Why can not change the file /proc/sys/net/ipv4/ip_forward?

Question

$ 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?

should use $ sudo bash -c "echo 1 >/proc/sys/net/ipv4/ip_forward" — Victor S, Aug 15 '13 at 14:43
related: [Redirect the output using `sudo`](http://askubuntu.com/q/20578/127745) — JonnyJD, Aug 26 '14 at 08:53
Possible duplicate of [When using sudo with redirection, I get 'permission denied'](http://askubuntu.com/questions/230476/when-using-sudo-with-redirection-i-get-permission-denied) — David Foerster, Feb 07 '16 at 19:10

devav2 · Answer 1 · 2012-09-22T05:52:22.367

9

You are trying to change the kernel values. Be sure of what you are doing.

Okay here is how you can change the value of ip_forward with root privilege (sudo -i)

First check the value of ip_forward using command: sysctl -a | grep ip_forward
Now using sysctl -w <parameter=value> you change the value of ip_forward:
- sysctl -w ip_forward=1
Make these changes to reflect in kernel using: sysctl -p
Do the first step once again to check the values.

I recommend you to go through the man page of sysctl

edited Sep 22 '12 at 05:52

answered Sep 22 '12 at 05:44

devav2

1

On newer installs it's `sysctl -w net.ipv4.ip_forward=1` with the full namespace – darryn.ten Jun 05 '17 at 13:40

score 1 · Answer 2 · edited Apr 07 '15 at 06:46

1

Edit file /etc/sysctl.conf and edit this section:

#net.ipv4.ip_forward = 0

to

net.ipv4.ip_forward = 1 (remove # sign)

then type command: sysctl -p
Last, reboot your system.

edited Apr 07 '15 at 06:46

bummi

answered Apr 07 '15 at 05:42

Bizax

score 0 · Answer 3 · answered Aug 18 '20 at 04:09

0

To change this kernel value in kernel version 4.4+ (Ubuntu 16.04+), you need to do the following:

sudo sysctl -w net.ipv4.ip_forward=1

answered Aug 18 '20 at 04:09

rouble

score -1 · Answer 4 · edited Feb 07 '16 at 19:15

-1

Terminal:

sudo nano /proc/sys/net/ipv4 ip_forward

after change it, save with CTRL + O and exit with CTRL + X

edited Feb 07 '16 at 19:15

Dimitri Podborski

answered Feb 07 '16 at 18:42

anon

-1 Text editors are a bad way to edit kernel parameters since they're not real files even though they look a lot like them. – David Foerster Feb 07 '16 at 19:12

4 Answers4