How to Ubuntu Linux Increase TCP buffer size

echo 12582912 /proc/sys/net/core/rmem_default
echo 12582912 /proc/sys/net/core/wmem_default
echo 25165824 > /proc/sys/net/core/rmem_max
echo 25165824 > /proc/sys/net/core/wmem_max
echo '10240 12582912 25165824' > /proc/sys/net/ipv4/tcp_rmem
echo '10240 12582912 25165824' > /proc/sys/net/ipv4/tcp_wmem
echo 1 > /proc/sys/net/ipv4/route/flush