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AlmaLinux OS 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-269419ALMA-09-040170SV-269419r1050302_ruleCCI-002891medium
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. Satisfies: SRG-OS-000395-GPOS-00175, SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109
STIGDate
Cloud Linux AlmaLinux OS 9 Security Technical Implementation Guide2026-02-27

Related Frameworks

1 mapping across 3 frameworks
SCF0 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.

MNT-05.4Remote Maintenance Disconnect Verification
1.00
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (11) 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-11Device Lock
1.00
AC-12Session Termination
1.00
IA-2(8)Access to Accounts — Replay Resistant
1.00
IA-2(9)Network Access to Non-privileged Accounts — Replay Resistant
1.00
IA-5(1)Password-based Authentication
1.00
IA-7Cryptographic Module Authentication
1.00
MA-4Nonlocal Maintenance
1.00
MA-4(7)Disconnect Verification
1.00
SC-10Network Disconnect
1.00
SC-23(1)Invalidate Session Identifiers at Logout
1.00

+1 more (top 10 by confidence shown)

CCI1 mapping
CCI-002891
1.00

Details

Check Text (C-269419r1050302_chk)

Verify that the "ClientAliveInterval" variable is set to a value of "600" or less and "ClientAliveCountMax" is set to "1" by performing the following command: $ sshd -T | grep clientalive clientaliveinterval 600 clientalivecountmax 1 If "ClientAliveInterval" does not have a value of "600" or less, or "ClientAliveCountMax" is not set to "1", this is a finding.

Fix Text (F-73351r1048634_fix)

To configure the SSH server to terminate a user session automatically after the SSH client has become unresponsive, add or modify the following lines in "/etc/ssh/sshd_config": ClientAliveInterval 600 ClientAliveCountMax 1 Alternatively, add the settings to an include file if the line "Include /etc/ssh/sshd_config.d/*.conf" is found at the top of the "/etc/ssh/sshd_config" file: $ cat << EOF | tee /etc/ssh/sshd_config.d/clientalive.conf ClientAliveInterval 600 ClientAliveCountMax 1 EOF Restart the SSH daemon for the settings to take effect: $ systemctl restart sshd.service