OpenVPN Support Forum

Posted: **Sat Jan 29, 2011 8:35 pm**

This is going to be a bit lengthy so, apologies in advance.

Background
I recently replaced my edge device (a Netgear WNR834Bv2 Running DDWRT v24 SP2 mini-VPN) with a Juniper SSG-5.
I'm now using the netgear as a glorified WAP and VPN termination point.

Problem
I am unable to establish a remote desktop session across the tunnel on my android phone using Remote RDP Enterprise, in the previous setup this worked flawlessly.
I am able to bring the tunnel up and ping across it to the destination addresses as well as receive DNS responses for the local LAN.

Configuration details
dcwanfw1 - Juniper SSG5 Firewall - 10.168.53.1
Routes

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IPv4 Dest-Routes for <trust-vr> (12 entries)
--------------------------------------------------------------------------------------
         ID          IP-Prefix      Interface         Gateway   P Pref    Mtr     Vsys
--------------------------------------------------------------------------------------
*       558          0.0.0.0/0         eth0/0         x.x.x.x   C    0      1     Root
*       605          0.0.0.0/0         eth0/2         x.x.x.x   C    0      1     Root
        160          0.0.0.0/0         eth0/2         x.x.x.x   S   20      1     Root
*         4         x.x.x.x/32         eth0/2         0.0.0.0   H    0      0     Root
*        65         x.x.x.x/19         eth0/0         0.0.0.0   C    0      0     Root
*       133    172.16.101.0/24        bgroup0     10.168.53.2   S   20      1     Root
*       126    172.16.100.0/24        bgroup0     10.168.53.3   S   20      1     Root
*         5     10.168.53.0/24        bgroup0         0.0.0.0   C    0      0     Root
*         6     10.168.53.1/32        bgroup0         0.0.0.0   H    0      0     Root
*        11   192.168.1.254/32         eth0/2         x.x.x.x   S   20      1     Root
*        66         x.x.x.x/32         eth0/0         0.0.0.0   H    0      0     Root
*         3         x.x.x.0/22         eth0/2         0.0.0.0   C    0      0     Root

Policy

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dcwanfw1-> get pol
Total regular policies 6, Default deny, Software based policy search, new policy enabled.
    ID From     To       Src-address  Dst-address  Service              Action State   ASTLCB
     1 Trust    TWC      Any          Any          ANY                  Permit enabled ---X-X
     2 Trust    AT&T     Any          Any          ANY                  Permit enabled ---X-X
     7 AT&T     Trust    Any          VIP(etherne~ HTTP                 Permit enabled ---X-X
                                                   OpenVPN
     6 AT&T     Trust    Any          Any          ANY                  Deny   enabled ---X-X
     8 TWC      Trust    Any          VIP(etherne~ HTTP                 Permit enabled ---X-X
                                                   OpenVPN
     5 TWC      Trust    Any          Any          ANY                  Deny   enabled ---X-X

Trust is 10.168.53.0/24

===========================================================================

dcwap2 - Netgear WNR834Bv2 with DDWRT (OpenVPN Server) - 10.168.53.3
Routes

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Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
172.16.100.0    *               255.255.255.0   U     0      0        0 tun0
10.168.53.0     *               255.255.255.0   U     0      0        0 br0
169.254.0.0     *               255.255.0.0     U     0      0        0 br0
127.0.0.0       *               255.0.0.0       U     0      0        0 lo
default         dcwanfw1.gaming 0.0.0.0         UG    0      0        0 br0

IPTables

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 iptables -L -v
Chain INPUT (policy ACCEPT 2901 packets, 317K bytes)
 pkts bytes target     prot opt in     out     source               destination
  124 10862 ACCEPT     udp  --  any    any     anywhere             anywhere            udp dpt:1194

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination
    6   360 ACCEPT     0    --  tun0   br0     172.16.100.0/24      anywhere
    0     0 ACCEPT     0    --  br0    tun0    anywhere             172.16.100.0/24

OpenVPN - Server - Config

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server 172.16.100.0 255.255.255.0
dev tun0
mode server
proto udp
port 1194
keepalive 15 60
daemon
verb 3
comp-lzo
client-to-client
tls-server
dh /tmp/openvpn/dh.pem
ca /tmp/openvpn/ca.crt
cert /tmp/openvpn/cert.pem
key /tmp/openvpn/key.pem
push "route 10.168.53.0 255.255.255.0"
push "dhcp-option WINS 10.168.53.40"
push "dhcp-option DNS 10.168.53.40"
push "dhcp-option DNS 10.168.53.41"
push "dhcp-option DOMAIN gaming.local"
management localhost 5001

Troubleshooting

I have a feeling whatever is wrong is wrong on the OpenVPN Box, maybe not necessarily with OpenVPN, but some type of security setting, this might do better over at the DD-WRT forum but I figured lets try my luck here.

Routing seems to be good since i can ping LAN to VPN Client and VPN Client to LAN.
I can also bring up SSH to various servers on the LAN through the tunnel using ConnectBot which satisfies routing.

I've tried the following DD-WRT settings:

Switched to Gateway mode
Switched to Routed Mode
Specified Self (10.168.53.3) as DMZ
Disabled SPI Firewall

Posted: **Mon Jan 31, 2011 7:38 am**

hi there,

did you try setup the openvpn on another device (a pc maybe..)?
if you use scp to copy files ,is it working?

good day,

michael.

Posted: **Tue Feb 01, 2011 6:23 am**

Thanks for the reply, I sorted this out this afternoon after I had some more time to play with it.

There was an asynchronous route and the Juniper SSG5 was getting the SYN-ACK without first seeing a SYN and therefore putting a stop to the connection. Only affected TCP and only to addresses other than the default LAN gateway (where I tested SSH) due to the stateful nature of the device.

Once I had some more time this afternoon I tried to SSH from my Droid to other linux boxes on the network and found that I couldn't.

Paying closer attention to the trace routes I saw that the traceroute from the android was not being default routed when it came out of the br0 interface from the DDWRT appliance. A quick static route fixed that issue.

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