Fredlug networking
- 1. The ABC of Linux Networking By Peter Larsen FredLug September 2012
- 2. Agenda ● Good old OSI 7 layers ● The IP Stack ● Networking Examples ● Commands ● RHEL/CentOS/Fedora networking ● Ubuntu/Debian anyone??
- 3. Good old OSI 7 layers Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 4. Physical Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 5. Data Link Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 6. Network Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 7. Transport Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 8. Session Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 9. Presentation Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 10. Application Layer Physical Data Link Network Transport Session Presentation Application Physical Link Physical Data Link Network Transport Session Presentation Application
- 11. The IP Stack ● Internet Protocol ● Implements the network stack ● Uses fewer layers than OSI (Application, Transport, Internet, Link) ● End-to-end Principle ● Robustness Principle ● Was built to withstand loss of nodes and not break the network
- 12. The IP Stack
- 13. The IP Stack
- 14. Networking Examples ● Physical Networks ● IP basic network ● IP Package ● Gateways
- 15. Physical Network
- 16. IP Network
- 17. IP Package
- 18. Gateways
- 19. Concepts IP Address Internet Protcol Address (xx.xx.xx.xx) MAC Address Media Access Control (xx:xx:xx:xx:xx:xx) Netmask Indicates which part of IP address is network address Network Address Nodes on the same network can talk to one another Node Address Every node must have a unique address in it's network Gateway System that can route traffic Switch/Hub Device to interconnect multiple wires into a network DNS Domain Name System – translates names into IP (or visa versa) DHCP Dynamic Host Configuration Protocol
- 20. Commands ● Commands to configure ● Commands to diagnose
- 21. Commands to configure ● ifconfig ● ip ● route ● arp ● system-config-network (rhel/Fedora) ● /etc/resolve.conf ● /etc/hosts
- 22. Commands to diagnose ● ip show / ifconfig ● route – display routes ● arp – display current ARP table ● host / dig ● ping / traceroute ● ethereal / wireshark
- 23. RHEL/CentOS/Fedora networking ● Easy way: system-config-network ● “Hard way”: /etc/sysconfig/network-scripts ● service network start|stop|restart ● ifup / ifdown ● Network Manager
- 25. Questions
Editor's Notes
- #5: Media, signal and binary transmission Examples: 802.11, USB, Bluetooth, RS-232 (wire spec and RF specs)
- #6: Physical Addressing The data link layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer. PPP, SLIP, PPTP etc. (Point to Point)
- #7: The network layer provides the functional and procedural means of transferring variable length data sequences from a source host on one network to a destination host on a different network (in contrast to the data link layer which connects hosts within the same network), while maintaining the quality of service requested by the transport layer ARP, IP, ICMP, IPsec .
- #8: The transport layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. The transport layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. TCP, UDP
- #9: The session layer controls the dialogues (connections) between computers. It establishes, manages and terminates the connections between the local and remote application. TCP is defined here.
- #10: The presentation layer establishes context between application-layer entities, in which the higher-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. If a mapping is available, presentation service data units are encapsulated into session protocol data units, and passed down the stack. TLS, SSL
- #11: The application layer is the OSI layer closest to the end user, which means that both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. DNS, FTP, SNMP, SMTP, DHCP, SSH etc.