Information
TMOUT is an environmental setting that determines the timeout of a shell in seconds.
- TMOUT=
n
- Sets the shell timeout to
n
seconds. A setting of TMOUT=0 disables timeout.
- readonly TMOUT- Sets the TMOUT environmental variable as readonly, preventing unwanted modification during run-time.
- export TMOUT - exports the TMOUT variable
System Wide Shell Configuration Files:
- /etc/profile - used to set system wide environmental variables on users shells. The variables are sometimes the same ones that are in thebash_profile however this file is used to set an initial PATH or PS1 for all shell users of the system. Is only executed for interactive
login
shells, or shells executed with the --login parameter.
- /etc/profile.d - /etc/profile will execute the scripts within /etc/profile.d/*.sh It is recommended to place your configuration in a shell script within /etc/profile.d to set your own system wide environmental variables.
- /etc/bash.bashrc - System wide version of bash.bashrc etc/bash.bashrc also invokes /etc/profile.d/*.sh if
non-login
shell, but redirects output to /dev/null if
non-interactive.
Is only executed for
interactive
shells or if BASH_ENV is set to /etc/bash.bashrc
Setting a timeout value reduces the window of opportunity for unauthorized user access to another user's shell session that has been left unattended. It also ends the inactive session and releases the resources associated with that session.
Solution
Review /etc/bash.bashrc /etc/profile and all files ending in *.sh in the /etc/profile.d/ directory and remove or edit all TMOUT=_n_ entries to follow local site policy.
TMOUT should:
- Be configured once, as multiple lines, or a single line, in one and only one of the following locations:
- A file in the /etc/profile.d/ directory ending insh
- /etc/profile
- /etc/bash.bashrc
- Not exceed 900
- Not be equal to 0
Multiple line example:
TMOUT=900
readonly TMOUT
export TMOUT
Single line example:
readonly TMOUT=900 ; export TMOUT