I HAVE ABOUT 25 USERS IN MY WIRELESS NETWORK AND I HAVE THIS PROBLEM, I HAVE MY ROUTERS DHCP ENABLE, USERS TAKE DYNAMIC IPS FROM MY ROUTER BUT, SOMETIMES THEY EXPERIMENT AND PUT A ROUTER WITH DHCP ANABLE OR PUT STATIC IPS IN THE LAN CARDS AND USE IPS ALL READY USED AND MAKE MY NETWORK CHRASH.
IS THERE ANY THING THAT I CAN DO TO PREVENT THIS?
I AM USING A RB133 FOR MY WIRELESS NETWORK
THANK YOU

yes, there are many of methods how to avoid this. For example:
authehtificate users. You can use Mikrotik hotspot facility for that small network.
You can bond IP address with MAC address so there no bussines when this pair doesnt match...(until your client is as smart as is able to change MAC address)
Interesting parts lying around IP->arp
There are incredible abilities in the RouterOS. But - How your system works depends on you. RouterOS is like LEGO.
You can build anything you can imagine, but you have to study ROS the manual

I would recommend you use hotspot. It works with any clients setup of IPs- all parameters are given upon user name and password, no matter what IP is your "hackig" client trying to set at his side-works on lower level of ISO/OSI model - quickiest solution.

cheers

Patrik

I use PPPoE to avoid this kind of problem for my bad and naughty users.
But to be honest i have tried PPPoE over Wireless and it didnt work.

Once i solved how to make it work on Wireless, then this could be the best solution for this case

T3rm, what exactly was your problem with pppoe over wireless ?