I'm running a small script when a user accesses my Linux host via SSH. This script should verify and/or set up Google Authenticator MFA access for the user.

Right now it works as intended with one caveat - at any moment during the MFA configuration process, if the user (ie) CTRL+C's, the setup wizard is interrupted, but the SSH session continues. I need it to log out the user trying to access.

How can I achieve this?

This is what I have added at the bottom of my .bashrc file (please note that this is very new to me and that I'm open to criticism/improvements on my current attempt).

# MFA validation/configuration

if [[ -n $SSH_CONNECTION ]] ; then
        echo "SSH connection to remote host successful."
        echo "testing if MFA is configured..."

        # is this test enough?

        if [ -f "$file" ] ; then
                printf "MFA configured, you may proceed.\n"
                printf "MFA not configured; running setup wizard.\n"

                # the command runs, but the else bit is never reached
                if google-authenticator ; then
                        # I reach this point if I go to the end of the wizard
                        echo "MFA setup successful"
                        # this point is never reached
                        echo "MFA setup failed - logging you out"

You can add line

trap '' 2

at start of you script to disable CTRL+C and

trap 2

in end to enable CTRL+C functional.

This will prevent user from brake you script execution.

Note that this should be added to /etc/bashrc, making it system wide and not user-modifiable


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