Is forbidding concurrent ssh sessions a good idea?

[Elazar Leibovich]

I'm considering to disallow concurrent ssh sessions on a single-purpose
production machine (say, DB server).

I thought of replacing the default shell with a shell that keeps its pid
file in a central place. If such a file already exist, it'll kill the other
running shell before logging in.

Something like

    export LOCKFILE=/tmp/singleshell.pid
    while [ "$(cat $LOCKFILE)" -eq "$LOCKFILE" ]; do
        kill $(cat "$LOCKFILE")
        sleep 1
        kill -9 $(cat "$LOCKFILE")
        echo $PID >$LOCKFILE
    done

    exec /bin/sh

The benefits of that are, making sure it is always one man fixing the
server (what can happen is two people get a call "help, server is not
working", and forgetting to check who else is logged in in the rush). And,
the option of streamline logging. I'll use sudosh2 or some similar
recording shell/recording terminal, and I'll have the exact log of what
happened, no need to correlate events in two shells.

I'd like to hear your opinion and/or experience with such a scheme.

Thanks
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