Offering... RC script for user-level two factor auth about duo_unix HOT 5 CLOSED

Thank you for this observation! We will try to add it to our duo_unix documentation page in the future.

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Great script! Definitely should be in the docs.

This script also runs when scp connects, however during scp there is no tty available and pkill throws an error. Best to add a check to prevent the error. Here is an example of a SmartOS version:

TTY=${SSH_TTY:4}
/opt/local/sbin/login_duo
if [ $? -ne 0 ] ; then echo "You are not authorized! Bye Bye!";
  if [[ $TTY != "" ]]; then pkill -HUP -t $TTY; fi
fi

from duo_unix.

Interesting observation however given that it also means that it won't kill the session for scp at all. We would need to identify a different way to cut off the session in the event it is denied by login_duo otherwise it will connect regardless of if it is approved or denied.

Just for the heck of it I checked sftp and it has a TTY generated but when I checked scp it didn't so that is weird or maybe that is expected behavior. Either way I don't think there is an effective way to terminate the session at this point which makes duo quite ineffective for scp transfers.

if [ ! -z $SSH_TTY ] ; then $HOME/sbin/login_duo -c $HOME/etc/duo/login_duo.conf; if [ $? -ne 0 ] ; then echo "You are not authorized! Bye Bye!"; pkill -SIGHUP -t $SSH_TTY; fi; fi

The above is a one liner now... It is wrapped in a if statement to check for a non-zero SSH_TTY variable before executing so it will skip it on any session that has no tty allocated and silence the error. If someone can figure out how to kill the session when a tty is not allocated then feel free to provide input on that front as I'd be interested as well.

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@shinji257 On SmartOS (Joyent), my updated script does terminate the scp session if I deny the request through Duo. What platform/OS are you testing with?

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@doublerebel Well it would of been NetBSD but I have not had it setup on that server for a long time. From what I remembered login_duo just exited with a return value to be checked. Maybe scp is handling this directly and closing the session?

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