OpenControls Logo

STIG Viewer

STIGViewer Support

RHEL 10 must be configured so that all network connections associated with Secure Shell (SSH) traffic terminate after becoming unresponsive.

Overview

Finding IDVersionRule IDIA ControlsSeverity
V-281269RHEL-10-700660SV-281269r1184769_ruleCCI-001133medium
Description
Terminating an idle 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. 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 inactive session and releases the resources associated with that session. RHEL 10 uses "/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. OpenSSH uses the first occurrence of a keyword it sees, and drop-in files are read in lexicographical order at the start of the configuration. Red Hat recommends using drop-in files rather than changing base configuration files. Satisfies: SRG-OS-000163-GPOS-00072, SRG-OS-000279-GPOS-00109
STIGDate
Red Hat Enterprise Linux 10 Security Technical Implementation Guide2026-03-11

Related Frameworks

1 mapping across 4 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.

NET-07Network Connection Termination
1.00
NIST 800-530 mappings

No source states a mapping between these directly.

Also reachable in 2 hops (24) 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-11(1)Pattern-hiding Displays
1.00
AC-12Session Termination
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
AC-2(4)Automated Audit Actions
1.00
AC-7Unsuccessful Logon Attempts
1.00

+14 more (top 10 by confidence shown)

NIST 800-1710 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.

3.13.9
1.00
CCI1 mapping
CCI-001133
1.00

Details

Check Text (C-281269r1184769_chk)

Verify RHEL 10 network connections associated with SSH traffic terminate after becoming unresponsive. Set the "ClientAliveCountMax" to "1" 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*clientalivecountmax' /etc/ssh/sshd_config.d/10-stig.conf:ClientAliveCountMax 1 Verify the runtime setting with the following command: $ sudo sshd -T | grep -i clientalivecountmax clientalivecountmax 1 If the "ClientAliveCountMax" keyword is not set to a value of "1" in a drop-in that lexicographically precedes 50-redhat.conf, or if no output is returned, this is a finding.

Fix Text (F-85735r1166758_fix)

Configure RHEL 10 to automatically terminate all network connections associated with SSH traffic at the end of a session or after 10 minutes of inactivity. In "/etc/ssh/sshd_config.d", create a drop file that will lexicographically precede 50-redhat.conf and add the following line: ClientAliveCountMax 1 Restart the SSH daemon with the following command for the changes to take effect: $ sudo systemctl restart sshd.service