OSI-model. Mogelijke toepassingen van netwerken. Protocollen. Eenvoudig MS-DOS netwerk (LAN) Novell, IPX / SPX. Applicatie laag.

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1 OSI-model Applicatie laag Presentatie laag Sessie laag Transport laag Netwerk afhankelijk Netwerk laag Datalink laag Fysieke laag Mogelijke toepassingen van netwerken Protocollen Fileserver-systems Remote execution / log-on Distributed systems Resource sharing (printer, scanner) Document sharing (www) Mail Voice (radio, telefonie) Video... An agreed-upon format for transmitting data between two devices. The Point-to-Point Protocol (PPP) Telnet IPX/SPX - Novell NFS RPC X-window Apple talk Netbeui Novell, IPX / SPX Eenvoudig MS-DOS netwerk (LAN) IPX : Internetworking Packet Exchange SPX : Sequence Packet Exchange SPX ligt bovenop IPX en wordt dus ingekapseld in IPX! 1

2 TCP / IP Layers in the TCP/IP stack IP : Internet Protocol. IP specifies the format of packets, also called datagrams (soort brievenpost), and the addressing scheme. (de ip-laag verzorgt de routering) TCP : Transmission Control Protocol Whereas the IP protocol deals only with packets, TCP enables two hosts to establish a connection and exchange streams of data. TCP guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent. 4 Application e.g. HTTP, FTP, DNS (OSI layers 5 through 7) 3 Transport (OSI layers 4 and 5) e.g. TCP, UDP, RTP, SCTP 2 Internetwork (OSI layer 3) For TCP/IP this is the Internet Protocol (IP) 1 Link (OSI layers 1 and 2) e.g. Ethernet, Wi-Fi, MPLS, etc IP-header IP-adres waarden per octet liggen tussen 0 en IP-adres op het internet An IP address consists of two parts, one identifying the network and one identifying the node, or host. The Class of the address determines which part belongs to the network address and which part belongs to the node address Class A - supports 16 million hosts on each of 126 networks Class B - supports 65,000 hosts on each of 16,000 networks Class C - supports 254 hosts on each of 2 million networks 2

3 Niet routeerbare adressen TCP-header Beginadres Eindadres loopback Het poortnummer is gekoppeld aan een bepaalde applicatie. Poort 80 wordt bijv. gebruikt voor http verkeer UDP (Universal Datagram Protocol) Protocol stack voor TCP/IP FTP via poort 21, HTTP via 80, telnet via 23, NNTP via 119, SMTP via 25 (zie /etc/services op een linuxmachine voor een lijst met standaard poortnummers) Eenvoudig netwerk met router Pauze 10 minuten ethernet, MAC address ARP : Address Resolution Protocol, a network layer protocol used to convert an IP address into a physical address (Data Link Control address or MAC address). DHCP : Dynamic Host Configuration Protocol, a protocol for assigning dynamic IP addresses to devices on a network. 3

4 IP versie 6 Internet Protocol next generation V: 4-bit Internet Protocol version number = 6. Prio: 4-bit Priority value. Flow Label: 24-bit field, Quality of Service. Payload Length: 16-bit unsigned integer. Length of payload, i.e., the rest of the packet following the IPng header, in octets. Next Hdr: 8-bit selector. Identifies the type of header immediately following the IPng header. Hop Limit: 8-bit unsigned integer. Decremented by 1 by each node that forwards the packet. The packet is discarded if Hop Limit is decremented to zero. Source Address: 128 bits. Destination Address: 128 bits. RPC : Remote Procedure Call DCE : Distributed Computing Environmernt 5.23 COM, DCOM, CORBA, RMI COM : Component Object Model, DCOM : Distributed COM (Microsoft) CORBA : Common Object Request Broker Archticture (Open Source) RMI: Remote Method Invocation (Java) 5.24 The COM software architecture is developed by Microsoft to build component-based applications. COM objects are discrete components, each with a unique identity, which expose interfaces that allow applications and other components to access their features. Suite of technology services developed by The Open Group for creating distributed applications that run on different platforms. OSF (Open Software Foundation) 4

5 LDAP Security by Encryption LDAP : Lightweight Directory Access Protocol, a set of protocols for accessing information directories. OpenLDAP is the Open Source Version of LDAP LDAP should eventually make it possible for almost any application running on virtually any computer platform to obtain directory information, such as addresses and public keys. Encryption techniques are based on public and private key s. Examples: GPG (GNU Pretty Good privacy for files and ) SSL (Secure Socket Layer - on application level) TLS (Transport Layer Security - on application level) IPSec (IP Secure on IP level) SSH (Secure Shell protocol) 5.27 Opdracht bestudeer 15.8 t/m