OpenVPN connects but no internet access

Question

I can't figure out why my openvpn connection is not working. It seems that it works fine on connection. I can connect to my server but once when I'm connected I can't use internet through vpn.

This is a VPS server running on Debian

Here is my openvpn server.conf file

port 1194

proto udp

dev tun

ca ca.crt
cert server.crt
key server.key  # This file should be kept secret

dh dh2048.pem

server 10.8.0.0 255.255.255.0

ifconfig-pool-persist ipp.txt

push "redirect-gateway def1"

push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"

keepalive 10 120

comp-lzo

user nobody
group nogroup

persist-key
persist-tun

status openvpn-status.log

log         openvpn.log

verb 6

mute 20

And here is my client.conf file

client

dev tun

proto udp

remote server_ip 1194

resolv-retry infinite

nobind

persist-key
persist-tun

ca ca.crt
cert client.crt
key client.key

ns-cert-type server

comp-lzo

verb 3

remote-cert-tls server

I've added firewall rules also to accept connection and route but strange thing is that some rules appear multiple times. Here is my iptables save file

# Generated by iptables-save v1.4.8 on Sun Dec 22 04:36:18 2013
*nat
:PREROUTING ACCEPT [53:9749]
:POSTROUTING ACCEPT [9:675]
:OUTPUT ACCEPT [9:675]
-A PREROUTING -d server_ip/32 -p udp -m udp --dport 53 -j REDIRECT --to-ports 1194 
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE 
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE 
-A POSTROUTING -s 10.8.0.0/24 -j SNAT --to-source server_ip 
-A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE 
COMMIT
# Completed on Sun Dec 22 04:36:18 2013
# Generated by iptables-save v1.4.8 on Sun Dec 22 04:36:18 2013
*filter
:INPUT ACCEPT [946:112417]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [824:172939]
-A INPUT -i tun0 -p tcp -m tcp --dport 1194 -j ACCEPT 
-A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT 
-A FORWARD -s 10.8.0.0/24 -j ACCEPT 
-A FORWARD -j REJECT --reject-with icmp-port-unreachable 
-A FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT 
-A FORWARD -s 10.8.0.0/24 -j ACCEPT 
-A FORWARD -j REJECT --reject-with icmp-port-unreachable 
-A FORWARD -i eth0 -o tun0 -m state --state RELATED,ESTABLISHED -j ACCEPT 
-A FORWARD -s 10.8.0.0/24 -o eth0 -j ACCEPT 
COMMIT
# Completed on Sun Dec 22 04:36:18 2013

I also checked /etc/sysctl.conf to make sure that

net.ipv4.ip_forward=1

I also have

net.ipv6.conf.all.forwarding=1

So I've tried OpenVPN connection on my linux pc and on Virtualbox XP and both have connection but none of them have access to internet once connected.

Strangest thing of all this is when I do traceroute it shows connection through VPN.

For example I do traceroute google.com

1 my ip from vpn connection
2 openvpn server ip
3 ...
4 ...
5 ... few hops between server to google
6 and finally google server ip

So traceroute shows that connection goes through vpn, and also when I ping, ping is increased to 100ms in difference when I'm not connected to vpn when ping is about 20ms.

But when I try to browse the internet with any program (firefox, chrome, iexplorer) I don't get anything. Nothing will load and connection times out.

It's not that my server is slow so pages won't load, speed test shows about 70mbit connection on server, and I have 6mbit connection.

And when I try to connect to other vpn like cloudnymous everything works fine. It's just something wrong on my openvpn setup.

EDIT: After all I thought I finally made it working, after messing around a lot of settings I finally can connect to my VPN and get internet from there.

Now I have one final problem. Since I'm on linux few programs doesn't work here and I use virtualbox with windows XP installation but when connected to vpn on virtualbox I can surf the internet. But no program can connect to the internet. Also my vpn connection is loosing internet from time to time, and it's not my internet or server connection because during that time when I loose internet over vpn I can still connect with putty over ssh to the server and do various things.

Answer 1

Make sure /etc/default/ufw on the server has DEFAULT_FORWARD_POLICY="ACCEPT" instead of "DROP" and then restart the firewall

sudo ufw disable
sudo ufw enable

Answer 2

Masquerading does not work on a VPS .. you must use iptables Source NAT instead:

iptables -t nat -A POSTROUTING -s 10.x.x.x/xx -j SNAT --to-source y.y.y.y

x.x.x.x/x is the VPN subnet - y.y.y.y is the IP address of your server output interface.

Answer 3

I had a similar problem where OpenVPN was working OK until I changed the router. I suspected the router firewall although I had opened the required ports. However, I looked at rc.local and saw that, when first configured, the iptables line had been set up with the actual IP address rather than the $MY_IP variable I expected like this:

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to 192.168.0.15

rather than:

iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -j SNAT --to $MY_IP

Problem was changing the router assigned a different IP to the server and I just made a reservation for the new IP and expected all to work.

If I had reserved the same IP for the server as before I could have saved a lot of head scratching.