How to bind OpenVPN to one network interface?

Maxor91

Hello all,

I have a server with two separate network interfaces running through the same router eth0 (10.1.1.35) and eth1 (10.1.1.36). I have tried to bind my OpenVPN client to eth1 by including the following line in my .conf file:

local 10.1.1.36

ip route shows that eth0 is still the default route, which is what I want, however it seems that ALL of my network traffic is going through the VPN Service instead of just the traffic assigned to eth1. I've tested this by running the VPN service and doing a traceroute,which shows the traffic going through the VPN Service.

Anyone have any suggestions on how I can fix this issue? I'm trying to set it up so I have some services (SSH, Web Server) running on eth0, and other services running on eth1 through the VPN.

I appreciate any help! Let me know if any more information is needed. Thanks,

Max

maikcat

hi there,

can you please post more info about your setup?

f.e, openvpn config file,output of: ifconfig,netstat -nr,ip route show,iptables -L -t nat -v

regards

Michael.

Maxor91

Yes, here is the info you asked for.

openvpn.conf:

client
dev tun
proto udp
local 10.1.1.36
remote vpn.sanfrancisco.witopia.net 1194
resolv-retry infinite
persist-key
persist-tun
ca /etc/openvpn/ca.crt
cert /etc/openvpn/CN0027XXXX.crt
key /etc/openvpn/CN0027XXXX.key
cipher BF-CBC
comp-lzo
verb 3

ifconfig:

eth0      Link encap:Ethernet  HWaddr 00:c0:49:fa:20:e7  
          inet addr:10.1.1.35  Bcast:10.1.1.255  Mask:255.255.255.0
          inet6 addr: fe80::2c0:49ff:fefa:20e7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2486702 errors:0 dropped:0 overruns:0 frame:0
          TX packets:3177002 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:443869674 (423.3 MiB)  TX bytes:836398442 (797.6 MiB)
          Interrupt:22 Base address:0xc00 

eth1      Link encap:Ethernet  HWaddr 00:0c:f1:e2:16:c2  
          inet addr:10.1.1.36  Bcast:10.1.1.255  Mask:255.255.255.0
          inet6 addr: fe80::20c:f1ff:fee2:16c2/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:2367968 errors:0 dropped:0 overruns:0 frame:0
          TX packets:2137663 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:1256154932 (1.1 GiB)  TX bytes:970675793 (925.7 MiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:598735 errors:0 dropped:0 overruns:0 frame:0
          TX packets:598735 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:168249655 (160.4 MiB)  TX bytes:168249655 (160.4 MiB)

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
          inet addr:10.119.75.238  P-t-P:10.119.75.237  Mask:255.255.255.255
          UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1500  Metric:1
          RX packets:1349690 errors:0 dropped:0 overruns:0 frame:0
          TX packets:1522526 errors:0 dropped:109 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:777006939 (741.0 MiB)  TX bytes:192633288 (183.7 MiB)

netstat -nr:

Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
205.164.56.59   10.1.1.1        255.255.255.255 UGH       0 0          0 eth1
10.119.75.237   0.0.0.0         255.255.255.255 UH        0 0          0 tun0
10.119.72.1     10.119.75.237   255.255.255.255 UGH       0 0          0 tun0
10.1.1.0        0.0.0.0         255.255.255.0   U         0 0          0 eth1
10.1.1.0        0.0.0.0         255.255.255.0   U         0 0          0 eth0
0.0.0.0         10.119.75.237   128.0.0.0       UG        0 0          0 tun0
128.0.0.0       10.119.75.237   128.0.0.0       UG        0 0          0 tun0
0.0.0.0         10.1.1.1        0.0.0.0         UG        0 0          0 eth0

ip route show:

205.164.56.59 via 10.1.1.1 dev eth1 
10.119.75.237 dev tun0  proto kernel  scope link  src 10.119.75.238 
10.119.72.1 via 10.119.75.237 dev tun0 
10.1.1.0/24 dev eth1  proto kernel  scope link  src 10.1.1.36  metric 1 
10.1.1.0/24 dev eth0  proto kernel  scope link  src 10.1.1.35  metric 1 
0.0.0.0/1 via 10.119.75.237 dev tun0 
128.0.0.0/1 via 10.119.75.237 dev tun0 
default via 10.1.1.1 dev eth0  proto static

iptables -L -t nat -v:

Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain POSTROUTING (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination         

Chain OUTPUT (policy ACCEPT 0 packets, 0 bytes)
 pkts bytes target     prot opt in     out     source               destination

Thanks for your help! Let me know if you need anything else. Getting this resolved would be really great.

Max

Maxor91

Oops, posted same message twice.

maikcat

can you please read this first..

http://kindlund.wordpress.com/2007/11/19/configuring-multiple-default-routes-in-linux/

Michael.

Maxor91

Well, that is exactly what I needed! Works perfectly. Thanks!

maikcat

glad to helped you out.

Regards,

Michael.