Dear all,
I'm trying to setup a Raspberry Pi2 as a special kind of bridge+router,
but am getting stuck (basically way before the difficult stuff starts)
with just basic bridging already. I've tried figuring this out on my
own and with searching through all stuff on the Internet, but still am
no step closer to understanding the cause of my problems (even though I
don't thing I'm an idiot), so this is basically a cry for help ...
So, the basics of my setup:
Client <----> RPI2 <----> LAN
The RPI2 has an extra eth1 via USB to which the Windows-7 client is
connected, while the rest of the network is connected through eth0 of
the RPI2. The LAN contains a server that hands out DHCP addresses.
The RPI2 is running the latest Raspbian Jessie (Linux raspberrypi
4.1.13-v7+ #826 SMP PREEMPT Fri Nov 13 20:19:03 GMT 2015 armv7l
GNU/Linux).
I created the bridge through the /etc/network/interfaces config file:
auto lo eth1 br0
iface lo inet loopback
iface eth0 inet manual
iface eth1 inet manual
iface br0 inet dhcp
bridge_fd 0
bridge_maxwait 0
bridge_stp off
bridge_ports eth0 eth1
The fd, maxwait and stp bridge settings were actually added after
checking the Internet for the problems I was hitting. I've also tried
executing explicit brctl commands for the same, but that didn't change
anything ... No ebtables or iptables rules applied yet, since I first
wanted to test basic bridging.
With this setup, when I attach my Windows-7 client to eth1 of the RPI
and ensure the client has a static IP in the same range as the LAN, then
everything seems to work fine. I can ping hosts on the LAN from the
client and vice-versa, BUT ...
If I tell the client to use DHCP, then it (most of the time) doesn't
get an IP address. I added a rule to just log events in the FORWARD
chain of ebtables' filter table, which (filtered on ports 67 and 68)
shows:
Dec 27 10:35:54 raspberrypi kernel: [73804.793870] LOG_FORWARD IN=eth1
OUT=eth0 MAC source = 00:26:2d:c6:df:50 MAC dest = ff:ff:ff:ff:ff:ff
proto = 0x0800 IP SRC=0.0.0.0 IP DST=255.255.255.255, IP tos=0x00, IP
proto=17 SPT=68 DPT=67
Dec 27 10:35:54 raspberrypi kernel: [73804.794508] LOG_FORWARD IN=eth0
OUT=eth1 MAC source = 00:e0:4c:e8:42:30 MAC dest = ff:ff:ff:ff:ff:ff
proto = 0x0800 IP SRC=192.168.21.1 IP DST=255.255.255.255, IP tos=0x10,
IP proto=17 SPT=67 DPT=68
Dec 27 10:35:54 raspberrypi kernel: [73804.799762] LOG_FORWARD IN=eth0
OUT=eth1 MAC source = 00:e0:4c:e8:42:30 MAC dest = ff:ff:ff:ff:ff:ff
proto = 0x0800 IP SRC=192.168.21.1 IP DST=255.255.255.255, IP tos=0x10,
IP proto=17 SPT=67 DPT=68
Dec 27 10:35:54 raspberrypi kernel: [73804.801009] LOG_FORWARD IN=eth1
OUT=eth0 MAC source = 00:26:2d:c6:df:50 MAC dest = ff:ff:ff:ff:ff:ff
proto = 0x0800 IP SRC=0.0.0.0 IP DST=255.255.255.255, IP tos=0x00, IP
proto=17 SPT=68 DPT=67
Dec 27 10:35:54 raspberrypi kernel: [73804.809660] LOG_FORWARD IN=eth0
OUT=eth1 MAC source = 00:e0:4c:e8:42:30 MAC dest = ff:ff:ff:ff:ff:ff
proto = 0x0800 IP SRC=192.168.21.1 IP DST=255.255.255.255, IP tos=0x10,
IP proto=17 SPT=67 DPT=68
Dec 27 10:35:55 raspberrypi kernel: [73805.917988] LOG_FORWARD IN=eth1
OUT=eth0 MAC source = 00:26:2d:c6:df:50 MAC dest = ff:ff:ff:ff:ff:ff
proto = 0x0800 IP SRC=0.0.0.0 IP DST=255.255.255.255, IP tos=0x00, IP
proto=17 SPT=68 DPT=67
Dec 27 10:35:55 raspberrypi kernel: [73805.924720] LOG_FORWARD IN=eth0
OUT=eth1 MAC source = 00:e0:4c:e8:42:3
0 MAC dest = ff:ff:ff:ff:ff:ff proto = 0x0800 IP SRC=192.168.21.1 IP
DST=255.255.255.255, IP tos=0x10, IP proto=17 SPT=67 DPT=68
So, I would conclude from this (correct me if I'm wrong) that the
server (192.168.21.1) is receiving the request for a DHCP address and
even responds back, but for some reason this response either never
reaches the Windows 7 machine or it refuses to use it.
Now, yesterday, for an extensive period, the problem was gone: I could
attach the client, get an IP, detach it, attach it again and get the
same IP again. Then this morning, with nothing changed, not even the
power taken off from any of the involved devices (apart from the client
which was put to sleep while detached from the network), it came back to
not getting an IP at all ...
So, any clue, tips or whatever that could help me in figuring out the
root cause here?
Much thanks in advance and happy hollidays to all!
K.
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