To be completely honest, I do not know if you are telling the truth or not, since the subject line of your thread says "wireless network monitoring." LQ Rule #13 states:
Posts containing information about cracking, piracy, warez, fraud or any topic that could be damaging to either LinuxQuestions.org or any third party will be immediately removed.
Note that even though your post does not contain information about cracking by itself, using these forums to gain information on how to obtain information illegally is against the rules.
That being said, if you really work for a "wireless internet service provider," they would most likely already have a server setup dedicated to protect the internal network.
Now as far as actual tools to use though, you have many different options. Nagios is one of them, along with snort, and many others.
That is just a start. Use google to search around more, as I can not really access sites like those for you.
Good luck and cheers,