IP Configuration command line Tool for windows (ipconfig)

Earlier versions of windows had “winipcfg” tool for performing ip configuration activities. “winipcfg” was replaced by “ipconfig” windows IP configuration tool from windows XP onwards. It is used to display the TCP/IP network configuration values.

To run it, enter “ipconfig” in the command prompt. This will display your IP address as follows:

In case your computer is part of a LAN using a router, the IP displayed by this command will be your Computers IP on the LAN and not the IP that connects to teh internrt. To obtain the IP address of your LAN on internet, you can try any DSL Reports whois.

The IP given is the local address on the network. This information can be used in diagnosing network problems. The “gateway” or router address on the local network is also displayed by this command.

Various switches that can be used with IPConfig

ipconfig switches can be invoked by entering “ipconfig /{switch}”. To display a list of all available switches, enter “ipconfig/?” or “ipconfig -?”. The most commonly used switches by a home user are :

•  all – to display a detailed ip configuration you can use ipconfig/all
• release- to release your IP address.
• renew – asking your network adapter to renew your machine’s ip address
• flushdns- this switch is used to clear all DNS info

The above mentioned switches are very handy for trouble shooting your internet connection issues.

The command syntax is netstat [-a] [-b] [-e] [-n] [-o] [-p proto] [-r] [-s] [-v] [interval] A brief description of the switches is given in Table I below. Note that switches for Netstat use the dash symbol “-” rather than the slash “/”.

Netstat usefulness

It is a command-line tool, which is very useful to check the behaviour of your network. It allows you to check all aspects of TCP/IP. It also tells you what all connections your machine is making presently. You can also check if any virus, malware or other unwanted script is making connection to other harmful sources and stealing your information through this command.

Some examples of usage of netstat command for non-professional users are:

Checking connections

TCP and UDP connections and their IP and port addresses can be seen by entering a command combining two switches: netstat -an

This command displays protocol, the local address, the remote address, and the connection state along with port.

Table II. Description of various connection states

How to check for unwanted or risky connections?

If u doubt that there are unwanted malwares on ur system trying to establish risky connections. You can find out which programs are making connections with the outside world, we can use the command

netstat -b

Actually, it is better to check over a period of time and we can add a number that sets the command to run at fixed intervals. Also, it is best to create a written record of the connections that are made over some period of time. The command can then be written

netstat -b 5 >> C:\connections.txt

Note that as written, this command will run with five-second intervals until stopped by entering “Ctrl+c“, which is a general command to exit. (Some reports say that this can be fairly CPU intensive so it may cause a slower, single-core machine to run sluggishly. Note that the Process ID (PID) is given. This command can be combined with other tools such as Task Manager to analyze what executable files and processes are active and are trying to make Internet connections.