ostu - determining ip address (by tony fortunato)

© 2008 www.thetechfirm.com

Wireshark Troubleshooting

Tony Fortunato, Sr Network SpecialistThe Technology Firm

How To Determine A Device’s IP Address


What are you talking about?

Many times I have some network equipment and its IP address wasn’t documented or documented incorrectly

Here’s how to use Wireshark to figure out what its IP address is In this example I actually have this issue with several Proxim MP.11 wireless

subscriber units


Setup

Ethernet

Ethernet

I suggest putting a hub in between since powering up the Proxim device may cause the PC to miss some packets as its Ethernet adapter initializes

Proxim Wireless MP.11 unit


What To Do

Its pretty simple, Start a capture Go to Statistics-> Endpoint Report and look for the devices’ Ethernet address

(Proxim in my example) Right Click on that address and Apply As Filter->Selected


Review Trace

The key here is to look for a GRATUITOUS ARP. 99.99% of all IP devices send out this specific ARP packet upon bootup

The ARP is used to determine if this device has a duplicate IP Address This can be seen in the ARP packet details since the Sender and Target IP is the

same


Results

Try to ping, then telnet or http to access the device


Wireshark Training - QuickStart

Tony Fortunato, Sr Network SpecialistThe Technology Firm

Thank you


For additional educational videos on Open Source Network Tools, please click on the following …

http://www.lovemytool.com/blog/ostu.html

LoveMyTool.com – Community for Network Tools