The SSH daemon must set a timeout interval on idle sessions.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38608	RHEL-06-000230	SV-50409r1_rule		Low

Description
Causing idle users to be automatically logged out guards against compromises one system leading trivially to compromises on another.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2017-04-28

Details

Check Text ( None )
None

Fix Text (F-43556r1_fix)
SSH allows administrators to set an idle timeout interval. After this interval has passed, the idle user will be automatically logged out. To set an idle timeout interval, edit the following line in "/etc/ssh/sshd_config" as follows: ClientAliveInterval [interval] The timeout [interval] is given in seconds. To have a timeout of 15 minutes, set [interval] to 900. If a shorter timeout has already been set for the login shell, that value will preempt any SSH setting made here. Keep in mind that some processes may stop SSH from correctly detecting that the user is idle.

Fix Text (F-43556r1_fix)

SSH allows administrators to set an idle timeout interval. After this interval has passed, the idle user will be automatically logged out.

To set an idle timeout interval, edit the following line in "/etc/ssh/sshd_config" as follows:

ClientAliveInterval [interval]

The timeout [interval] is given in seconds. To have a timeout of 15 minutes, set [interval] to 900.

If a shorter timeout has already been set for the login shell, that value will preempt any SSH setting made here. Keep in mind that some processes may stop SSH from correctly detecting that the user is idle.