Moxa DA-685-LX [43/76] Ethernet bridging for private networks on the same subnet

DA-685 Linux Managing Communications

3-25

Interface eth1 and device tap0 both connect to the bridging interface, and the virtual device tun sits on top

of tap0. This ensures that all traffic coming to this bridge from internal networks connected to interface eth1

write to the TAP/TUN device that the OpenVPN program monitors. Once the OpenVPN program detects traffic

on the virtual device, it sends the traffic to its peer.

10. To create an indirect connection to Host B from Host A, you need to add the following routing item:

# route add –net 192.168.4.0 netmask 255.255.255.0 dev eth0

To create an indirect connection to Host A from Host B, you need to add the following routing item:

# route add –net 192.168.2.0 netmask 255.255.255.0 dev eth0

Now ping Host B from Host A by typing:

# ping 192.168.4.174

A successful ping indicates that you have created a VPN system that only allows authorized users from one

internal network to access users at the remote site. For this system, all data is transmitted by UDP packets on

port 5000 between OpenVPN peers.

11. To shut down OpenVPN programs, type the command:

# killall -TERM openvpn

Ethernet Bridging for Private Networks on the Same Subnet

1. Set up four machines, as shown in the following diagram.

Destination Gateway Genmsk Flags Metric Ref Use Iface

192.168.5.0 0.0.0.0 255.255.255.0 U 0 0 0 eth2

192.168.4.0 0.0.0.0 255.255.255.0 U 0 0 0 br0

192.168.3.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0

192.168.30.0 0.0.0.0 255.255.255.0 U 0 0 0 eth3

192.168.8.0 0.0.0.0 255.255.255.0 U 0 0 0 br0