NAT translates between local (private) IP addresses and public addresses. This provides a simple method of allowing Internet access and a limited way of allowing access to local resources from the Internet.

Proxy Server acts as a proxy between local computers and the Internet. The proxy’s IP address is the only one exposed to the public network. Proxy Server also provides additional security features, such as customizable filters and user-based security.

A VPN protocol based on the PPP (Point-to-Point Protocol) dial-up protocol. PPTP encapsulates local data within IP packets for transmission via the public network. Windows 2000 encrypts PPTP data using MPPE (Microsoft Point-to-Point Encryption).

An IETF standard for VPN tunneling. L2TP is based on a combination of L2F (Layer 2 Forwarding) and PPTP.

Requires both the SMB client and server to identify themselves, preventing an unauthorized node from intercepting file sharing messages

Adds digital signatures to SMB messages, further preventing the possibility of unauthorized access