DISA STIGS Viewer

Finding ID	Version	Rule ID	IA Controls	Severity
V-258829	PHTN-40-000068	SV-258829r958528_rule		Medium

Description

A TCP SYN flood attack can cause a Denial of Service (DOS) by filling a system's TCP connection table with connections in the SYN_RCVD state. Syncookies can be used to track a connection when a subsequent ACK is received, verifying the initiator is attempting a valid connection and is not a flood source. This feature is activated when a flood condition is detected and enables the system to continue servicing valid connection requests. Satisfies: SRG-OS-000142-GPOS-00071, SRG-OS-000420-GPOS-00186

STIG	Date
VMware vSphere 8.0 vCenter Appliance Photon OS 4.0 Security Technical Implementation Guide	2024-07-11

Check Text (C-62569r933546_chk)

At the command line, run the following command to verify TCP syncookies are enabled: # /sbin/sysctl net.ipv4.tcp_syncookies Example result: net.ipv4.tcp_syncookies = 1 If "net.ipv4.tcp_syncookies" is not set to "1", this is a finding.

Fix Text (F-62478r933547_fix)

Navigate to and open: /etc/sysctl.d/zz-stig-hardening.conf Add or update the following line: net.ipv4.tcp_syncookies = 1 At the command line, run the following command to load the new configuration: # /sbin/sysctl --load /etc/sysctl.d/zz-stig-hardening.conf Note: If the file zz-stig-hardening.conf does not exist, it must be created.