Network+ Guide to Networks 5 th Edition

1. Network+ Guide to Networks5th Edition Chapter 10 In-Depth TCP/IP Networking

2. IPv6 Addressing • IP next generation (IPng) • Replacing IPv4 (gradually) • IPv6 support • Most new applications, servers, network devices • Delay in implementation • Cost of upgrading infrastructure • IPv6 advantages • More efficient header, better security, better prioritization provisions, automatic IP address configuration • Billions of additional IP addresses

3. IPv6 Addressing (cont’d.) • Difference between IPv4 and IPv6 addresses • Size • IPv4: 32 bits • IPv6: eight 16-bit fields (128 bits) • IPv6: 296 (4 billion times 4 billion times 4 billion) available IP addresses • Representation • IPv4: binary numbers separated by period • IPv6: hexadecimal numbers separated by colon • IPv6 shorthand: “::” any number of multiple, zero-value fields

4. Figure 4-12 A virtual connection for the Telnet service Sockets and Ports • Processes assigned unique port numbers • Process’s socket • Port number plus host machine’s IP address • Port numbers • Simplify TCP/IP communications • Ensures data transmitted correctly • Example • Telnet port number: 23 • IPv4 host address: 10.43.3.87 • Socket address: 10.43.3.87:23

5. Table 4-3 Commonly used TCP/IP port numbers Sockets and Ports (cont’d.)

6. Host Names and DNS (Domain Name System) • TCP/IP addressing • Long, complicated numbers • Good for computers • People remember words better • Internet authorities established Internet node naming system • Host • Internet device • Host name • Name describing device

7. Domain Names • Domain • Group of computers belonging to same organization • Domain name • Identifies domain (loc.gov) • Associated with company, university, government organization • Fully qualified host name (jasmine.loc.gov) • Local host name plus domain name • Example: www.google.com • Top-level domain (TLD): com • Second-level domain: google • Third-level domain: www • ICANN established domain naming conventions

8. Table 4-4 Top-level domains

9. Figure 4-13 Example host file Host Files

10. Figure 4-14 Domain name resolution

11. Configuring DNS • Large organizations • Often maintain two name servers • Primary and secondary • Ensures Internet connectivity • Each device must know how to find server • Automatically by DHCP • Manually configure workstation TCP/IP properties

12. Telnet • Terminal emulation protocol • Log on to remote hosts • Using TCP/IP protocol suite • TCP connection established • Keystrokes on user’s machine act like keystrokes on remotely connected machine • Often connects two dissimilar systems • Can control remote host

13. FTP (File Transfer Protocol) • Send and receive files via TCP/IP • Host running FTP server portion • Accepts commands from host running FTP client • FTP commands • Operating system’s command prompt • No special client software required • FTP hosts allow anonymous logons • After connected to host • Additional commands available • Type help

14. TFTP (Trivial File Transfer Protocol) • Enables file transfers between computers • Simpler (more trivial) than FTP • TFTP relies on Transport layer UDP • Connectionless • Does not guarantee reliable data delivery • No ID and password required • Security risk • No directory browsing allowed • Useful to load data, programs on diskless workstation

15. PING (Packet Internet Groper) • Provides verification • TCP/IP installed, bound to NIC, configured correctly, communicating with network • Host responding • Uses ICMP services • Send echo request and echo reply messages • Determine IP address validity • Ping IP address or host name • Ping loopback address: 127.0.0.1 • Determine if workstation’s TCP/IP services running

16. Figure 10-7 SNAT (Static Network Address Translation) Address Translation • Public network • Any user may access • Little or no restrictions • Private network • Access restricted • Clients, machines with proper credentials • Hiding IP addresses • Provides more flexibility in assigning addresses • NAT (Network Address Translation) • Gateway replaces client’s private IP address with Internet-recognized IP address • Separates private, public transmissions on TCP/IP network

17. SMTP (Simple Mail Transfer Protocol) • Protocol responsible for moving messages • From one mail server to another • Over TCP/IP-based networks • Operates at Application layer • Relies on TCP at Transport layer • Operates from port 25 • Provides basis for Internet e-mail service • Relies on higher-level programs for its instructions • Services provide friendly, sophisticated mail interfaces

18. MIME (Multipurpose Internet Mail Extensions) • SMPT drawback: 1000 ASCII character limit • MIME standard encodes, interprets binary files, images, video, non-ASCII character sets within e-mail message • Identifies each mail message element according to content type • Text, graphics, audio, video, multipart • Does not replace SMTP • Works in conjunction with it • Encodes different content types • Fools SMTP

19. POP (Post Office Protocol) • Application layer protocol • Retrieve messages from mail server • POP3 (Post Office Protocol, version 3) • Current, popular version • Relies on TCP, operates over port 110 • Store-and-forward type of service • Advantages • Minimizes server resources • Mail deleted from server after retrieval • Disadvantage for mobile users • Mail server, client applications support POP3

20. IMAP (Internet Message Access Protocol) • More sophisticated alternative to POP3 • IMAP4: current version • Advantages • Replace POP3 without having to change e-mail programs • E-mail stays on server after retrieval • Good for mobile users

21. IMAP (cont’d.) • Features • Users can retrieve all or portion of mail message • Users can review messages and delete them • While messages remain on server • Users can create sophisticated methods of organizing messages on server • Users can share mailbox in central location • Disadvantages • Requires more storage space, processing resources than POP servers • Network managers must watch user allocations closely • IMAP4 server failure • Users cannot access mail

22. Figure 10-11 Output of a netstat – a command Netstat • Displays TCP/IP statistics, component details, host connections • Used without switches • Displays active TCP/IP connections on machine • Can be used with switches

23. Nbtstat • NetBIOS • Protocol runs in Session and Transport layers • Associates NetBIOS names with workstations • Not routable • Can be made routable by encapsulation • Nbtstat utility • Provides information about NetBIOS statistics • Resolves NetBIOS names to IP addresses • Useful on Windows-based operating systems and NetBIOS • Limited use as TCP/IP diagnostic utility

24. Hostname and Nslookup • Hostname utility • Provides client’s host name • Administrator may change • Nslookup • Query DNS database from any network computer • Find the device host name by specifying its IP address • Verify host configured correctly; troubleshoot DNS resolution problems

25. Traceroute • Windows-based systems: tracert • Linux systems: tracepath • ICMP ECHO requests • Trace path from one networked node to another • Identifying all intermediate hops between two nodes • Transmits UDP datagrams to specified destination • Using either IP address or host name • To identify destination • Command used a number of switches

26. Route • Route utility • Allows viewing of host’s routing table • UNIX or Linux system • Type route and press Enter • Windows-based system • Type route print and press Enter • Cisco-brand router • Type show ip route and press Enter • Route command • Add, delete, modify routes