"The Linux Gazette...making Linux just a little more fun!"

IP forwarding and Linux

From Hal Pomeranz on Mon, 26 Jul 1999

Jim--

I admit that I'm being lazy and not searching for the answer in a FAQ, but could you tell me the right incantation under Linux to disable IP forwarding on multi-homed machines. Thanks muchly in advance!

--Hal

It's already the default setting for most Linux kernels. However, you can force it with:

echo 0 > /proc/sys/net/ipv4/ip_forward

(you can 'cat' the contents of that node to view the current setting). It's more commonly necessary to use:

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

... to ENABLE the forwarding.

Of course this assumes that you have /proc enabled in your Linux kernel (also the default and STRONGLY recommended). I believe there's also a sysctl() interface to this, in case you've stubbornly built your system without /proc support (and replaced the entire procps suite of utilities including your 'ps' command).

Copyright © 1999, James T. Dennis
Published in The Linux Gazette Issue 44 August 1999

HTML transformation by Heather Stern of Starshine Techinical Services, http://www.starshine.org/

			1	4	7	9
			11	12	14	17
18	19	20	21	24	25	26
28	29	30	31	32	33	34
35	36	37	38	39	40	41
42	43	44	45	46	47	48