Bug#760525: linux-image-3.14-2-amd64: routing fails
Package: linux-image-3.14-2-amd64
Version: 3.14.15-2
Severity: important
Routing fails when there are macvtaps attached and SNAT/DNAT is used for
routing with a tap device. (The routing being talked about concerns
between eth0's public IP address and tap0 which is not a macvtap device
on eth0.)
The first test of routing is simple
'Forwarding' is set on eth0, and on a tap device(which was created with
ip tuntap)
echo 1 >
/proc/sys/net/ipv4/conf/eth0/forwarding
(or sysctl -w net.ipv4.conf.eth0.forwarding=1)
echo 1 >
/proc/sys/net/ipv4/conf/tap0/forwarding
On the far end of tap0 (a VM), a station's IP address is being
SNAT/DNATted on this hypervisor's eth0
Here's the thing, I know it's a kernel issue because it never fails when
I do
echo 1 > /proc/sys/net/ipv4/conf/all/forwarding
echo 0 > /proc/sys/net/ipv4/conf/all/forwarding
echo 1 > /proc/sys/net/ipv4/conf/eth0/forwarding
echo 1 > /proc/sys/net/ipv4/conf/tap0/forwarding
right away after on clean boot (and having started the VM)
Don't be distracted by the VM and other things in the way.
Here is the condition why this fails,
-> Macvtap devices on eth0(there's about 3 or 4). When there are no
macvtap devices on eth0, routing doesn't need to be fixed using these
four commands..
Routing from the tap0 device which later gets natted with eth0 always
works but only after I issue these four commands.
I believe this is more an upstream issue so I'll be cloning this bugreport.
thanks
-Scott
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