Linux Ethernet Bridging - Apr 2007 - [Bridge] bridging bluetooth bnep devices with kernel 2.6.6-*

2.6.6 got too picky about multiple interfaces with the same
address. This patch has been already integrated for later releases.

diff -Nru a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
--- a/net/bridge/br_fdb.c	Mon May 10 13:45:50 2004
+++ b/net/bridge/br_fdb.c	Mon May 10 13:45:50 2004
@@ -277,18 +277,18 @@
 		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
 			/* attempt to update an entry for a local interface */
 			if (unlikely(fdb->is_local)) {
-				if (is_local) 
-					printk(KERN_INFO "%s: attempt to add"
-					       " interface with same source address.\n",
-					       source->dev->name);
-				else if (net_ratelimit()) 
-					printk(KERN_WARNING "%s: received packet with "
-					       " own address as source address\n",
-					       source->dev->name);
-				ret = -EEXIST;
+				/* it is okay to have multiple ports with same 
+				 * address, just don't allow to be spoofed.
+				 */
+				if (!is_local) {
+					if (net_ratelimit()) 
+						printk(KERN_WARNING "%s: received packet with "
+						       " own address as source address\n",
+						       source->dev->name);
+					ret = -EEXIST;
+				}
 				goto out;
 			}
-
 
 			if (likely(!fdb->is_static || is_local)) {
 				/* move to end of age list */

It seems that switching from 2.4.x to 2.6.x
caused the bridge of more than a bnep (Bluetooth)
device to stop to work.

Details on this kind of bridging at:
http://www.cs.ucla.edu/~cclljj/interest/notes/bluez/pand_bridge_nap.html

Note that the MAC address of all these devices is the same,
as they belong to the same bluetooth device.

# ifconfig bnep0
bnep0     Link encap:Ethernet  HWaddr 00:02:72:80:1B:3B
          inet6 addr: fe80::202:72ff:fe80:1b3b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:537 errors:0 dropped:0 overruns:0 frame:0
          TX packets:138 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:69267 (67.6 KiB)  TX bytes:24779 (24.1 KiB)

# ifconfig bnep1
bnep1     Link encap:Ethernet  HWaddr 00:02:72:80:1B:3B
          inet6 addr: fe80::202:72ff:fe80:1b3b/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:14 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:5094 (4.9 KiB)  TX bytes:356 (356.0 b)

What I did is:

# brctl addbr pan0
# ifconfig pan0 192.168.111.1
# brctl setfd pan0 0
# brctl stp pan0 disable

# brctl addif pan0 bnep0
# ifconfig bnep0 0.0.0.0

And the first bluetooth link works fine,
but when I try to add a second link I get:

# brctl addif pan0 bnep1
can't add bnep1 to bridge pan0: File exists
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

if I try to remove bnep1:
# brctl delif pan0 bnep1
device bnep1 is not a slave of pan0

With kernel 2.4.x instead everything works.
Any suggestion?

Regards,

Diego.