$ sudo echo 1 >/proc/sys/net/ipv4/ip_forward
bash: /proc/sys/net/ipv4/ip_forward: Permission denied
then I try to get write privilege, also failed.
$ sudo chmod a+wx /proc/sys/net/ipv4/ip_forward
chmod: changing permissions of `/proc/sys/net/ipv4/ip_forward': Operation not permitted
what is wrong?
sudo