Search the Community

HOW TO FORWARD PORTS TO YOUR DEVICES WITH IPTABLES You need to create a basic DNAT on your router. Remember that the router GUI forwards ports from the WAN to LAN. When connected to the VPN you must forward ports from TUN to LAN. Therefore, it is imperative that you do NOT forward ports in the GUI of the router. Assuming that: destIP is the IP address of the destination deviceport is the port you wish to forward to that devicetun1 is the tun interface of your router (please check! on some routers it can be tun0, on Tomato it can be tun11)you need to forward both TCP and UDP packetsyou need to add the following rules. Please note that the following rules do NOT replace your already existing rules, you just have to add them. iptables -I FORWARD -i tun1 -p udp -d destIP --dport port -j ACCEPT iptables -I FORWARD -i tun1 -p tcp -d destIP --dport port -j ACCEPT iptables -t nat -I PREROUTING -i tun1 -p tcp --dport port -j DNAT --to-destination destIP iptables -t nat -I PREROUTING -i tun1 -p udp --dport port -j DNAT --to-destination destIP Note: if your router firmware iptables supports the multiport module you can use --match option to make your rules set more compact. Please see here, thanks to Mikeyy https://airvpn.org/topic/14991-asuswrt-merlin-multiple-ports/?do=findComment&comment=31221 Kind regards

Hello, I'm a new airvpn user. I run Tomato USB on my router and have iptables setup on the router to limit the WAN ip addresses one of my LAN clients can talk with. The idea is if my my VPN client drops, no more data will go OUT from this particular client through my public IP. The router should still forward all WAN traffic IN to this client but the client won't respond with any data. I had this working well with my previous VPN providor and I think the iptables rules below are what's needed for airvpn. But I've had 2 disconnections in about 2 days since I joined airvpn and am wondering if there's another airvpn IP I need to include in my list below to have a stable connection. If I drop again, I'll be sure to copy the log and post in the forums for help. But maybe there's something with my iptables that needs tweaking; tia. # iptables on router with tomato usb firmware # for LAN client [lan client mac address] only allow outgoing traffic to WAN airvpn.org and vpn server iptables -I FORWARD 1 -m mac --mac-source [lan client mac address] -d [airvpn.org ip address] -j ACCEPT iptables -I FORWARD 2 -m mac --mac-source [lan client mac address] -d [airvpn server ip address] -j ACCEPT iptables -I FORWARD 3 -m mac --mac-source [lan client mac address] -j DROP

EDITED ON 21 Aug 12 EDITED ON 24 Nov 12: added important note for some Linux users, see bottom of message EDITED ON 02 Jun 15: please refer to https://airvpn.org/faq/software_lock for a more advanced set of rules WARNING: this guide assumes that you have no IPv6 connectivity. If you have, you should block outgoing IPv6 packets while connected to the VPN with "ip6tables". Please see https://airvpn.org/faq/software_lock Hello! You can use iptables, a very powerful packet filtering and NAT program (probably one of the most powerful, if not the most powerful of all). iptables is already included in all official Ubuntu distros and most Linux distros, anyway if you don't have it just install it with aptitude. Adding the following simple rules will prevent leaks in case of [accidental] VPN disconnection. In this example, it is assumed that your network interface is eth+ (change it as appropriate; for example, you might have wlan0 for a WiFi connection). a.b.c.d is the entry-IP address of the Air server you connect to. You can find out the address simply looking at the line "remote" of your air.ovpn configuration file. In case of doubts, just ask us. Some of the following rules might be redundant if you have already chains. Assumptions: you are in a 192.168.0.0/16 network and your router is a DHCP server. You have a a physical network interface named eth*. The tun adapter is tun* and the loopback interface is lo. iptables -A INPUT -i lo -j ACCEPT iptables -A OUTPUT -o lo -j ACCEPT #allow loopback access iptables -A OUTPUT -d 255.255.255.255 -j ACCEPT #make sure you can communicate with any DHCP server iptables -A INPUT -s 255.255.255.255 -j ACCEPT #make sure you can communicate with any DHCP server iptables -A INPUT -s 192.168.0.0/16 -d 192.168.0.0/16 -j ACCEPT #make sure that you can communicate within your own network iptables -A OUTPUT -s 192.168.0.0/16 -d 192.168.0.0/16 -j ACCEPT iptables -A FORWARD -i eth+ -o tun+ -j ACCEPT iptables -A FORWARD -i tun+ -o eth+ -j ACCEPT # make sure that eth+ and tun+ can communicate iptables -t nat -A POSTROUTING -o tun+ -j MASQUERADE # in the POSTROUTING chain of the NAT table, map the tun+ interface outgoing packet IP address, cease examining rules and let the header be modified, so that we don't have to worry about ports or any other issue - please check this rule with care if you have already a NAT table in your chain iptables -A OUTPUT -o eth+ ! -d a.b.c.d -j DROP # if destination for outgoing packet on eth+ is NOT a.b.c.d, drop the packet, so that nothing leaks if VPN disconnects When you add the above rules, take care about pre-existing rules, if you have already some tables, and always perform a test to verify that the subsequent behavior is what you expect: when you disconnect from the VPN, all outgoing traffic should be blocked, except for a reconnection to an Air server. In order to block specific programs only, some more sophisticated usage of iptables is needed, and you will also need to know which ports those programs use. See "man iptables" for all the features and how to make the above rules persistent or not according to your needs. Warning: the following applies ONLY for Linux users who don't have resolvconf installed and don't use up & down OpenVPN directives with update-resolv-conf script In this case, your system has no way to process the DNS push from our servers. Therefore your system will just tunnel the DNS queries with destination the DNS IP address specified in the "nameserver" lines of the /etc/resolv.conf file. But if your first nameserver is your router IP, the queries will be sent to your router which in turn will send them out unencrypted. Solution is straightforward: edit the /etc/resolv.conf file and add the following line at the top (just an example, of course you can use any of your favorite DNS, as long as it is NOT your router): nameserver 10.4.0.1 # in order to use AirVPN DNS nameserver 31.220.5.106 # in order to use OpenNIC DNS only if AirVPN DNS is unavailable Kind regards Original thread post: https://airvpn.org/topic/1713-win-mac-bsd-block-traffic-when-vpn-disconnects/page-2?do=findComment&comment=2010

Hello, This post is to everyone that have openvpn configured in a dd-wrt router and wants to block all connections through the ISP if the VPN connection fails, avoiding leaking our real ISP IP. I setup the connection to AIRVPN servers using the tutorial in https://airvpn.org/ddwrt and then insert following line to the firewall rules: "iptables -I FORWARD -i br0 -o vlan2 -j DROP" - br0 is the bridge with my lan ports & wireless - vlan2 is my WAN port connected to the modem ISP So if there is any connection starting from my lan or wifi to the wan port the firewall of the router blocks the connection. My firewall rules are like this: iptables -I FORWARD -i br0 -o tun0 -j ACCEPT iptables -I FORWARD -i tun0 -o br0 -j ACCEPT iptables -I FORWARD -i br0 -o vlan2 -j DROP iptables -I INPUT -i tun0 -j REJECT iptables -t nat -A POSTROUTING -o tun0 -j MASQUERADE [sTAFF EDIT] In case you apply Policy Based Routing, please see here as well: http://www.dd-wrt.com/phpBB2/viewtopic.php?p=777788 Check the interface names and make sure to enter the correct names (in your firmware the tun interface might be tun1 or tun0, etc.).