TCP/IP Fundamentals

Ch10

IPv4 Addressing

• Dev by DoD • IPv4 1980• Four Octets (8-bit/1 byte values) range from 0-

255• Address has two parts– network number– host number

Network Class

• Class, 1st Octet, Network Octets, Number of Networks, Network Size, Host Octets• Class A, 1-127, 1, 127 Networks 16M Host, 3• Class B, 128-191, 2, 16K Networks, 65K Host, 3 • Class C, 192-223, 3, 2M Networks, 254 Host, 1• 192.168.#.# - Class C• 172.16-31.#.# - Class B• 10.#.#.# - Class A

Related Technologies

• ICS Internet connection sharing• NAT Network address translation– Greatly Elongated life of IPv4

• Default Gateway Address• ipconfig• ipconfig/all

DNS• DNS Domain Name System Domain Name Service Domain Name

Server• Maps names (google.com) to ipaddress (cannot remember)• ICANN • Internet Corporation for Assigned Names and Numbers• www.icann.org• Assigns IP address to names though registrars• History:• InterNIC Integrated Network Information Center• IANA Internet assigned Numbers Authority• US controlled

DNS structure and Operation

• Root (13 root level DNS servers): Root• Top level: .com .edu.gov.net. org• Second level: uwa.edu assigned by ICANN• Subdomains: mail.uwa.edu

DNS Process

• Query first Domain name server• Fetches from higher level domain name server• Result will be cached to speed future access

IP, TCP, UDP protocols

• Segments - TCP• Datagrams - UDP• Packets - IP• Frame - Data link

UDP Frame (aka Datagram)

• Source Port • Desination Port• Msg Length • Checksum• Data

TCP Frame (aka segment)• Source Port • Desination Port• Sequence Num• Ack Num• Offset• Flags• Window• Checksum• Urgent Ponter• Options• Padding• Data

IP Frame• Version• HDR Len• Svc Type• Tot Len• TTL• Protocol• HDR checksum• Source IP• Dest IP• IP options• Padding• Datagram Data

Ethernet Frame

• DA - Dest MAC• SA - Src MAC• Type• IP Header • Datagram • CRC Error check

Assigning IP addresses

• Static IP address - manually entered• Dynamic IP assignment• WINS Windows internet naming service• Dynamic DNS• DHCP Dynamic Host Configuration Protocol• dynamically assigns ip addresses from a pool• Addresses are leased and expire• Printers and servers need static IP addresses

Port numbers and Socets• IP address plus port number is a socket• Well known port numbers• 80 HTTP• 443 HTTPS• 20 FTP Data• 21 FTP control• 53 DNS• 22 SSH • 23 Telnet• 25 SMTP• 110 POP

Hint: Be able to name several of these!

IPv6

• classless addressing• IPv4 32 bit address IPv6 128 bit address• 64X10E30 times as many• IPSec built in• ND Neighbor discovery will replace ARP

eventually• IPv6 address may contain MAC address

ICMP Internet control Message Protocol

• ICMP Internet control Message Protocol

IPv6

• 8 units of 16 bits (4 digit hex)

802 MAC

• IPv4 uses 48 but Mac Address and IPv6 64 bits• 24 bit mfg ID • 24 bit unique ID• IPv^6 uses 40 bit Unique ID• FFFE stuffing• Not always tied to MAC

Address Types

• Global Address - Routed• Link Local Address - un routed• Unique Local Address - within LAN

Addressing modes

• Unicast - single address• multicast - multiple addresses• anycast - to interface

Loopback addresses

• IPv4 127.0.0.1• IPv6 ::1• Unspecified Address ::

Example

• Example: Outside world knows me as 199.88.23.102

• But locally (via ipconfig)• Ethernet adapter Local Area Connection:• Connection-specific DNS Suffix . : uwa.edu• IPv4 Address. . . . . . . . . . . : 172.25.30.58• Subnet Mask . . . . . . . . . . . : 255.255.255.0• Default Gateway . . . . . . . . . : 172.25.30.1

Subnet Mask

• Subnetwork • Host portion can be re-divided into

subnetwork• bitwise AND used to determine subnet• See chapter 11

Reserved IPv4 Addresses (private use, not on internet)

• 192.168.0.0 - 192.168.255.255 Class C• 172.16.0.0 - 172.31.255.255 Class B• 10.0.0.0 - 10.255.255.255 Class A

TCP/IP Troubleshooting• Netstat – reveal network connections and stats

– Try netstat –a• Nbstat – netbios connections and stats

– Netbios – WINS or lmhosts– Try nbstat/? Or nbstat/help

• Ping – just reply please (ICMP)– Ping6– Ping -6– Ping -4

• Tracert or traceroute – analyze “hop” times• ARP – IP to MAC translator

– Arp –a– Rarp – reverse tranlation (bootp)

• Nslookup - domain name to IP address– whois