how to make oneself invisible on a network

[abhishekit]

I think I have seen somewhere on my comp , how to be invisible on a LAN(wireless or wired). I am not able to find it now.
Can anyone please tell me how is it done.
thanks

[SiliconAddict]

Well there is no 100% certain way of cloaking yourself on a network but a good firewall will be able to block many, not all, scanning tools that are out there.

[ratspg]

What kind of software tools on OS X help?

[geerlingguy]

Well...

If you go to System Preferences>Sharing, that's a place to get started in protection. You can disable all unneccessary sharing services, and make sure you're firewall is on with all unneccessary ports blocked. Otherwise you can go to MacUpdate.com's Networking section to find some great security tools. However, I've never in my life had any security breaches on my computer, but I do block almost all my ports and never run any even remotely questionable software.