Chapter 13: Troubleshooting network connectivity Unit objectives Identify TCP/IP troubleshooting tools Discuss the Telnet utility and its functions Discuss the functions the File Transfer Protocol (FTP) utility Diagnose a problem and choose the appropriate troubleshooting tools

Topic A Topic A: TCP/IP troubleshooting tools Topic B: Telnet Topic C: File Transfer Protocol Topic D: Troubleshooting examples

TCP/IP troubleshooting tools ARP HOSTNAME IPCONFIG WINIPCFG IFCONFIG NBTSTAT NETSTAT NSLOOKUP PING TRACERT ROUTE

ARP (and RARP) ARP supports All TCP/IP clients Helps a host to find – the MAC address of another host – on the same internetwork, – if appropriate host’s IP address is given RARP is used to find a host’s own IP address, when it’s own MAC address is known. – For a “network boot”.

TCP/IP Utilities Ping Traceroute or tracert Arp Netstat Nbtstat (NetBIOS names) Many more….

Ping

pinging

Tracert

Arp protocol Short for Address Resolution Protocol, a TCP/IP protocol used to convert an IP address into a physical address, such as an Ethernet address. A host wishing to obtain a physical address broadcasts an ARP request onto the TCP/IP network. The host on the network that has the IP address in the request then replies with its physical hardware address. There is also Reverse ARP (RARP) which can be used by a host to discover its IP address. In this case, the host broadcasts its physical address and a RARP server replies with the host's IP address. Webopedia.com

Arp functions

Arp

Netstat functions

Netstat –r

Netstat –n

Netstat –a

Netstat -e

Nbtstat (NetBIOS over TCP/IP) Functions

HOSTNAME Supports All TCP/IP clients Used to determine the local machine’s host name Just type “hostname” from a command prompt

IPCONFIG Supports Windows 98 and Windows NT/2000/Server 2003/XP platforms Displays the current IP settings for the system Used to renew or release IP addresses assigned by a DHCP server

WINIPCFG Supports Windows 95 and Windows 98 platforms Helps to obtain information about the system’s TCP/IP configuration

WINIPCFG

Activity A-1 page 13-6 \begin on Monday, 12-1 Discussing ARP, HOSTNAME, IPCONFIG, and WINIPCFG

IFCONFIG Supports UNIX platform Displays the current network interface setting for the system

NBTSTAT Supports Windows 95/98 and Windows NT/2000/Server 2003/XP platforms Helps to view and NetBIOS name cache information manage

NETSTAT Supports all TCP/IP clients Displays protocol statistics and current TCP/IP network connections

NETSTAT – an example

Another Example, my own PC C:\Documents and Settings\Administrator.NETVISTA> TCP netvista:27015 localhost:3636 ESTABLISHED TCP netvista:3846 a deploy.akamaitechnologies.com:http CLOSE_WAIT TCP netvista:3848 a deploy.akamaitechnologies.com:http CLOSE_WAIT TCP netvista:3849 a deploy.akamaitechnologies.com:http CLOSE_WAIT TCP netvista:3850 a deploy.akamaitechnologies.com:http CLOSE_WAIT TCP netvista:4835 an-in-f19.google.com:http ESTABLISHED TCP netvista:4852 static nyc20.tbone.rr.com:http ESTABLISHED TCP netvista:4853 a deploy.akamaitechnologies.com:http ESTABLISHED TCP netvista:4854 static nyc20.tbone.rr.com:http ESTABLISHED TCP netvista:4859 carepages.com o7.net:https TIME_WAIT TCP netvista:4861 a deploy.akamaitechnologies.com:http ESTABLISHED TCP netvista:4863 a deploy.akamaitechnologies.com:https ESTABLISHED TCP netvista: btnaccess.net:http ESTABLISHED TCP netvista:4889 carepages.com o7.net:https TIME_WAIT TCP netvista:4898 yx-in-f18.google.com:http ESTABLISHED TCP netvista:4899 yx-in-f18.google.com:http ESTABLISHED

Activity A-2 page 13-9 Discussing IFCONFIG, NBTSTAT, and NETSTAT

NSLOOKUP Supports all TCP/IP clients Retrieves information stored by the DNS server Is an industry standard used for obtaining information from a DNS server

DIG Used to support only UNIX clients, but has now been ported to the Windows platform as well Lets you retrieve information stored by the DNS server Doesn’t come with Windows Neither NSLOOKUP nor DIG will work with a workgroup; you have to be in a domain. Both NSLOOKUP and DIG examine the DNS server search process.

DIG – an example

PING Supports all TCP/IP clients Verifies connections to one or more remote computers

TRACERT Supports all TCP/IP clients Used to trace the route that a packet takes to reach the destination

TRACERT – an example

ROUTE Supports all TCP/IP clients Used to manage static routing tables

Activity A-3 page Discussing NSLOOKUP, DIG, TRACERT, PING, and ROUTE

Topic B Topic A: TCP/IP troubleshooting tools Topic B: Telnet Topic C: File Transfer Protocol Topic D: Troubleshooting examples

Telnet Supports dumb terminal connection and emulation with remote servers Telnet provides access through terminal emulation to any host running a Telnet daemon service Used for remote configuration of hubs and routers

Telnet utility on Windows NT/2000/XP/Server 2003 When TCP/IP is installed on a Windows NT/2000/XP/Server 2003 station, Telnet is added to the system

Troubleshooting with Telnet Telnet is a powerful diagnostic tool It provides a way of sending commands directly to a server process and viewing the results when higher-level protocols or applications appear to be failing

Activity B-1 page Discussing Telnet

Topic C Topic A: TCP/IP troubleshooting tools Topic B: Telnet Topic C: File Transfer Protocol Topic D: Troubleshooting examples

File Transfer Protocol File Transfer Protocol (FTP) transfers text and binary files between systems, including dissimilar platforms Performs a format and type conversion on the file Supports all TCP/IP clients Can be used interactively at the command prompt or in a script (batch) file

FTP commands help [command] quit or bye ascii binary get put

Activity C-1 page Discussing File Transfer Protocol

Topic D Topic A: TCP/IP troubleshooting tools Topic B: Telnet Topic C: File Transfer Protocol Topic D: Troubleshooting examples

Troubleshooting examples TCP/IP suite of utilities can be used to troubleshoot: – Routers – system – MAC address – Overlapping scopes

Activity D-1 Troubleshooting sample problems

Unit summary Identified TCP/IP troubleshooting tools Discussed the Telnet utility and its functions Discussed the functions the File Transfer Protocol (FTP) utility Learned to diagnose a problem and choose the appropriate troubleshooting tools