1. TCP/IP Networking sections 13.2,3,4,5 Road map: TCP, provide connection-oriented service IP, route data packets from one machine to another (RFC 791) ICMP, provide low level support for IP including error message, routing assistance, debugging ARP, translate IP address to hardware address. UDP, provides “best effort” transmission, connectionless

3. Packets & Encapsulation Linux support, Ethernet, FDDI, token ring, ATM(Asynchronous Transfer Mode), wireless Ethernet and serial-line-based system. Packets consist of header and payload Packet header information contains –Source and destination address –Checksum –Protocol specific information

4. Link Layer Ethernet framing standard: DIX Ethernet II & IEEE 802.2 LLC SNAP Linux support Ethernet II Novell and Microsoft use 802.2 Ethernet packet with different frame types can not talk to each other. Speed : 10Mbps,100Mbps,1Gbps, 10Gbps Wireless networking IEEE 802.11 define framing and signaling for wireless links Speed: 11 Mbps (802.11b -practical 1-2 Mbps), 54Mbps- 802.11a

5. Maximum Transfer Unit (MTU) The maximum amount of data that a link-layer packet can carry (See table 13.2 page245) Problems Fragmentation: The process of splitting the packets for lower router mtu’s

6. Type of addresses Unicast : refers to a single host Multicast : refers to a group of hosts Broadcast : includes all hosts on the local network

7. Media Access Control (MAC) Layer 2 Size: 6 byte First 3 byte identify the manufacture of the hardware. Check http://www.iana.org/assignments/ethernet-numbershttp://www.iana.org/assignments/ethernet-numbers ifconfig -a The address is fixed, but you can change it in Linux (not good idea!) Map MAC to IP using ARP

8. IP address Layer 3 Size : 4 byte Format x.x.x.x, 192.168.1.1 Mapping address to names: 1-Static /etc/host 2-Domain Name Server (DNS)

9. IP Classes ClassRangeFormatNumber of hosts A 1.0.0.0 -127.255.255.255N.H.H.H2 24 -2 B 128.0.0.0-191.255.255.255N.N.H.H2 16 -2 C 192.0.0.0-223.255.255.255N.N.N.H256-2 D 224.0.0.0-239.255.255.255 Used for multicast E 240.0.0.0-255.255.255.255 Used for testing Special address: 127.0.0.1 loopback address (localhost) private internets: 10.0.0.0 - 10.255.255.255 172.16.0.0 - 172.31.255.255 192.168.0.0 - 192.168.255.255

10. Subnetting and netmask Subnetting: borrow bit from the host portion to the network portion Example: Network: 192.168.1.0 With out subnetting we have 254 host Class c, can manipulate with the last 8 bits Required : 28 users 28+2< 2 5 host 2 3 =8 networks

11. Network address bits added to network address host address 192. 168. 1. NNN HHHHH 000 00000 001 00001 010 : 011 : 100 : 101 : 110 : 111 11111 Address range: 192.168.1.1-192.168.1.30, network: 192.168.1.0, broadcast 192.168.1.31 192.168.1.33-192.168.1.62, network: 192.168.1.32 broadcast 192.168.1.63 Subnet mask 11100000  224 or /27 - All-0 and all-1 host are reserved - Perl script that help with binary arithmetic ftp.ocs.com.au - Palm pilot version www.ajw.com/ipcalc.htm

12. PORTS Ports specify a particular communication channel between two process 53 DNS 80 HTTP 20,21 FTP

13. Routing Routing is the process of directing a packet through hops to reach it’s destination Tcp/ip routing information takes the form of rules “to reach network A, send to machine C” Routing table stored in the kernel If no entry found for packet and there is no default route specified an icmp message “ network unreachable “ returned to the sender Use netstat –r to examine machine routing table netstat –rn to avoid DNS lookup To add route in Linux Add route –net x.x.x.x netamask y.y.y.y gw Route to loopback is added at boot time

14. ICMP Redirect IP protocol has no error-reporting or error-correcting mechanism IP protocol lacks a mechanism for host and management queries ICMP designed to compensate for IP deficiencies In Linux accept_redirect in the /proc controls the acceptance of ICMP redirects.