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Sysctl: net.ipv4.ip_forward

This sysctl key defines if a system should allow forwarding of IPv4 network packets. This functionality is required for systems that act as a gateway or router.

IP forwarding is normally not required for most desktops and servers.


0Forwarding of packets is not allowed.
1This system may forward packets to other networks

Most systems have by default net.ipv4.ip_forward set to value 0.

Show current value

The value of the net.ipv4.ip_forward can be retrieved using the sysctl command.

sysctl net.ipv4.ip_forward

or using the proc file system:

sysctl /proc/sys/net/ipv4/ip_forward

Configure new value

To apply a new value, use the option --write, followed by the key and value.

sysctl --write net.ipv4.ip_forward=NEWVALUE

To ensure that these changes are also applied during the next boot, add them to a configuration file, typically something like /etc/sysctl.d/99-custom.conf.


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This article has been written by our Linux security expert Michael Boelen. With focus on creating high-quality articles and relevant examples, he wants to improve the field of Linux security. No more web full of copy-pasted blog posts.

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