modify kernel parameters in linux without using sysctl

Question

I have an embedded system. An old linux OS runs on it. When i enter "uname -r" command i get the version information as "3.3.8-3.4".

I want to modify some of network kernel parameters (increase tcp receive buffer size etc.) in /proc/sys. But sysctl command does not exist in this old linux kernel version. Also sysctl.conf does not exist under /etc directory

I tried changing kernel parameter files manually but system does not allow this operation even for super user.

How can i modify kernel parameters in this linux version?

Answer 1

You can use /proc/sys . For example the following command:

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

... is basically the same as

sysctl -w net.ipv4.ip_forward=1

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However, you'll need to make sure on your own that parameters will be set on boot.