The SUSE operating system must be configured to use TCP syncookies.

From SLES 12 Security Technical Implementation Guide

Associated with: CCI-001095

SV-92181r1_rule The SUSE operating system must be configured to use TCP syncookies.

Vulnerability discussion

Denial of Service (DoS) is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. Managing excess capacity ensures that sufficient capacity is available to counter flooding attacks. Employing increased capacity and service redundancy may reduce the susceptibility to some DoS attacks. Managing excess capacity may include, for example, establishing selected usage priorities, quotas, or partitioning.

Check content

Verify the SUSE operating system is configured to use TCP syncookies. Check to see if syncookies are used with the following command: # sudo sysctl net.ipv4.tcp_syncookies net.ipv4.tcp_syncookies = 1 If the value is not set to "1", this is a finding.

Fix text

Configure the SUSE operating system to use TCP syncookies by running the following command as an administrator: # sudo sysctl -w net.ipv4.tcp_syncookies=1 If "1" is not the system's default value, add or update the following line in "/etc/sysctl.conf": net.ipv4.tcp_syncookies = 1

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