By tunning kernel parameters can improve linux socket io performance.  The settings for sysctl.conf below apply for Fedora, RedHat, Centos OS as well as other Linux flavors. These settings will improve your server network performance and some little protection against ddos attacks as well.

# Kernel sysctl configuration file for Red Hat Linux
#
# For binary values, 0 is disabled, 1 is enabled. See sysctl(8) and
# sysctl.conf(5) for more details.

# Disables packet forwarding
net.ipv4.ip_forward=0

# Disables IP source routing
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.lo.accept_source_route = 0 Read the rest