When you want to test something with apache2, it's useful to serve it only on localhost to see what happens and make sure everything goes well. So, you just have to edit your /etc/apache2/ports.conf and set the Listen directive ...
"Splunk Enterprise is a fully featured, powerful platform for collecting, searching, monitoring and analyzing machine data". There is a free version of Splunk with some limitations (read here), but it's sufficent to analyze fews hosts logs (< 20). The major disadvatage of this edition is ...
If you're working in large network environment and you have some ip conflicts, you can use arping command under Linux. This command sends arp requests on the Ethernet layer and is a part of iputils package (so arping is available on ...