Bridge (br0) has an IP address, but my LAN (eth2) doesnt?!

mkanet

I know this is a very basic question; but I can't even find any information on this via google searches. I realize that bridge interfaces can have IPs. However...

What confuses me is that my my physical Ethernet LAN adapter doesn't have any IP's bound to it. Instead, that IP is bound to the bridge virtual interface.

So, when I see sample scripts like the one below; they require the name of the Interface and IP of the physical LAN adapter. I'm not sure what to put in there for the eth_ip value. It's not exactly true that it's IP's would be 192.168.1.1; since that's the IP used for the bridge interface.

I did notice that eth2 and br0 both have the same hardware mac address. Does that mean that I can say that my eth_ip has an IP address; even though technically, it doesn't have any IP address?

bridge-start.sh

# Define physical ethernet interface to be bridged
# with TAP interface(s) above.
eth="eth2"
eth_ip="192.168.1.1"
eth_netmask="255.255.255.0"
eth_broadcast="192.168.1.255"

Here's my ifconfig list:

/opt/home/admin # ifconfig
br0       Link encap:Ethernet  HWaddr 11:DE:21:C1:37:25
          inet addr:192.168.1.1  Bcast:192.168.1.255  Mask:255.255.255.0
          inet6 addr: 2611:9:1380:60:11cf:30ff:feb8:2725/64 Scope:Global
          inet6 addr: 2611:9:1380:60:11cf:30ff:feb8:2725/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:15467 errors:0 dropped:0 overruns:0 frame:0
          TX packets:16119 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:2950678 (2.8 MiB)  TX bytes:8610765 (8.2 MiB)

eth2      Link encap:Ethernet  HWaddr 11:DE:21:C1:37:25
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:31171 errors:0 dropped:0 overruns:0 frame:0
          TX packets:49784 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:4527738 (4.3 MiB)  TX bytes:54182003 (51.6 MiB)
          Interrupt:3

eth3      Link encap:Ethernet  HWaddr 20:CF:30:B8:27:24
          inet addr:150.52.60.250  Bcast:150.52.60.255  Mask:255.255.254.0
          inet6 addr: 4001:218:1256:16:1fff:a2ef:12c0:5340/128 Scope:Global
          inet6 addr: fe80::401e:1ecf:abc2:2724/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:120700 errors:0 dropped:0 overruns:0 frame:0
          TX packets:28859 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:58565085 (55.8 MiB)  TX bytes:4023840 (3.8 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 MULTICAST  MTU:16436  Metric:1
          RX packets:460 errors:0 dropped:0 overruns:0 frame:0
          TX packets:460 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:187652 (183.2 KiB)  TX bytes:187652 (183.2 KiB)

ra0       Link encap:Ethernet  HWaddr 22:CF:30:B8:27:20
          UP BROADCAST RUNNING 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:4

tap0      Link encap:Ethernet  HWaddr 12:94:7F:28:F1:72
          inet addr:10.249.84.1  Bcast:10.249.84.255  Mask:255.255.255.0
          inet6 addr: fe80::1094:7fff:fe28:f172/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:4 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100
          RX bytes:0 (0.0 B)  TX bytes:408 (408.0 B)

mkanet

Also, towards the end of my bridge-start script, it shows:

ifconfig $eth 0.0.0.0 promisc up

which translates to:

ifconfig eth2 0.0.0.0 promisc up

So, I'm not sure if a command like that would even work on the Ethernet interface that doesnt have an IP bound to it.

Anyway, hopefully someone will see this and shed some light on this.

janjust

this question is about Linux bridges, not about OpenVPN; in bridged mode the associated ethN device AND the associated tapX device should not have their own IP addresses. In your config your tap0 device has a separate IP . Use

brctl show br0

to show the existing status of the bridge.

mkanet

Hi,

I'm trying to get bridge mode work properly under OpenVPN (so netbios traffic can pass through between TAP0 <---> LAN . Is there a better place to ask my questions about about OpenVPN/Bridging? It very hard for me to find someone who is willing to help me with this.

My OpenVPN/Linux image came with br0 +eth2 already bridged. So, when I boot up Linux, br0 is already created with eth2 (LAN) added to it. I just need to know what I need to do for in order for my openVPN client (connected via tap0) to see netbios traffic from my remote LAN. Currently, my openVPN client "can" connect to other devices on my LAN; but doesn't see netbios traffic.

I tried my best to follow the below document. However, it looks like it was meant for people who don't have a bridge setup yet.
http://openvpn.net/index.php/open-source/documentation/miscellaneous/76-ethernet-bridging.html

Thanks in advance,
MKANET