Hi,all I did a test on kernel3.16 rc6: root@qemu1:~# echo 1 > /proc/sys/net/ipv6/conf/all/forwarding root@qemu1:~# echo 1 > /proc/sys/net/ipv4/conf/all/forwarding root@qemu1:~# ip netns list root@qemu1:~# ip netns add fib1 root@qemu1:~# ip netns exec fib1 bash root@qemu1:~# cat /proc/sys/net/ipv6/conf/all/forwarding 0 root@qemu1:~# cat /proc/sys/net/ipv4/conf/all/forwarding 1 The behavior of ipv4 and ipv6 is very inconsistent. I checked the kernel source code. I found that from this patch [ipv6: fix bad free of addrconf_init_net], the above difference appeared. Since a net namespace is independent to another. That is, there is no any relationship between the net namespaces. So the behavior of ipv4 is not correct. Based on this patch [ipv6: fix bad free of addrconf_init_net], I made a new patch to fix this problem on ipv4. Any reply is appreciated. Zhu Yanjun