Click to edit Master subtitle style Chapter 17: Troubleshooting Tools Click to edit Master subtitle style

Chapter 17 Objectives The Following CompTIA Network+ Exam Objectives Are Covered in This Chapter: 4.2 Given a scenario, analyze and interpret the output of troubleshooting tools • Command line tools o ipconfig o netstat o ifconfig o ping/ping6/ping -6 o tracert/tracert -6/traceroute6/traceroute -6 o nbtstat o nslookup o arp o mac address lookup table o pathping 2

Protocol Analyzers Used to capture packets in their raw format as they cross the network. 3

Throughput Testers Work much like a protocol analyzer in that they measure the traffic seen on the network and can also classify the types of traffic that are eating up bandwidth 4

Connectivity Software Designed to allow you to make a connection to the machine, see the desktop, and perform any action you could perform if you were sitting in front of it. 5

Command Line Tools Most of us are running Transmission Control Protocol/Internet Protocol (TCP/IP) Version 4 on our networks these days so we absolutely need a way to test IP connectivity. We also need be able to test and verify IPv6 networks. Several utilities to verify TCP/IP function on Windows workstations for both IPv4 and IPv6 The utilities are fairly platform independent and most of them can now use both IPv4 and IPv6. 6

Command Line Tools traceroute / tracert Traceroute (trace for short) displays the path a packet takes to get to a remote device by using Time-To-Live (TTL) Time-outs Internet Control Message Protocol (ICMP) error messages 7

Command Line Tools ipconfig and ifconfig The utilities known as ipconfig (in Windows), and ifconfig (in Unix/Linux/Mac) will display the current configuration of TCP/IP on a given workstation Current IP address DNS configuration Windows Internet Naming Service (WINS) configuration Default gateway 8

Command Line Tools IPConfig Options Ipconfig /all Ipconfig /release Ipconfig /renew To release your current DHCP TCP/IP information in Vista, you must elevate your command prompt 9

Command Line Tools The ping Utility Ping is the most basic TCP/IP utility, and it’s included with most TCP/IP stacks for most platforms. In most cases, ping is a command-line utility, although there are many GUI implementations available. You use the ping utility for two primary purposes: To find out if a host is responding To find out if you can reach a host 10

Command Line Tools Address Resolution Protocol (ARP) The Address Resolution Protocol (ARP) is part of the TCP/IP protocol stack. Uses broadcasts to translate TCP/IP addresses to MAC addresses. The ARP table in Windows includes a list of TCP/IP addresses and their associated physical (MAC) addresses. The ARP table contains two kinds of entries: Dynamic Static The arp Utility (using “arp –a”) 11

Command Line Tools The nslookup Utility A command-line utility that allows you to perform a single DNS lookup for a specific entity. The nslookup utility comes with Windows NT and later, as well as most versions of Unix and Linux, but not with Windows 95/98. It is run from a Windows command prompt. At the command prompt, you can start the nslookup utility by typing nslookup and pressing <enter>. 12

Command Line Tools The Mtr Command Mtr or My traceroute is a computer program that combines the functions of the traceroute and ping utilities in a single network diagnostic tool. Mtr is great if you have Linux or Unix, but by default, it’s not installed on Windows devices. Third-party applications of Mtr are available to install on Windows Microsoft includes its own version of Mtr called pathping 13

Command Line Tools The Route Command The route command is used to employ both static and default routing on Windows Vista and Server 2008 14

Command Line Tools The nbtstat Utility Microsoft Windows uses an interface called Network Basic Input/Output System (NetBIOS) relating names with workstations It is an upper-layer interface that requires a transport protocol—usually, TCP/IP, but IPv6 can be used as well. Deploying the nbtstat utility will achieve these three important things: Track NetBIOS over TCP/IP statistics Show the details of incoming and outgoing NetBIOS over TCP/IP connections Resolve NetBIOS names 15

NBTStat The nbtstat –a command: 16

NBTStat The nbtstat –c command: 17

NBTStat The nbtstat –n command: 18

NBTStat The nbtstat –r command: 19

NBTStat The nbtstat –S command: The nbtstat –s command: The nbtstat –s command produces the same output as nbtstat –S except it will also attempt to resolve remote-host IP addresses into host names. 20

Command Line Tools The netstat Utility netstat is a great way to check out the inbound and outbound TCP/IP connections on your machine. Packet statistics like how many packets have been sent and received, the number of errors, etc. can be viewed. 21

NetStat The netstat –a command: 22

Command Line Tools File Transfer Protocol (FTP) FTP has become a cross-platform protocol for transferring files. Windows TCP/IP stack includes a command-line ftp utility. To start the ftp utility, enter ftp at a command prompt. The result is an ftp command prompt: To display a list of all the commands you can use at the ftp command prompt, type help or ? and press <Enter> 23

Command Line Tools The Telnet Utility Part of the TCP/IP protocol suite, Telnet is a Terminal Emulation program designed to be used over the network telnet allows you to make connections to remote devices, gather information, and run programs. Telnet was originally developed to open terminal sessions from Unix workstations to Unix servers. 24

Command Line Tools Don’t Use Telnet, Use Secure Shell (SSH) Telnet is totally unsecure Telnet sends all data in clear text including your name and password. It has to be really bad thing these days; consider Microsoft doesn’t even enable it on their latest Oss (you know it really must be unsecure) SSH is the tool to use. SSH provides the same options as Telnet, plus a lot more It doesn’t send any data in clear text Your servers, routers, and other devices need to be enabled with SSH. SSH is not configured by default on most devices. 25

Summary Summary Exam Essentials Section Written Labs Review Questions 26