I'm trying to discover the nature of this, since it appears to be a relatively new phenomena and I don't know what it could mean (probably nothing good). The sign that I got of it was a long list of notices in my locally-hosted (non-internet enabled) Apache server's error log with messages like these (with increasing port numbers):
[Tue Dec 18 22:10:19.714000 2012] [access_compat:error] [pid 7076:tid 1592] [client 192.168.0.196:59424] AH01797: client denied by server configuration [Tue Dec 18 22:11:41.922000 2012] [access_compat:error] [pid 7076:tid 1592] [client 192.168.0.196:59441] AH01797: client denied by server configuration etc.
Where should I begin looking to figure out the nature of this?
Edit: I know the machine it's coming from, and I do have access to it if need be.