App-level Tunneling between Tunneling, Encapsulation, and clients and servers Dialup Phe one Lines communicate across a non-IP network. There need a socket simulation library. 且→ts L UDP dient apg SLIP and PPP have bees designed to send IP with support for network system network hould ip transmission across a d be viewed as a form of tunneling or ei Two opinions Clients and servers in Chapter 5: Tunneling and Application Gateway constrained environments Chapter goa: The reality of multiple technologies Multiprotocol environment Not all computers have direct access to the Internet Mixing network technologies Access limitations can complicate client and servers Encapsulation and tunneling Economic, political and technical reasons Result in incompatible systems without s Clients and servers in constrained interoperability environments Computers with limited functionality Connectivity constrains that arise from security Application gateway examples Partition computers into secure and unsecure subsets Computers in one partition cannot dire Chapter 5: Tunneling and Application Gateway Using application gateways Chapter goal: A single, powerful technique to overcome a Multiprotocol environment connectivity constraints-application gateway Mixing network technologies Adding application programs that run on Encapsulation and tunneling s Clients and servers in constrained Intermediate machine is called gateway machine. environments For example, mail gateway Application gateways3 哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 13 App-level Tunneling between clients and servers „ Application-level tunneling „ App-level tunneling makes it possible for clients and servers to use IP protocols to communicate across a non-IP network. „ There need a socket simulation library. UDP client app. Socket simulation library UDP client app. Socket simulation library Operating system with support for network system Operating system with support for network system Network system 哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 14 Tunneling, Encapsulation, and Dialup Phone Lines „ SLIP and PPP have bees designed to send IP across a dialup channel. „ Should IP transmission across a dialup connection be viewed as a form of tunneling or encapsulation? „ Two opinions 哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 15 Chapter 5: Tunneling and Application Gateway Chapter goal: „ Multiprotocol environment „ Mixing network technologies „ Encapsulation and tunneling „ Clients and servers in constrained environments „ Application gateways „ Application gateway examples 哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 16 Clients and servers in constrained environments „ The reality of multiple technologies „ Not all computers have direct access to the Internet „ Access limitations can complicate client and servers „ Economic, political and technical reasons „ Result in incompatible systems without interoperability „ Computers with limited functionality „ Connectivity constrains that arise from security „ Partition computers into secure and unsecure subsets. „ Computers in one partition cannot directly access services available on computers in the other partition. 哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 17 Chapter 5: Tunneling and Application Gateway Chapter goal: „ Multiprotocol environment „ Mixing network technologies „ Encapsulation and tunneling „ Clients and servers in constrained environments „ Application gateways „ Application gateway examples 哈工大计算机学院 李全龙 Network Application Development Tunneling and Application Gateway 18 Using application gateways „ A single, powerful technique to overcome connectivity constraints-application gateway. „ Adding application programs that run on intermediate machines „ Relay information „ Intermediate machine is called gateway machine. „ For example, mail gateway