GEGeek's How To Series

02/08/08     The Command Line Part 4 - Networking and TCP/IP Tools

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The command line or command window has many tools available for diagnostics and just for gathering information about your systems

current networking environment.

ipconfig - Windows IP Configuration
This command gathers information concerning your current network parameters for your network. Below are its parameters.

Usually when I am asked to diagnose a problem the first thing I need to see is the current setup for the PC.

So I always issue the command ipconfig /all    It tells me how many adaptors I am working with and their current configuration.

Most likely you will be concerned with your "Local Area Connection".

Next in my effort to diagnose an issue I inevitably will try to ping someone. Below are the command line switches for ping.

Ping sends out a packet to a designated internet host or network computer and measures its response time. This way you can look for

dropped packets, a slow line, or o connection at all where there should be.

My favorite command when troubleshooting is ping -n 100 -l 1500 "ip address"  or   ping 216.109.112.135 -t    ( Yahoo.com )

The 1st command floods the network with 1500 packets and will ping the host 100 times and then stop.

The -t option will ping the ip address forever until you stop it. Ctrl-C to stop the ping.

Next is Tracert

Tracert shows the actual path between two computers on the Internet. This path is not a straight line but consists of numerous segments or

"hops" from one intermediate computer to another. Tracert shows each step of the path taken. Consequently if you have a broken network

with this command you can see exactly how far the packets travel down the line before they stop. Great troubleshooting tool!

Here's the tracert command in action. Tracing my packets to Yahoo.com.

Another command which is a combination of ping and tracert is pathping

Pathping will first list the number of hops required to reach the address you are testing and then send multiple pings to each router between

you and the destination. After that, it computes results based on the packets returned from each router.

Here's the results of my PathPing to Yahoo.

Another very popular command with admin troubleshooters is Netstat - Displays active TCP connections on your computer.

Netstat displays the active TCP connections and ports on which the computer is listening, Ethernet statistics, the IP routing table,

statistics for the IP, ICMP, TCP, and UDP protocols

Netstat commands are issued as follows:  netstat -ano     Play with all the parameters to see the different results.

Can come in handy when troubleshooting your network or looking for spyware. Usually spyware keeps an open TCP/IP port on your PC.

A handy command sometimes is the nslookup command.

Let's say on your network you know someone's ip address but not their dns server name.

Below we see that when I issue the nslookup command for 216.109.112.135 it yields the name Yahoo

What if you wanted to know your own dns server name or hostname. Use the hostname command as shown below.

As you can see I named my box Core2Duo

Hope this was informative

GEGeek