Make IP Forwarding permanent?

[theRealBigP]

I setup OpenVPN on my plug a while back, and I forgot that I had enabled IP forwarding on it so that my client machine could see the subnet behind my OpenVPN server. It took me a while to figure out that the reason this no longer worked was because the plug had been rebooted and had therefore reverted back to the original setting of ip_forward=0. Is there some way to make this setting permanent so that it sticks across reboots? Thanks.

[cjm]

See if you have a file called something like /etc/sysctl.conf and add the entry

net.ipv4.ip_forward=1

If the file doesn't exist, locate a startup script (e.g. /etc/rc.local, this depends on your distribution) and add the following line:

echo 1 >/proc/sys/net/ipv4/ip_forward

Thanks,
--Christian

[birdman]

On Ubuntu and Debian you should put a file with the bits you want to add into the /etc/sysctl.d/ directory (see the README file there).  This means you are adding your own file, rather than editing a system one which an OS update may wish to change later.

And you can set forwarding per-interface, rather than globally.  Probably doesn't matter on the Plug, but as a principle it's best to only switch on what you need.

I have an /etc/sysctl.d/60-My-eth-routing.conf file with:

net.ipv4.conf.eth0.forwarding=1
net.ipv4.conf.wlan0.forwarding=1

[theRealBigP]

Thanks guys. I ended up going with birdman's suggestion, as that seemed more 'userland' than cjm's approach. Sure enough, after a reboot I checked the contents of /proc/sys/net/ipv4/ip_forward and it had 1 in there rather than 0, so looks like it's going to stick now.