Set SSH Client Alive Count Max to zero

An XCCDF Rule

Description

The SSH server sends at most ClientAliveCountMax messages during a SSH session and waits for a response from the SSH client. The option ClientAliveInterval configures timeout after each ClientAliveCountMax message. If the SSH server does not receive a response from the client, then the connection is considered unresponsive and terminated. To ensure the SSH timeout occurs precisely when the ClientAliveInterval is set, set the ClientAliveCountMax to value of 0 in /etc/ssh/sshd_config:

Rationale

This ensures a user login will be terminated as soon as the ClientAliveInterval is reached.

ID: xccdf_org.ssgproject.content_rule_sshd_set_keepalive_0
Severity: Medium
References: 1 12 13 14 15 16 18 3 5 7 8

5.5.6

APO13.01 BAI03.01 BAI03.02 BAI03.03 DSS01.03 DSS03.05 DSS05.04 DSS05.05 DSS05.07 DSS05.10 DSS06.03 DSS06.10

3.1.11

CCI-000879 CCI-001133 CCI-002361

164.308(a)(4)(i) 164.308(b)(1) 164.308(b)(3) 164.310(b) 164.312(e)(1) 164.312(e)(2)(ii)

4.3.3.2.2 4.3.3.5.1 4.3.3.5.2 4.3.3.6.1 4.3.3.6.2 4.3.3.6.3 4.3.3.6.4 4.3.3.6.5 4.3.3.6.6 4.3.3.6.7 4.3.3.6.8 4.3.3.6.9 4.3.3.7.2 4.3.3.7.3 4.3.3.7.4 4.3.4.3.3

SR 1.1 SR 1.10 SR 1.2 SR 1.3 SR 1.4 SR 1.5 SR 1.7 SR 1.8 SR 1.9 SR 2.1 SR 6.2

A.12.4.1 A.12.4.3 A.14.1.1 A.14.2.1 A.14.2.5 A.18.1.4 A.6.1.2 A.6.1.5 A.7.1.1 A.9.1.2 A.9.2.1 A.9.2.2 A.9.2.3 A.9.2.4 A.9.2.6 A.9.3.1 A.9.4.1 A.9.4.2 A.9.4.3 A.9.4.4 A.9.4.5

CIP-004-6 R2.2.3 CIP-007-3 R5.1 CIP-007-3 R5.2 CIP-007-3 R5.3.1 CIP-007-3 R5.3.2 CIP-007-3 R5.3.3

AC-12 AC-17(a) AC-2(5) CM-6(a) SC-10

DE.CM-1 DE.CM-3 PR.AC-1 PR.AC-4 PR.AC-6 PR.AC-7 PR.IP-2

Req-8.1.8

SRG-OS-000126-GPOS-00066 SRG-OS-000163-GPOS-00072 SRG-OS-000279-GPOS-00109

CCE-83406-9
Updated: about 1 year ago

---
apiVersion: machineconfiguration.openshift.io/v1
kind: MachineConfig
spec:
  config:
    ignition:      version: 3.1.0
    storage:
      files:
      - contents:
          source: data:,{{ 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}}
        mode: 0600
        path: /etc/ssh/sshd_config
        overwrite: true

Set SSH Client Alive Count Max to zero

Description

Rationale

Remediation - Kubernetes Patch