How to achieve E-Mail Notification on root login?

Polytropon freebsd at
Tue Feb 12 13:46:24 UTC 2013

On Tue, 12 Feb 2013 13:24:52 +0100, Matthias Petermann wrote:
> Hello,
> given there is a FreeBSD system with users in the wheel group, what is  
> the best practise
> to send out a notification via E-Mail if one of them becomes root via  
> su? In an ideal
> case the E-Mail would contain the user name and the time.
> I thought about using sudo but this is not in the base system which I  
> would prefer.

I'm not sure if there already is a solution (provided in the
base system) that offers this functionality, but the fact of
a user having used "su" to "su root" is logged by the system.
The line is appended to /var/log/messages:

	Feb 12 14:40:57 r56 su: poly to root on /dev/pts/2

The information you want is in there, and you could either use
the whole line, or apply some sed, awk or even perl to form a
message with less information (only date and user).

A scripted solution could monitor /var/log/messages for changes
and use the system's builtin mailer to deliver the message. Tools
like "tail -f", "grep" and "| mail" could be involved. It should
be quite trivial to implement this and add a custom rc.d-style
script (or even few lines in ye olde /etc/rc.local).

Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...

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