"su" command causes log message, what's it mean?

[KenJackson]

Every time I execute the su command (to become root) on my home computer, a message is logged in /var/log/secure. The su command succeeds without any error message to the terminal.

... su: pam_succeed_if: requirement "user ingroup wheel" not met by user "ken"

I suppose I could get rid of this by putting myself in the wheel group, but

• Why do I get the message?
• What's the point of griping if it doesn't prevent access?
• Is there any security implication to joining wheel?
• Can I get rid of the message, other than joining wheel?

[bigtomrodney]

This might sound like a counter-intuitive answer, but if my research is correct the whole idea is to log users who aren't specifically permitted to use 'su'.

So anyone who should be using 'su' regularly should be in the wheel group, and anyone who doesn't have this will be logged. I find this odd because I seem to remember using distributions before (I think Mandrake was one) where you couldn't use su at all unless you were in the wheel group. I guess it's just to seperate people who should use it from people who shouldn't or whose use of it should be monitored. It would make more sense to me to just not allow them.