TCP backlog queue sizes must be set appropriately.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-23741	GEN003601	SV-45720r1_rule		Medium

Description
To provide some mitigation to TCP Denial of Service attacks, the TCP backlog queue sizes must be set to at least 1280 or in accordance with product-specific guidelines.

STIG	Date
SUSE Linux Enterprise Server v11 for System z Security Technical Implementation Guide	2018-09-19

Details

Check Text ( C-43087r1_chk )
# cat /proc/sys/net/ipv4/tcp_max_syn_backlog If the result is not 1280 or greater, this is a finding.

Fix Text (F-39118r1_fix)
Edit /etc/sysctl.conf and add a setting for "net.ipv4.tcp_max_syn_backlog=1280". Procedure: # echo "net.ipv4.tcp_max_syn_backlog=1280" >> /etc/sysctl.conf # sysctl -p