Configure TCP for faster connections and transfers


On a default Linux Box, the TCP settings may not be optimise for “bigger” available network bandwidth connections and transfer available for 100MB+. Currently, most TCP settings are optimise for 10MB settings. I’m relying on the article from Linux Tweaking from SpeedGuide.net to configure the TCP

The TCP Parameters to be configured are

/proc/sys/net/core/rmem_max – Maximum TCP Receive Window
/proc/sys/net/core/wmem_max – Maximum TCP Send Window
/proc/sys/net/ipv4/tcp_timestamps – timestamps (RFC 1323) add 12 bytes to the TCP header
/proc/sys/net/ipv4/tcp_sack – tcp selective acknowledgements.
/proc/sys/net/ipv4/tcp_window_scaling – support for large TCP Windows (RFC 1323). Needs to be set to 1 if the Max TCP Window is over 65535.

There are 2 methods to apply the changes.

Methods 1: Editing the /proc/sys/net/core/. However, do note that the settings will be lost on reboot.

echo 256960 > /proc/sys/net/core/rmem_default
echo 256960 > /proc/sys/net/core/rmem_max
echo 256960 > /proc/sys/net/core/wmem_default
echo 256960 > /proc/sys/net/core/wmem_max
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
echo 1 > /proc/sys/net/ipv4/tcp_sack
echo 1 > /proc/sys/net/ipv4/tcp_window_scaling

Method 2: For a more permanent settings, you have to configure /etc/sysctl.conf.

net.core.rmem_default = 256960
net.core.rmem_max = 256960
net.core.wmem_default = 256960
net.core.wmem_max = 256960
net.ipv4.tcp_timestamps = 0
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1

Execute sysctl -p to make these new settings take effect.

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