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I've been doing some research into improving performance for OpenVPN and I found out about setting fastforwarding to 1 but when I tried I got the error error: "net.inet.ip.fastforwarding" is an unknown key and tried error: "net.ipv4.ip.fastforwarding" is an unknown keyand wanted to know if I needed to load a module?

This is a CentoOS 6.x 64bit box.

Jason
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2 Answers2

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You can see the list of kernel parameters using the command:

$ sysctl -a

I looked on a CentOS 6.x system along with a Ubuntu 12.04 system and neither had that parameter too. 

$ sysctl -a | grep forwarding

I wonder if it's a BSD only parameter?This forum thread shows it as just being a pfSense & BSD option, net.inet.ip.fastforwarding performance tweak

I haven't found it referenced anywhere except in connection to pfsense. Googling for "net.inet.ip.fastforwarding" only shows BSD related links.

This tutorial, FreeBSD Tuning and Optimization also shows it as just a BSD option.

net.inet.ip

This entire tree doesn't even exist in Linux, it would appear to be BSD only Kernel Parameters. Here's a post that covers the rest of them, titled: FreeBSD net.inet.ip Sysctls Explained. Linux uses net.ipv4.inet.

slm
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The net.inet.ip.fastforwarding is a FreeBSD sysctl option, which will enable an optimization path in the network stack.

It was introduced to the FreeBSD kernel in 2003. The fast forwarding path omits some checks for packets being forwarded to an outgoing interface. Non-unicast packets, packets with IP options or packets destined to local IP addresses fall back to the normal processing path.

Thomas Nyman
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