STIGQter: STIG Summary: Canonical Ubuntu 22.04 LTS Security Technical Implementation Guide Version: 2 Release: 9 Benchmark Date: 01 Jul 2026:

Ubuntu 22.04 LTS must be configured to use TCP syncookies.

DISA Rule

SV-260522r1069097_rule

Vulnerability Number

V-260522

Group Title

SRG-OS-000142-GPOS-00071

Rule Version

UBTU-22-253010

Severity

CAT II

CCI(s)

CCI-001095 - Manage capacity, bandwidth, or other redundancy to limit the effects of information flooding types of denial of service attacks.

Weight

Fix Recommendation

Configure Ubuntu 22.04 LTS to use TCP syncookies by using the following command:

$ 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

Check Contents

Verify Ubuntu 22.04 LTS is configured to use TCP syncookies by using the following command:

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

If the value is not "1", this is a finding.

Check the saved value of TCP syncookies by using the following command:

$ sudo grep -ir net.ipv4.tcp_syncookies /etc/sysctl.d/*.conf /run/sysctl.d/*.conf /usr/local/lib/sysctl.d/*.conf /usr/lib/sysctl.d/*.conf /lib/sysctl.d/*.conf /etc/sysctl.conf 2> /dev/null

If the "net.ipv4.tcp_syncookies" option is not set to "1", is commented out, or is missing, this is a finding.

If conflicting results are returned, this is a finding.

Vulnerability Number

V-260522

Documentable

False

Rule Version

UBTU-22-253010

Severity Override Guidance

Check Content Reference

Target Key

5594