Trouble getting packets flowing with OpenVPN on Asus RT-N66U

tiagoespinha

Hi all, this is my first post but I'll jump straight into my problem.

Long story short, I have an ASUS RT-N66U running the modified Merlin firmware (the one which comes with OpenVPN) and I set it all up. I followed some tutorials on how to generate what keys and as of now, I manage to get my clients (using Android's OpenVPN Connect and Tunnelblick on OSX) to successfully authenticate and connect with the server. The issue is that no packets actually flow through the VPN.

Here's my setup (which is somewhat special):
FRITZ!BOX DSL Router/Modem (10.0.0.1) <----> (DMZ - 10.0.0.84) ASUS RT-N66U (192.168.1.1) <----> [My Network]

Now, here's my server's config.ovpn:

# Automatically generated configuration
daemon
server 10.8.0.0 255.255.255.0
proto udp
port 1194
dev tun21
comp-lzo adaptive
keepalive 15 60
verb 3
push "route 192.168.1.0 255.255.255.0"
push "dhcp-option DNS 192.168.1.1"
push "redirect-gateway def1"
tls-auth static.key 0
ca ca.crt
dh dh.pem
cert server.crt
key server.key
status-version 2
status status

# Custom Configuration

And my client's .ovpn file (with the sensitive parts omitted):

remote xxxxxxx
tls-client
dev tun
pull
<ca>
xxxxx
</ca>
<cert>
xxxxx
</cert>
<key>
xxxxx
</key>
key-direction 1
<tls-auth>
xxxxx
</tls-auth>

Pretty standard, right? I've tried it with both TAP and TUN and still no joy. I did notice something which might be useful info: when using OpenVPN Connect, I see several kBytes sent when the connection is active but the "received" counter sits at exactly 0 bytes and 0 packets. It's as if the server simply is completely unable to talk to the client.

If there is any more info needed to help me sort this out, I'll be happy to oblige!

Thanks in advance!

tiagoespinha

Oh, just another piece of data. This is the output of my netstat -nr (on OSX) before I connect (NB the IP addresses are 192.168.43.xxx because I'm using a mobile hotspot to try this out):

Internet:
Destination        Gateway            Flags        Refs      Use   Netif Expire
default            192.168.43.1       UGSc           54        0     en1
127                127.0.0.1          UCS             0        0     lo0
127.0.0.1          127.0.0.1          UH            318   249267     lo0
169.254            link#5             UCS             0        0     en1
192.168.43         link#5             UCS             2        0     en1
192.168.43.1       2:1a:11:fb:e4:c1   UHLWIir        55      109     en1   1187
192.168.43.212     127.0.0.1          UHS             1       25     lo0
192.168.43.255     ff:ff:ff:ff:ff:ff  UHLWbI          0       18     en1
192.168.56         link#8             UC              2        0 vboxnet
192.168.56.255     ff:ff:ff:ff:ff:ff  UHLWbI          0       15 vboxnet

This is what I get after I connect to the VPN (the xxx out address is my public IP address, on the FRITZ!BOX):

Internet:
Destination        Gateway            Flags        Refs      Use   Netif Expire
0/1                10.8.0.5           UGSc            3        0    tun0
default            192.168.43.1       UGSc           19        0     en1
10.8.0.1/32        10.8.0.5           UGSc            0        0    tun0
10.8.0.5           10.8.0.6           UHr            12        0    tun0
xxx.xxx.xxx.xxx/32  192.168.43.1       UGSc            1        0     en1
127                127.0.0.1          UCS             0        0     lo0
127.0.0.1          127.0.0.1          UH            318   249400     lo0
128.0/1            10.8.0.5           UGSc            5        0    tun0
169.254            link#5             UCS             0        0     en1
192.168.1          10.8.0.5           UGSc            1        0    tun0
192.168.43         link#5             UCS             2        0     en1
192.168.43.1       2:1a:11:fb:e4:c1   UHLWIir         3      135     en1   1163
192.168.43.212     127.0.0.1          UHS             1       25     lo0
192.168.43.255     ff:ff:ff:ff:ff:ff  UHLWbI          0       23     en1
192.168.56         link#8             UC              2        0 vboxnet
192.168.56.255     ff:ff:ff:ff:ff:ff  UHLWbI          0       16 vboxnet

And also, this is the tun interface I get:

tun0: flags=8851<UP,POINTOPOINT,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	inet 10.8.0.6 --> 10.8.0.5 netmask 0xffffffff 
	open (pid 11835)

tiagoespinha

Anyone? 😐 *Bump*

bencummins

I had the same thing, and it turned out to be a compression issue.

I am using Pfsense as the server side, and it defaulted to having compression (comp-lzo setting) off. Setting the compress to none in the client config on the asus router sorted this out for me. Obviously, if you have compression enabled, the setting being 'Enabled' works also.