Virtual Private Networks VPNs are an important technology that turns the Internet into a significant business, VPNs set up a secure connections between remote user and other networks by encrypting the packets sent through the Internet. VPNs based on IPsec (Internet Protocol Security). Early VPNs use the multi protocol label switching MPLS VPNs but do not encrypt data, however it adds labels to packets to assign their network path. but later VPNs became secured by using an encrypted packets with cryptographic keys that is exchanged between the sender and the receiver over the Internet. The VPN can be created using the IPsec either with the transport mode (end to end) or with the tunnel mode (portal to portal), the security implication is quite different between these modes. while using the transport mode the payload (the data that transferred) in the IP packet is only encrypted, but the IP header in the transport mode is not encrypted. in the tunnel mode the entire IP packet wich include the payload (data) and the message headers is encrypted. IP sec operate on the network layer 3 on the OSI model, it is implemented a set of cryptographic protocols. Later on the SSL (secure sockets layer) VPNs introduced on 2003 by Netscreen, the technology that offers the same encryption strengths as IPsec except that in SSL VPNs the users log in to dedicated web site that checks for the user and passwords, and use network optimization & data compression to improve performance.