SPX. Applicatie laag

Inleiding computersystemen en netwerken deel 2

5.1


5.2

Applicatie laag

OSI-model

Presentatie laag Sessie laag Transport laag Netwerk laag

Netwerk afhankelijk

Datalink laag Fysieke laag

Hogeschool Utrecht / Institute for Information & Communication Technology



5.3


Mogelijke toepassingen van netwerken • • • • • • • • •

Protocollen An agreed-upon format for transmitting data between two devices.

Fileserver-systems Remote execution / log-on Distributed systems Resource sharing (printer, scanner) Document sharing (www) Mail Voice (radio, telefonie) Video .....

• • • • • • • • •



Novell, IPX / SPX

5.4

The Point-to-Point Protocol (PPP) Telnet IPX/SPX - Novell NFS RPC X-window Apple talk Netbeui ....


5.5


5.6

Eenvoudig MS-DOS netwerk (LAN)

IPX : Internetworking Packet Exchange SPX : Sequence Packet Exchange SPX ligt bovenop IPX en wordt dus ingekapseld in IPX!



1


5.7


TCP / IP

5.8

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 (OSI layers 5 through 7)

e.g. HTTP, FTP, DNS

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.


5.9

IP-header


5.10

IP-adres

waarden per octet liggen tussen 0 en 255




5.11


5.12

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

145.89

• 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


5.13

Eindadres

10.0.0.0

10.255.255.255

172.16.0.0

172.31.255.255

192.168.0.0

192.168.255.255

127.0.0.0

127.255.255.255

5.14

TCP-header

Niet routeerbare adressen Beginadres


loopback Het poortnummer is gekoppeld aan een bepaalde applicatie. Poort 80 wordt bijv. gebruikt voor http verkeer.




5.15

5.16

Protocol stack voor TCP/IP

UDP (Universal Datagram Protocol)

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)





5.17


5.18

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


5.19


5.20

IP versie 6 Internet Protocol next generation




5.21


5.22

RPC : Remote Procedure Call

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. Hogeschool Utrecht / Institute for Information & Communication Technology



5.23


5.24

COM, DCOM, CORBA, RMI

DCE : Distributed Computing Environmernt • • •

COM : Component Object Model, DCOM : Distributed COM (Microsoft) CORBA : Common Object Request Broker Archticture (Open Source) RMI: Remote Method Invocation (Java)

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) Hogeschool Utrecht / Institute for Information & Communication Technology


4


5.25

LDAP


5.26

Security by Encryption

LDAP : Lightweight Directory Access Protocol, a set of protocols for accessing information directories.

Encryption techniques are based on public and private key’s.

OpenLDAP is the Open Source Version of LDAP

Examples:

LDAP should eventually make it possible for almost any application running on virtually any computer platform to obtain directory information, such as email addresses and public keys.

• GPG (GNU Pretty Good privacy for files and email) • 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 15.10


5

SPX. Applicatie laag

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