User`s manual

Moxa C Programmable RTU Controllers Managing Communications
4-22
Destination Gateway Genmsk Flags Metric Ref Use Iface
192.168.4.0 * 255.255.255.0 U 0 0 0 br0
192.168.2.0 * 255.255.255.0 U 0 0 0 br0
192.168.8.0 * 255.255.255.0 U 0 0 0 eth0
Interface eth1 is connected to the bridging interface br0, to which device tap0 also connects, whereas the
virtual device tun sits on top of tap0. This ensures that all traffic from internal networks connected to interface
eth1 that come to this bridge 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.
6. 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.
7. To shut down OpenVPN programs, type the command:
# killall -TERM openvpn
Setup 2: Ethernet Bridging for Private Networks on the Same Subnet
1. Set up four machines as shown in the following diagram:
2. The configuration procedure is almost the same as for the previous example. The only difference is that you
will need to comment out the parameter “up” in “/etc/openvpn/A-tap0-br.conf” and
“/etc/openvpn/B-tap0-br.conf”.