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RHEL 9 must be configured so that all network connections associated with SSH traffic are terminated after 10 minutes of becoming unresponsive.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-257996RHEL-09-255100SV-257996r1045055_ruleCCI-001133medium
Description
Terminating an unresponsive SSH session within a short time period reduces the window of opportunity for unauthorized personnel to take control of a management session enabled on the console or console port that has been left unattended. In addition, quickly terminating an idle SSH session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, deallocating associated TCP/IP address/port pairs at the operating system level and deallocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean the operating system terminates all sessions or network access; it only ends the unresponsive session and releases the resources associated with that session. RHEL 9 utilizes /etc/ssh/sshd_config for configurations of OpenSSH. Within the sshd_config, the product of the values of "ClientAliveInterval" and "ClientAliveCountMax" are used to establish the inactivity threshold. The "ClientAliveInterval" is a timeout interval in seconds, after which if no data has been received from the client, sshd will send a message through the encrypted channel to request a response from the client. The "ClientAliveCountMax" is the number of client alive messages that may be sent without sshd receiving any messages back from the client. If this threshold is met, sshd will disconnect the client. For more information on these settings and others, refer to the sshd_config man pages. Satisfies: SRG-OS-000126-GPOS-00066, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109, SRG-OS-000395-GPOS-00175
STIGDate
Red Hat Enterprise Linux 9 Security Technical Implementation Guide2025-05-14

Related Frameworks

3 mappings across 5 frameworks
SCF0 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (8) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

IAC-01.2Authenticate, Authorize and Audit (AAA)
1.00
IAC-02Identification & Authentication for Organizational Users
1.00
IAC-03Identification & Authentication for Non-Organizational Users
1.00
IAC-04Identification & Authentication for Devices
1.00
IAC-05Identification & Authentication for Third-Party Technology Assets, Applications and/or Services (TAAS)
1.00
IAC-25Session Termination
1.00
MNT-05.4Remote Maintenance Disconnect Verification
1.00
NET-07Network Connection Termination
1.00
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (39) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

AC-10Concurrent Session Control
1.00
AC-11Device Lock
1.00
AC-11(1)Pattern-hiding Displays
1.00
AC-12Session Termination
1.00
AC-12(1)User-initiated Logouts
1.00
AC-12(2)Termination Message
1.00
AC-2(1)Automated System Account Management
1.00
AC-2(11)Usage Conditions
1.00
AC-2(2)Automated Temporary and Emergency Account Management
1.00
AC-2(3)Disable Accounts
1.00

+29 more (top 10 by confidence shown)

NIST 800-1710 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (2) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

3.1.11
1.00
3.13.9
1.00
CCI3 mappings
CCI-001133
1.00
CCI-002361
1.00
CCI-002891
1.00
NIST CSF 2.00 mappings

No source states a mapping between these directly.

Also reachable in 3 hops (1) derived by us, not asserted by any source

Each of these is a route we composed by chaining published mappings. No publisher states a relationship between the two endpoints.

PR.AA-03
1.00

Who does this work

7 NICE work roles and 5 EC-Council certifications.

This is an inference across published mappings, not a single claim by anyone. This check maps to a control, which maps to a Cybersecurity Framework outcome, which NIST assigns to the work roles below. EC-Council separately maps its certifications to those same roles.

A certification prepares someone for a role. It is not evidence that a holder is qualified, and neither NIST nor EC-Council has stated that any certification here addresses this check.

Work-role assignments published by NIST (NICE Framework Components 2.2.0 and the CSF 2.0 OLIR crosswalk). Certification mappings published by EC-Council.

Details

Check Text (C-257996r1045055_chk)

Verify the "ClientAliveInterval" variable is set to a value of "600" or less by performing the following command: $ sudo /usr/sbin/sshd -dd 2>&1 | awk '/filename/ {print $4}' | tr -d '\r' | tr '\n' ' ' | xargs sudo grep -iH '^\s*clientaliveinterval' ClientAliveInterval 600 If "ClientAliveInterval" does not exist, does not have a value of "600" or less in "/etc/ssh/sshd_config", or is commented out, this is a finding.

Fix Text (F-61661r1045054_fix)

Note: This setting must be applied in conjunction with RHEL-09-255095 to function correctly. Configure the SSH server to terminate a user session automatically after the SSH client has been unresponsive for 10 minutes. Modify or append the following lines in the "/etc/ssh/sshd_config" or in a file in "/etc/ssh/sshd_config.d": ClientAliveInterval 600 For the changes to take effect, the SSH daemon must be restarted. $ sudo systemctl restart sshd.service