During the workshop we would like to give an overall theoretical picture of the operation of RFID (Radio Frequency Identification) technology, then we will present its weaknesses and vulnerabilities in detail. We will demonstrate in practice how the various RFID based access control systems can be evaded, no matter if they are LF (Low Frequency) or HF (High Frequency) solutions. The most important thing is that at the end of the workshop neither of the doors remains dry...that is closed. Throughout the demonstration we will use the Proxmark3 developing device to make emulations and clones. It is a board on which the integrated circuits can be freely programmable thus providing developers with high flexibility. For this very reason we wish to demonstrate the versatility of the Proxmark3, which was developed by Jonathan Westhues for the research of RFID systems.