STIGQter: STIG Summary: Red Hat Enterprise Linux 10 Security Technical Implementation Guide Version: 1 Release: 2 Benchmark Date: 01 Jul 2026:

RHEL 10 must be configured to use Transmission Control Protocol (TCP) syncookies.

DISA Rule

SV-281340r1167170_rule

Vulnerability Number

V-281340

Group Title

SRG-OS-000420-GPOS-00186

Rule Version

RHEL-10-800080

Severity

CAT II

CCI(s)

• CCI-002385 - Protect against or limit the effects of organization-defined types of denial of service events.
• CCI-001095 - Manage capacity, bandwidth, or other redundancy to limit the effects of information flooding types of denial of service attacks.

Weight

10

Fix Recommendation

Configure RHEL 10 to use TCP syncookies.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/99-ipv4_tcp_syncookies.conf

Add the following line to the file:

net.ipv4.tcp_syncookies = 1

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system

Check Contents

Verify RHEL 10 is configured to use Internet Protocol version 4 (IPv4) TCP syncookies.

Check the value of all "net.ipv4.tcp_syncookies" variables with the following command:

$ sudo sysctl net.ipv4.tcp_syncookies
net.ipv4.tcp_syncookies = 1

If the network parameter "ipv4.tcp_syncookies" is not equal to "1", or nothing is returned, this is a finding.

Vulnerability Number

V-281340

Documentable

False

Rule Version

RHEL-10-800080

Severity Override Guidance

Verify RHEL 10 is configured to use Internet Protocol version 4 (IPv4) TCP syncookies.

Check the value of all "net.ipv4.tcp_syncookies" variables with the following command:

$ sudo sysctl net.ipv4.tcp_syncookies
net.ipv4.tcp_syncookies = 1

If the network parameter "ipv4.tcp_syncookies" is not equal to "1", or nothing is returned, this is a finding.

Check Content Reference

M

Target Key

5733