I looked at system.log in the system profiler today and see lots of activity at 2 a.m. when I was fast asleep, should I worry? It seems to reset hostname and mentions frequent transitions for interface, looks weird to me (I'm not a teckie!)

Question

I looked at system.log in the system profiler today and see lots of activity at 2 a.m. when I was fast asleep, should I worry? It seems to reset hostname and mentions frequent transitions for interface, looks weird to me (I'm not a teckie!)
This is a section:
May 12 02:05:10 wendy-drapers-macbook configd[14]: setting hostname to "wendy-drapers-macbook.local"
May 12 02:05:29 wendy-drapers-macbook kernel[0]: Auth result for: 00:26:44:14:17:a3 MAC AUTH succeeded
May 12 02:05:29 wendy-drapers-macbook kernel[0]: AirPort: Link Up on en1
May 12 02:05:29 wendy-drapers-macbook mDNSResponder[16]: Note: Frequent transitions for interface en1 (192.168.1.92); network traffic reduction measures in effect
May 12 02:05:29 macbook configd[14]: setting hostname to "macbook.lan"
May 12 02:05:31 macbook mDNSResponder[16]: Note: Frequent transitions for interface en1 (FE80:0000:0000:0000:021E:C2FF:FEB3:1A3E); network traffic reduction measures in effect
May 12 02:05:34 macbook com.apple.launchd[1] (org.samba.nmbd): Throttling respawn: Will start in 5 seconds

Answer 1

I've been seeing messages exactly like that (and many, many other kinds) in the Console since the first version of OS X.  They look menacing but are harmless.
You don't need any kind of security software.
Just surf the web carefully, pay attention to where you're going and don't install anything that you don't recognize.  If you are asked to enter an admin user name and password, DON'T.  Unless you know for sure that you initiated the installation from a known and reliable source (like Apple).
Mac malware relies on social engineering.  No amount of security/anti-virus, blah, blah, blah software is going to help.