overwriting default $PATH
I am trying to lock down regular users on a Raspbian installation. I'll be using rbash
for that.
I want to edit the PATH file so that only ~/bin
files can be executed.
I've stripped $PATH
from /etc/profile/
:
if [ "`id -u`" -eq 0 ]; then
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
else
PATH=""
fi
export PATH
I've stripped $PATH
from /etc/login.defs
:
# cat /etc/login.defs | grep PATH=
ENV_SUPATH PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
ENV_PATH PATH=""
The /etc/environment
file is empty:
~ # cat /etc/environment
~ #
The local user's .profile
file contains only the following:
$ cat .profile
# if running bash
if [ -n "$BASH_VERSION" ]; then
# include .bashrc if it exists
if [ -f "$HOME/.bashrc" ]; then
. "$HOME/.bashrc"
fi
fi
# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
PATH="$HOME/bin"
fi
That works fine when running ssh user@host
:
$ free
-rbash: free: command not found
$ uname
-rbash: uname: command not found
$ echo $PATH
/home/user/bin
However, when running ssh -t user@host bash --noprofile
.profile
is not executed, and I still get access to a fully working $PATH:
$ echo $PATH
/usr/local/bin:/usr/bin:/bin:/usr/games
$ uname
Linux
What am I missing here? Where else is the $PATH
file defined?
Solution 1:
It's set by sshd itself:
$ strings /usr/sbin/sshd | grep games
/usr/local/bin:/usr/bin:/bin:/usr/games
In man ssh
under ENVIRONMENT
it says:
ssh will normally set the following environment variables:
(...)
PATH Set to the default PATH, as specified when compiling ssh.
To prevent sshd from setting PATH to the default value set
PermitUserEnvironment yes
in /etc/ssh/sshd_config and set a new value of PATH in ~/.ssh/environment, for example
PATH=~/bin
And restart SSH service:
sudo service ssh restart
BTW, you can get all of this information from man sshd_config
.