AIX must terminate all SSH login sessions after 10 minutes of inactivity.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-91447	AIX7-00-003002	SV-101545r1_rule		Medium

Description
Terminating an idle 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 session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at AIX level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean that AIX terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session.

Description

Terminating an idle 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 session will also free up resources committed by the managed network element. Terminating network connections associated with communications sessions includes, for example, de-allocating associated TCP/IP address/port pairs at AIX level, and de-allocating networking assignments at the application level if multiple application sessions are using a single operating system-level network connection. This does not mean that AIX terminates all sessions or network access; it only ends the inactive session and releases the resources associated with that session.

STIG	Date
IBM AIX 7.x Security Technical Implementation Guide	2020-02-24

Details

Check Text ( C-90601r1_chk )
Check the SSH daemon configuration for "ClientAliveInterval" setting with the following command. # grep ClientAliveInterval /etc/ssh/sshd_config ClientAliveInterval 300 If the variable "ClientAliveInterval" is commented out or not set to "300", this is a finding. Check the SSH daemon configuration setting for "ClientAliveCountMax" setting with the following command. # grep ClientAliveCountMax /etc/ssh/sshd_config ClientAliveCountMax 0 If the variable "ClientAliveCountMax" is commented out or not set to "0" this is a finding.

Check Text ( C-90601r1_chk )

Check the SSH daemon configuration for "ClientAliveInterval" setting with the following command.
# grep ClientAliveInterval /etc/ssh/sshd_config
ClientAliveInterval 300

If the variable "ClientAliveInterval" is commented out or not set to "300", this is a finding.

Check the SSH daemon configuration setting for "ClientAliveCountMax" setting with the following command.
# grep ClientAliveCountMax /etc/ssh/sshd_config
ClientAliveCountMax 0

If the variable "ClientAliveCountMax" is commented out or not set to "0" this is a finding.

Fix Text (F-97645r3_fix)
Edit the "/etc/ssh/sshd_config" file and add or update the following lines: ClientAliveInterval 300 ClientAliveCountMax 0 Restart SSH daemon. # stopsrc -s sshd # startsrc -s sshd