The NAT technology enables connection from local networks to the Internet using a single IP address. All hosts within the local network can access the Internet di- rectly as if they were on a public network (certain limitations are applied). Services running on local hosts can be mapped to the public IP address.
Network adapter
The equipment that connects hosts to a traffic medium. It can be represented by an Ethernet adapter, TokenRing adapter, by a modem, etc. Network adapters are used by hosts to send and receive packets. They are also referred to throughout this document as a network interface.
P2P network
Packet
Basic data unit transmitted via computer networks. Packets consist of a header which include essential data (i.e. source and destination IP address, protocol type, etc.) and of the data body,. Data transmitted via networks is divided into small segments, or packets. If an error is detected in any packet or a packet is lost, it is not necessary to repeat the entire transmission process, only the particular packet will be
POP3
Post Office Protocol is a protocol that enables users to download messages from a server to their local computer. It is suitable for clients who don’t have a perma- nent connection to the Internet.
Port
PPTP
Microsoft’s proprietary protocol used for design of virtual private networks (see chapters concerning VPN ).
Private IP addresses
Local networks which do not belong to the Internet (private networks) use reserved ranges of IP addresses (private addresses). These addresses cannot be used in
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