How to only allow OpenVPN connections with IPtables ?

User-N@me · 05-23-2011, 01:42 PM

Hello, I'd like to configure IPtables to make sure I can only access the internet through an openvpn connection (so when the connection is down I have no way to access the internet but to connect to the vpn again).

I know how to do this with Firestarter (restrictive outgoing policy and I only allow the vpn server IPs) but Firestarter seems to be stupid : for some reason eth0 was changed to eth1 and Firestarter can't work properly anymore, even though that probably can be fixed with Firestarter I'm no more interested in this program and I'd better like to know how to apply the same policy using IPtables.

I've tried a few things already but it failed each time ... how can I effectively allow my computer to connect to the VPN while everything else is blocked ?

User-N@me · 05-23-2011, 04:39 PM

Code:

iptables -A INPUT -s xx.xxx.xx.xx -j ACCEPT
iptables -A OUTPUT -d xx.xxx.xx.xx -j ACCEPT
iptables -A INPUT -j DROP
iptables -A OUTPUT -j DROP

Why isn't this working ? What should I add ?

Edit, oops I forgot :

Code:

iptables -A INPUT -i tun+ -j ACCEPT
iptables -A OUTPUT -o tun+ -j ACCEPT

Silly me ...

User-N@me · 05-23-2011, 07:06 PM

Turns out the problem isn't solved, my current set of rules work when I activate them when I'm already connected to the VPN but it won't let me connect to the VPN if I load the rules at boot.

My rules :

Code:

# Generated by iptables-save v1.4.10 on Mon May 23 18:02:08 2011
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -i lo -j ACCEPT 
-A INPUT -i tun+ -j ACCEPT 
-A INPUT -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT 
-A INPUT -s xx.xxx.xx.xx -j ACCEPT 
-A INPUT -j DROP 
-A OUTPUT -o tun+ -j ACCEPT 
-A OUTPUT -d xx.xxx.xx.xx -j ACCEPT 
-A OUTPUT -j DROP 
COMMIT
# Completed on Mon May 23 18:02:08 2011

What should I change ?

User-N@me · 05-25-2011, 05:13 AM

*bump*