--- /etc/network/interfaces-----
auto lo
iface lo inet loopback

auto eth1
iface eth1 inet dhcp
--------------------------------

--- netstat -rn ----------------
Kernel IP routing table
Destination		Gateway			Genmask			Flags	MSS	Window	irtt	Iface
0.0.0.0			192.168.0.1		0.0.0.0			UG		0	0		0		eth1
10.8.0.0		10.8.0.2		255.255.255.0	UG		0	0		0		tun0
10.8.0.2		0.0.0.0			255.255.255.255	UH		0	0		0		tun0
192.168.0.0		0.0.0.0			255.255.255.0	U		0	0		0		eth1
-------------------------------

---ifconfig -a ----------------
eth0	Link encap:Ethernet HWaddr 00:21:70:ce:65:1d
		BROADCAST MULTICAST MTU:1500 Metric: 1
		RX packets:0 errors:0 dropped:0 overruns:0 frame:0
		TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
		collisions:0 txqueuelen:1000
		RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)
		Interrupt:17

eth1	Link encap:Ethernet HWaddr d8:eb:97:b7:23:ae
		inet addr:192.168.0.12 Bcast:192.168.0.255 Mask:255.255.255.0
		UP BROADCAST RUNNING MULTICAST MTU:1500 Metric: 1
		RX packets:646 errors:0 dropped:0 overruns:0 frame:0
		TX packets:52 errors:0 dropped:0 overruns:0 carrier:0
		collisions:0 txqueuelen:1000
		RX bytes:53265 (53.2 B)  TX bytes:4864 (4.8 KB)

lo		Link encap:Local Loopback
		inet addr:127.0.0.1 Mask:255.0.0.0
		UP LOOPBACK RUNNING MTU:65536 Metric: 1
		RX packets:0 errors:0 dropped:0 overruns:0 frame:0
		TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
		collisions:0 txqueuelen:0
		RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

tun0	Link encap:UNSPEC HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
		inet addr:10.8.0.1  P-t-P:10.8.0.2 Mask:255.255.255.255
		UP POINTOPOINT RUNNING NOARP MULTICAST MTU:1500 Metric:1
		RX packets:0 errors:0 dropped:0 overruns:0 frame:0
		TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
		collisions:0 txqueuelen:100
		RX bytes:0 (0.0 B)	TX bytes:0 (0.0 B)
-----------------------------