Difference between revisions of "Firewall VPN"
 
(11 intermediate revisions by the same user not shown)
Line 2: Line 2:
  
  
−
=What is a VPN=
+
=What is a VPN?=
  
−
As a quick reminder, you can use a VPN for 3 things:
+
See [[VPN#Reminder:_What_is_a_.E2.80.9CVPN.E2.80.9D.3F|What is a VPN?]]
−
* Mask your source IP @
 
  
−
[[File:VPN change ip address 1.png|none|VPN change ip address (1)]]
 
  
−
[[File:VPN change ip address 2.png|none|VPN change ip address (2)]]
 
  
 +
=VPN firewall=
 +
 +
Adjust the following to your own port, network ID and protocol:
 +
 +
<syntaxhighlight lang="bash">
 +
IPTABLES=`which iptables`
 +
IP6TABLES=`which ip6tables`
 +
 +
# usage:  vpn <vpn interface> <vpn port> <vpn protocol> <local interface> <remote LAN IPv4 [optional]> <remote LAN IPv6 [optional]>
 +
#    ex  vpn tun0 8080 udp eth0
 +
#    ex  vpn tun0 8080 udp eth0 "192.168.15.0/24"
 +
#    ex  vpn tun0 8080 udp eth0 "192.168.15.0/24" "2001:41d0:8:9318::/64"
 +
function vpn { 
 +
    INT_VPN=$1
 +
    VPN_PORT=$2
 +
    VPN_PROTOCOL=$3
 +
    INT_LOCAL=$4
 +
    VPN_LAN_IPv4=$5
 +
    VPN_LAN_IPv6=$6
  
−
* Secure communication through the VPN server
+
    echo "Setting up VPN rules"
  
−
[[File:VPN client to client.png|none|VPN client to client]]
+
    #####
 +
    # Allow VPN connections through $INT_VPN
 +
    # Hint: if you do not accept all RELATED,ESTABLISHED connections then you must allow the source port
 +
    #####
 +
    echo "Init VPN"
 +
    $IPTABLES -A INPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN incoming" -j ACCEPT
 +
    $IPTABLES -A OUTPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT
 +
    $IPTABLES -A OUTPUT -p $VPN_PROTOCOL --sport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT
  
 +
    $IP6TABLES -A INPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN incoming" -j ACCEPT
 +
    $IP6TABLES -A OUTPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT
 +
    $IP6TABLES -A OUTPUT -p $VPN_PROTOCOL --sport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT
  
−
* Access remote LAN
+
    # Allow VPN packets type INPUT,OUTPUT,FORWARD
 +
    $IPTABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
 +
    $IPTABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
 +
    $IPTABLES -A FORWARD -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
  
−
[[File:VPN to lan.png|none|VPN to LAN]]
+
    $IP6TABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
 +
    $IP6TABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
 +
    $IP6TABLES -A FORWARD -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
  
  
−
Of course you can combine some / all of these usages.
+
    ######
 +
    # Allow forwarding
 +
    ######
 +
    echo "Enable forwarding form $INT_VPN /to/ $INT_LOCAL"
 +
    $IPTABLES -A FORWARD -i $INT_VPN -o $INT_LOCAL -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT
 +
    $IPTABLES -A FORWARD -i $INT_LOCAL -o $INT_VPN -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT
  
 +
    $IP6TABLES -A FORWARD -i $INT_VPN -o $INT_LOCAL -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT
 +
    $IP6TABLES -A FORWARD -i $INT_LOCAL -o $INT_VPN -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT
  
 +
    # Allow packet to go/from the VPN network to the LAN
 +
    $IPTABLES -t nat -A POSTROUTING -o $INT_LOCAL -m comment --comment "Forward between interfaces" -j MASQUERADE
 +
    $IP6TABLES -t nat -A POSTROUTING -o $INT_LOCAL -m comment --comment "Forward between interfaces" -j MASQUERADE
  
 +
    ######
 +
    # Allow local LAN / remote LAN communication through VPN
 +
    ######
 +
    if [[ ! -z "$VPN_LAN_IPv4" ]]
 +
    then
 +
    echo "VPN LAN IPv4: $VPN_LAN_IPv4"
 +
        # Allow packets to be send to VPN
 +
        $IPTABLES -A OUTPUT -d $VPN_LAN_IPv4 -m comment --comment "VPN LAN: $VPN_LAN_IPv4" -j ACCEPT
 +
        $IPTABLES -A FORWARD -s $VPN_LAN_IPv4 -m comment --comment "VPN LAN: $VPN_LAN_IPv4" -j ACCEPT
  
 +
        log_progress_msg "Allow VPN client to client communication"
 +
        # Allow VPN client <-> client communication
 +
        $IPTABLES -A INPUT -s $VPN_LAN_IPv4 -d $VPN_LAN_IPv4 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
 +
        $IPTABLES -A OUTPUT -s $VPN_LAN_IPv4 -d $VPN_LAN_IPv4 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
 +
    fi
 +
    if [[ ! -z "$VPN_LAN_IPv6" ]]
 +
    then
 +
    echo "VPN LAN IPv6: $VPN_LAN_IPv6"
 +
        # Allow packets to be send to VPN
 +
        $IP6TABLES -A OUTPUT -d $VPN_LAN_IPv6 -m comment --comment "VPN LAN: $VPN_LAN_IPv6" -j ACCEPT
 +
        $IP6TABLES -A FORWARD -s $VPN_LAN_IPv6 -m comment --comment "VPN LAN: $VPN_LAN_IPv6" -j ACCEPT
  
−
=VPN firewall=
+
        log_progress_msg "Allow VPN client to client communication"
 +
        # Allow VPN client <-> client communication
 +
        $IP6TABLES -A INPUT -s $VPN_LAN_IPv6 -d $VPN_LAN_IPv6 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
 +
        $IP6TABLES -A OUTPUT -s $VPN_LAN_IPv6 -d $VPN_LAN_IPv6 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
 +
    fi
 +
 
 +
 
 +
    ####### Add route(s) to remote network(s)
 +
    # You must add a new route for each network you'd like to access through the VPN server!
 +
    # The VPN server must be able to reach the remote network! (otherwise it cannot acts as a GW !)
 +
    # route add -net <network>/<mask> gw <VPN_SERVER_ETH_IP>
 +
    #
 +
    # !! This information should be pushed by the server !!
 +
    # If not you can either add it manually over here (= in Iptables) or in the OpenVPN client conf.
 +
    #######
 +
    #echo "      ... add VPN route between VPN LAN and current location"
 +
    #route add -net 192.168.12.0/24 gw 192.168.1.45
 +
 
 +
}
 +
</syntaxhighlight>
  
−
Adjust the following to your own port, network ID and protocol:
 
  
−
<syntaxhighlight lang="bash">
 
−
IPTABLES=`which iptables`
 
  
−
INT_ETH=eth0
+
==Sysctl==
−
IP_LAN_ETH=`/sbin/ifconfig $INT_ETH | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}'`
 
  
−
INT_VPN=tun0
+
You must enable FORWARDING somewhere else:
−
VPN_PORT="8080"
 
−
VPN_PROTOCOL="udp"
 
−
LAN_ADDRESS_VPN="172.16.60.0/24"
 
  
−
echo -e " "
+
<syntaxhighlight lang="bash">
−
echo -e "------------------------"
+
vim /etc/sysctl.conf
−
echo -e " VPN configuration"
+
</syntaxhighlight>
−
echo -e "------------------------"
 
  
−
echo " "
 
−
echo -e "# VPN interface  : $INT_VPN"
 
−
echo -e "# VPN IP @      : $LAN_ADDRESS_VPN"
 
−
echo -e "# VPN port      : $VPN_PORT"
 
−
echo -e "# VPN protocol  : $VPN_PROTOCOL"
 
−
echo -e "-------------------------------------- "
 
  
−
# Allow devices communication $ETH0 <--> tun0
 
−
$IPTABLES -t nat -A POSTROUTING -s $LAN_ADDRESS_VPN -o $INT_ETH -j MASQUERADE
 
−
$IPTABLES -A FORWARD -s $LAN_ADDRESS_VPN -j ACCEPT
 
  
−
echo -e " ... Allow VPN connections"
+
<syntaxhighlight lang="apache">
−
$IPTABLES -A INPUT -p $VPN_PROTOCOL --dport $VPN_PORT -j ACCEPT
+
# Uncomment the next line to enable packet forwarding for IPv4
−
$IPTABLES -A OUTPUT -p tcp --dport $VPN_PORT -j ACCEPT
+
net.ipv4.ip_forward=1
  
−
echo -e " ... Allow everything to go through VPN - all INPUT,OUTPUT,FORWARD"
 
−
$IPTABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -j ACCEPT
 
−
$IPTABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -j ACCEPT
 
−
$IPTABLES -A FORWARD -o $INT_VPN -m state ! --state INVALID -j ACCEPT
 
  
−
echo -e " ... Allow VPN network communication (required for client <> client comm.)"
+
# Uncomment the next line to enable packet forwarding for IPv6
−
$IPTABLES -A INPUT -s $LAN_ADDRESS_VPN -d $LAN_ADDRESS_VPN -j ACCEPT
+
#  Enabling this option disables Stateless Address Autoconfiguration
−
$IPTABLES -A OUTPUT -s $LAN_ADDRESS_VPN -d $LAN_ADDRESS_VPN -j ACCEPT
+
#  based on Router Advertisements for this host
 +
net.ipv6.conf.all.forwarding=1
 
</syntaxhighlight>
 
</syntaxhighlight>

Latest revision as of 21:36, 10 September 2015


What is a VPN?

See What is a VPN?


VPN firewall

Adjust the following to your own port, network ID and protocol: 

IPTABLES=`which iptables`
IP6TABLES=`which ip6tables`

# usage:   vpn <vpn interface> <vpn port> <vpn protocol> <local interface> <remote LAN IPv4 [optional]> <remote LAN IPv6 [optional]> 
#     ex   vpn tun0 8080 udp eth0
#     ex   vpn tun0 8080 udp eth0 "192.168.15.0/24"
#     ex   vpn tun0 8080 udp eth0 "192.168.15.0/24" "2001:41d0:8:9318::/64"
function vpn {   
    INT_VPN=$1
    VPN_PORT=$2
    VPN_PROTOCOL=$3 
    INT_LOCAL=$4
    VPN_LAN_IPv4=$5
    VPN_LAN_IPv6=$6

    echo "Setting up VPN rules" 

    #####
    # Allow VPN connections through $INT_VPN
    # Hint: if you do not accept all RELATED,ESTABLISHED connections then you must allow the source port
    #####
    echo "Init VPN"
    $IPTABLES -A INPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN incoming" -j ACCEPT
    $IPTABLES -A OUTPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT
    $IPTABLES -A OUTPUT -p $VPN_PROTOCOL --sport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT

    $IP6TABLES -A INPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN incoming" -j ACCEPT
    $IP6TABLES -A OUTPUT -p $VPN_PROTOCOL --dport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT
    $IP6TABLES -A OUTPUT -p $VPN_PROTOCOL --sport $VPN_PORT -m comment --comment "VPN outgoing" -j ACCEPT

    # Allow VPN packets type INPUT,OUTPUT,FORWARD
    $IPTABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
    $IPTABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
    $IPTABLES -A FORWARD -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT

    $IP6TABLES -A INPUT -i $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
    $IP6TABLES -A OUTPUT -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT
    $IP6TABLES -A FORWARD -o $INT_VPN -m state ! --state INVALID -m comment --comment "Invalid VPN packet" -j ACCEPT


    ######
    # Allow forwarding
    ######
    echo "Enable forwarding form $INT_VPN /to/ $INT_LOCAL"
    $IPTABLES -A FORWARD -i $INT_VPN -o $INT_LOCAL -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT
    $IPTABLES -A FORWARD -i $INT_LOCAL -o $INT_VPN -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT

    $IP6TABLES -A FORWARD -i $INT_VPN -o $INT_LOCAL -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT
    $IP6TABLES -A FORWARD -i $INT_LOCAL -o $INT_VPN -m comment --comment "Forwarding $INT_LOCAL <> VPN" -j ACCEPT

    # Allow packet to go/from the VPN network to the LAN
    $IPTABLES -t nat -A POSTROUTING -o $INT_LOCAL -m comment --comment "Forward between interfaces" -j MASQUERADE
    $IP6TABLES -t nat -A POSTROUTING -o $INT_LOCAL -m comment --comment "Forward between interfaces" -j MASQUERADE

    ######
    # Allow local LAN / remote LAN communication through VPN
    ######
    if [[ ! -z "$VPN_LAN_IPv4" ]]
    then
    	echo "VPN LAN IPv4: $VPN_LAN_IPv4"
        # Allow packets to be send to VPN
        $IPTABLES -A OUTPUT -d $VPN_LAN_IPv4 -m comment --comment "VPN LAN: $VPN_LAN_IPv4" -j ACCEPT
        $IPTABLES -A FORWARD -s $VPN_LAN_IPv4 -m comment --comment "VPN LAN: $VPN_LAN_IPv4" -j ACCEPT

        log_progress_msg "Allow VPN client to client communication"
        # Allow VPN client <-> client communication
        $IPTABLES -A INPUT -s $VPN_LAN_IPv4 -d $VPN_LAN_IPv4 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
        $IPTABLES -A OUTPUT -s $VPN_LAN_IPv4 -d $VPN_LAN_IPv4 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
    fi 
    if [[ ! -z "$VPN_LAN_IPv6" ]]
    then
    	echo "VPN LAN IPv6: $VPN_LAN_IPv6"
        # Allow packets to be send to VPN
        $IP6TABLES -A OUTPUT -d $VPN_LAN_IPv6 -m comment --comment "VPN LAN: $VPN_LAN_IPv6" -j ACCEPT
        $IP6TABLES -A FORWARD -s $VPN_LAN_IPv6 -m comment --comment "VPN LAN: $VPN_LAN_IPv6" -j ACCEPT

        log_progress_msg "Allow VPN client to client communication"
        # Allow VPN client <-> client communication
        $IP6TABLES -A INPUT -s $VPN_LAN_IPv6 -d $VPN_LAN_IPv6 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
        $IP6TABLES -A OUTPUT -s $VPN_LAN_IPv6 -d $VPN_LAN_IPv6 -m state ! --state INVALID -m comment --comment "VPN client-to-client" -j ACCEPT
    fi 


    ####### Add route(s) to remote network(s)
    # You must add a new route for each network you'd like to access through the VPN server!
    # The VPN server must be able to reach the remote network! (otherwise it cannot acts as a GW !)
    # route add -net <network>/<mask> gw <VPN_SERVER_ETH_IP>
    #
    # !! This information should be pushed by the server !! 
    # If not you can either add it manually over here (= in Iptables) or in the OpenVPN client conf.
    #######
    #echo "      ... add VPN route between VPN LAN and current location"
    #route add -net 192.168.12.0/24 gw 192.168.1.45

}


Sysctl

You must enable FORWARDING somewhere else: 

vim /etc/sysctl.conf


# Uncomment the next line to enable packet forwarding for IPv4
net.ipv4.ip_forward=1


# Uncomment the next line to enable packet forwarding for IPv6
#  Enabling this option disables Stateless Address Autoconfiguration
#  based on Router Advertisements for this host
net.ipv6.conf.all.forwarding=1
Retrieved from "http://www.daxiongmao.eu/wiki/index.php?title=Firewall_VPN&oldid=2502"