1.99 UBTU-24-600000

Information

The operating system must immediately terminate all network connections associated with SSH traffic after a period of inactivity.

GROUP ID: V-270742
RULE ID: SV-270742r1066715

Automatic session termination addresses the termination of user-initiated logical sessions in contrast to the termination of network connections that are associated with communications sessions (i.e., network disconnect). A logical session (for local, network, and remote access) is initiated whenever a user (or process acting on behalf of a user) accesses an organizational information system. Such user sessions can be terminated (and thus terminate user access) without terminating network sessions.

Session termination terminates all processes associated with a user's logical session except those processes that are specifically created by the user (i.e., session owner) to continue after the session is terminated.

Conditions or trigger events requiring automatic session termination can include, for example, organization-defined periods of user inactivity, targeted responses to certain types of incidents, and time-of-day restrictions on information system use.

This capability is typically reserved for specific Ubuntu 24.04 LTS functionality where the system owner, data owner, or organization requires additional assurance.

Solution

Configure the SSH server to terminate a user session automatically after the SSH client has become unresponsive.

Note: This setting must be applied in conjunction with UBTU-22-255040 to function correctly.

Add or modify the following line in the "/etc/ssh/sshd_config" file:

ClientAliveCountMax 1

Restart the SSH daemon for the changes to take effect:

$ sudo systemctl restart sshd.service

See Also

https://workbench.cisecurity.org/benchmarks/22775

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-10, CAT|II, CCI|CCI-001133, Rule-ID|SV-270742r1066715_rule, STIG-ID|UBTU-24-600000, Vuln-ID|V-270742

Plugin: Unix

Control ID: 777045cc9a24a49e26e29a5eb1cf2923be889df3b2410ed12e2155800ea32752