut (on autorise tout)
	$IPTABLES -P INPUT ACCEPT
	$IPTABLES -P OUTPUT ACCEPT
}

filter()
{
	# On whitelist toutes les machines de prod
	$IPTABLES -N WL_PROD
	for ip in $(grep -v -e '^#' /etc/hosts |egrep -i -e "$REGEX_MACHINE" |awk '{print $1}')
	do
		$IPTABLES -A INPUT -i $INTERFACE -s $ip -j WL_PROD
	done
	$IPTABLES -A WL_PROD -j ACCEPT

	# On autorise tous les packets de retour (quand la connexion est initiee depuis ce serveur)
	$IPTABLES -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

	# Par defaut aucun accees en interne hors des machines explicitement autorisees
	$IPTABLES -A INPUT -i $INTERFACE -s $(echo $VLAN |tr -d '\' |sed -e 's!$!0/24!') -j REJECT
}


case $1 in

	'start'|'restart')
	check
	if [ $? -eq 0 ]
	then
		flush 
		filter
	else
		echo "ERREUR check"
		exit $?
	fi
	;;

	'stop')
	flush
	;;

	*) 
	echo "usage: $0 start|stop|restart"
	;;

esac
</code>

<code bash>
#!/bin/bash

set -e

PATH=$PATH:/sbin
SERVERDNS=$(cat /etc/resolv.conf  |grep -e '^nameserver' |awk '{print $2}')
INTERFACE_OPEN=eth0
INTERFACE_SAFE=eth1
VLAN_OPEN='192\.168\.1\.'
VLAN_SAFE='10\.0\.2'
IPSERVER=$(ifconfig eth0 |grep -e 'inet adr:' |tr -s ' ' ':' |cut -f 4 -d':')
IP_ZABBIX_SERVER="172.16.110.3"

/sbin/ifconfig $INTERFACE_OPEN |sed -n -e '2p' |tr -s ' ' ':' | cut -d':' -f4 |grep -e "$VLAN_OPEN"
if [ $? -ne 0 ]
then
        echo "ERREUR. L'INTERFACE_OPEN eth0 n'est pas dans le VLAN $(echo $VLAN_OPEN| sed -e 's!\\.!\.!g')"
        exit 1
fi

/sbin/ifconfig $VLAN_SAFE |sed -n -e '2p'|tr -s ' ' ':'| cut -d':' -f4 |grep -e "$VLAN_SAFE"
if [ $? -ne 0 ]
then
        echo "ERREUR. L'INTERFACE_OPEN eth0 n'est pas dans le VLAN $(echo $VLAN_SAFE| sed -e 's!\\.!\.!g')"
        exit 2
fi



/etc/init.d/iptables status
if [ $? -ne 0 ]
then
        echo "ERREUR. Le service iptables n'est pas démarré"
        exit 3
fi

## On flush iptables.
iptables -F
## On supprime toutes les chaînes utilisateurs.
iptables -X
 
## On drop tout le trafic entrant.
iptables -P INPUT DROP
## On drop tout le trafic sortant.
iptables -P OUTPUT DROP
## On drop le forward.
iptables -P FORWARD DROP
 
## Permettre à une connexion ouverte de recevoir du trafic en entrée.
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
## Permettre à une connexion ouverte de recevoir du trafic en sortie.
# SSH, NTP etc...
iptables -A OUTPUT -m state ! --state INVALID -j ACCEPT
 
## On accepte la boucle locale en entrée.
iptables -I INPUT -i lo -j ACCEPT

# Open bar sur eth1
iptables -I INPUT -i $INTERFACE_SAFE -j ACCEPT

# DNS ==> IDEM POUR UDP
iptables -A OUTPUT -o $INTERFACE_OPEN -d $SERVERDNS -p udp --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o $INTERFACE_OPEN -d $SERVERDNS -p tcp --dport 53 -m state --state NEW,ESTABLISHED -j ACCEPT
#iptables -A INPUT  -i $INTERFACE_OPEN -p tcp --dport 1024:65535 --sport 53 -m state --state ESTABLISHED -j ACCEPT


# SERVER SSH
iptables -A INPUT -i $INTERFACE_OPEN -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT

# SERVER Agent Zabbix
iptables -A INPUT -i $INTERFACE_OPEN -s $IP_ZABBIX_SERVER -p tcp --dport 10050 -m state --state NEW,ESTABLISHED -j ACCEPT


# On restreint des ping http://www.oregontechsupport.com/articles/icmp.txt ?
# ou Ping dans tous les sens
iptables -A INPUT  -i $INTERFACE_OPEN -p icmp -j ACCEPT
iptables -A OUTPUT -i $INTERFACE_OPEN -p icmp -j ACCEPT

case $HOSTNAME in
    *web*)
        echo "Machine WEB"
	# SERVER HTTP/HTTPS
	iptables -A INPUT -i $INTERFACE_OPEN -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
	iptables -A INPUT -i $INTERFACE_OPEN -p tcp --dport 443 -m state --state NEW,ESTABLISHED -j ACCEPT
	# SERVER NFS
	#iptables -A INPUT -i $INTERFACE_OPEN -p tcp -s dev-ci1 --dport 2049 -m state --state NEW,ESTABLISHED -j ACCEPT
	#iptables -A INPUT -i $INTERFACE_OPEN -p udp -s dev-ci1 --dport 2049 -m state --state NEW,ESTABLISHED -j ACCEPT
    ;;

    *app*)
        echo "Machine APP"
	### 
	iptables -A INPUT -i $INTERFACE_OPEN -s qua-web3 -p tcp --dport 9960 -m state --state NEW,ESTABLISHED -j ACCEPT
    ;;

    *db*)
        echo "Machine DB"
	# SERVER Postgres
	iptables -A INPUT -i $INTERFACE_OPEN -s qua-app3 -p tcp --dport 5432 -m state --state NEW,ESTABLISHED -j ACCEPT
    ;;

esac

</code>



''/usr/share/doc/openvpn/examples/sample-config-files/firewall.sh''
<code bash>
#!/bin/sh

# A Sample OpenVPN-aware firewall.

# eth0 is connected to the internet.
# eth1 is connected to a private subnet.

# Change this subnet to correspond to your private
# ethernet subnet.  Home will use HOME_NET/24 and
# Office will use OFFICE_NET/24.
PRIVATE=10.0.0.0/24

# Loopback address
LOOP=127.0.0.1

# Delete old iptables rules
# and temporarily block all traffic.
iptables -P OUTPUT DROP
iptables -P INPUT DROP
iptables -P FORWARD DROP
iptables -F

# Set default policies
iptables -P OUTPUT ACCEPT
iptables -P INPUT DROP
iptables -P FORWARD DROP

# Prevent external packets from using loopback addr
iptables -A INPUT -i eth0 -s $LOOP -j DROP
iptables -A FORWARD -i eth0 -s $LOOP -j DROP
iptables -A INPUT -i eth0 -d $LOOP -j DROP
iptables -A FORWARD -i eth0 -d $LOOP -j DROP

# Anything coming from the Internet should have a real Internet address
iptables -A FORWARD -i eth0 -s 192.168.0.0/16 -j DROP
iptables -A FORWARD -i eth0 -s 172.16.0.0/12 -j DROP
iptables -A FORWARD -i eth0 -s 10.0.0.0/8 -j DROP
iptables -A INPUT -i eth0 -s 192.168.0.0/16 -j DROP
iptables -A INPUT -i eth0 -s 172.16.0.0/12 -j DROP
iptables -A INPUT -i eth0 -s 10.0.0.0/8 -j DROP

# Block outgoing NetBios (if you have windows machines running
# on the private subnet).  This will not affect any NetBios
# traffic that flows over the VPN tunnel, but it will stop
# local windows machines from broadcasting themselves to
# the internet.
iptables -A FORWARD -p tcp --sport 137:139 -o eth0 -j DROP
iptables -A FORWARD -p udp --sport 137:139 -o eth0 -j DROP
iptables -A OUTPUT -p tcp --sport 137:139 -o eth0 -j DROP
iptables -A OUTPUT -p udp --sport 137:139 -o eth0 -j DROP

# Check source address validity on packets going out to internet
iptables -A FORWARD -s ! $PRIVATE -i eth1 -j DROP

# Allow local loopback
iptables -A INPUT -s $LOOP -j ACCEPT
iptables -A INPUT -d $LOOP -j ACCEPT

# Allow incoming pings (can be disabled)
iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT

# Allow services such as www and ssh (can be disabled)
iptables -A INPUT -p tcp --dport http -j ACCEPT
iptables -A INPUT -p tcp --dport ssh -j ACCEPT

# Allow incoming OpenVPN packets
# Duplicate the line below for each
# OpenVPN tunnel, changing --dport n
# to match the OpenVPN UDP port.
#
# In OpenVPN, the port number is
# controlled by the --port n option.
# If you put this option in the config
# file, you can remove the leading '--'
#
# If you taking the stateful firewall
# approach (see the OpenVPN HOWTO),
# then comment out the line below.

iptables -A INPUT -p udp --dport 1194 -j ACCEPT

# Allow packets from TUN/TAP devices.
# When OpenVPN is run in a secure mode,
# it will authenticate packets prior
# to their arriving on a tun or tap
# interface.  Therefore, it is not
# necessary to add any filters here,
# unless you want to restrict the
# type of packets which can flow over
# the tunnel.

iptables -A INPUT -i tun+ -j ACCEPT
iptables -A FORWARD -i tun+ -j ACCEPT
iptables -A INPUT -i tap+ -j ACCEPT
iptables -A FORWARD -i tap+ -j ACCEPT

# Allow packets from private subnets
iptables -A INPUT -i eth1 -j ACCEPT
iptables -A FORWARD -i eth1 -j ACCEPT

# Keep state of connections from local machine and private subnets
iptables -A OUTPUT -m state --state NEW -o eth0 -j ACCEPT
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
iptables -A FORWARD -m state --state NEW -o eth0 -j ACCEPT
iptables -A FORWARD -m state --state ESTABLISHED,RELATED -j ACCEPT

# Masquerade local subnet
iptables -t nat -A POSTROUTING -s $PRIVATE -o eth0 -j MASQUERADE
</code>


---------

Source : http://www.linuxjournal.com/content/server-hardening?page=0,1

<code bash>

# make sure forwarding is off and clear everything
# also turn off ipv6 cause if you don't need it 
# turn it off
sysctl net.ipv6.conf.all.disable_ipv6=1
sysctl net.ipv4.ip_forward=0
iptables -F
iptables --flush
iptables -t nat --flush
iptables -t mangle --flush
iptables --delete-chain
iptables -t nat --delete-chain
iptables -t mangle --delete-chain


#make the default -drop everything
iptables --policy INPUT DROP
iptables --policy OUTPUT ACCEPT
iptables --policy FORWARD DROP


#allow all in loopback
iptables -A INPUT -i lo -j ACCEPT

#allow related
iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

#allow ssh
iptables -A INPUT -m tcp -p tcp --dport 22 -j ACCEPT

iptables -A INPUT -p tcp -m state --state NEW -m multiport --dports ssh,http,https -j ACCEPT


iptables -A INPUT -i eth0 -s 192.168.1.0/24 -p tcp -m state --state NEW -m multiport --dports http,https

</code>