Find a host with specific IP address.

Hi
I got a very large network about 5000 users and I need to find a host where it’s located I only have ip address how can I find the host or the switch host is connected to.
Please advice
ciscosuppAsked:
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Ken BooneConnect With a Mentor Network ConsultantCommented:
So what you can do is login to the layer 3 default gateway devices.  Most likely a set of core switches in a network that size.  From there ping the ip address in question.  If you can ping it from the core switch, you can then look in the core switch's arp table.

For instance you ping 10.100.1.5

Then issue this command

show arp | i 10.100.1.5

If you successfully pinged it from the layer 3 device that is on that network, the arp table will show you the mac address.

Once you have the mac address you can issue this command:

show mac address-table address xxxx.xxxx.xxxx

where xxxx.xxxx.xxxx is the mac address.  This will show you what port that mac address is being learned on.  At first this will probably be a port that another switch is connected to.  If so go to that switch and enter the same command.  Do that until you get to the final switch, and then the result will be the port that that device is on.

Hope that helps.
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Giovanni HewardCommented:
You can resolve addresses to hostname via ping, tracert, or nslookup (among others):

ping -4 -a -n 1 192.168.1.1

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tracert -4 192.168.1.1

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nslookup 192.168.1.1

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Use trace route to determine the nearest hop to the target IP address.  If you have access to that hop (e.g. router, switch stack, etc.), you can obtain the MAC address.  Use the MAC to identify the port.  Also with the MAC, you can determine the manufacturer of the NIC ( though this may be easily spoofed) via IEEE OUI lookup.  Once you have the port you can trace the line.

http://standards.ieee.org/develop/regauth/oui/public.html

If you use Cisco switches with CDP enabled, it's possible you could run this script I wrote on the target PC, to self-identify and report it's port.  Modify 127.0.0.1\c$ to reflect a central share.

@echo off
setlocal enabledelayedexpansion
rem Requires WinDump @ http://www.winpcap.org/windump/install/
rem        + WinPcap @ http://www.winpcap.org/install/default.htm
rem   OR
rem          TCPDUMP @ http://www.microolap.com/products/network/tcpdump/
echo Cisco CDP Port-ID Identifier v1.0 by Giovanni
set app=windump
set output=\\?\UNC\127.0.0.1\c$\PortID.txt
for /f "tokens=4" %%i in ('route print -4 0.*^|find "0.0.0.0"') do (
	if not [%%i]==[Default] (
		for /f "tokens=3 delims=," %%s in ('wmic nicconfig get IPAddress^,SettingID /format:csv^|findstr "%%i"') do (
			for /f "delims=." %%i in ('!app! -D^|findstr "%%s"') do (	
				!app! -i %%i -nn -v -s 1500 -c 1 ether[20:2] == 0x2000 | findstr "Device-ID Address Port-ID Platform"
			)>!output!
		)
	)
)
if exist !output! type !output!

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Additionally, you can scan the IP address using a port scanner (such as Nmap) in an attempt to identify services and banners, to further identify the system.

nmap -sS -sU -T4 -A -v -Pn 192.168.1.1

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ciscosuppAuthor Commented:
thanks for info.
How can i find the mac address when i only have ip
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Giovanni HewardConnect With a Mentor Commented:
You can check your ARP table, after initiating communication to the target IP.
arp -a|find "192.168.1.1"

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If that fails you'll need to read and follow the instructions above.
Use trace route to determine the nearest hop to the target IP address.  If you have access to that hop (e.g. router, switch stack, etc.), you can obtain the MAC address.

If you have access to the nearest hop, provide the make/model of the router and we can provide the commands to issue on the router to identify the MAC address and port.
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ciscosuppAuthor Commented:
thanks guys
:-)
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