Passing VPN Traffic to another interface.

kimmyp · 05-10-2015, 11:47 AM

Hi Guys

I have a PPTP Server setup,I followed the instruction here https://help.ubuntu.com/community/PPTPServer
I have 2 NICs on this machine, on eth0 I am connected to my WAN side which allows for the
PPTP clients to dial in.The other interface connects to a switch of an internal network.

I followed the instruction here to have traffic routed between my 2 interfaces http://ubuntuforums.org/showthread.php?t=1905048

My problem is that the VPN clients when connected are not able to access any of the machines on the internal network,connected on eth1.

Please let me know how to achieve this please.

From VPN client

Code:

 Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    0.0.0.0         0.0.0.0         0.0.0.0         U     0      0        0 ppp0
    10.0.3.0        0.0.0.0         255.255.255.0   U     9      0        0 wlan0
    192.168.0.189   0.0.0.0         255.255.255.255 UH    0      0        0 ppp0

From Server

Code:

    Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
    192.168.0.190   0.0.0.0         255.255.255.255 UH    0      0        0 ppp0
    192.168.5.0     0.0.0.0         255.255.255.0   U     0      0        0 eth1
    192.168.99.0    192.168.5.9     255.255.255.0   UG    0      0        0 eth1
    192.168.0.0     0.0.0.0         255.255.255.0   U     0      0        0 eth0
    0.0.0.0         192.168.0.200   0.0.0.0         UG    100    0        0 eth0

It is almost as if the packet does not know how to come back to the client.

Please assist me

Thanks
DD

eantoranz · 05-10-2015, 11:32 PM

Ok... no experience with PPTP but let's try.

On the server, what is the output of these commands?

Code:

ip link show
ip addr show
ip route show
iptables -L -nv
iptables -t nat -L -nv
sysctl net.ipv4.ip_forward

then, on one gnu/linux client, both before and after connecting to the server, what is the output of these commands:

Code:

ip link show
ip addr show
ip route show

lsalab · 05-11-2015, 03:12 PM

I had a similar issue once and it turned out to be a missing route in the client configuration.

Maybe you server configuration is OK, but you need to add a route in your pptp clients to reach your LAN through the VPN.