let say i have found this ip aaa.bbb.ccc.ddd
tell me the way i can take to to finf other person that using that same ip.
(like a search engine on mirc channel with keyword aaa.bbb.ccc.ddd)

Searching a nick by IP/hostname

If you know the IP address or hostname someone is using, you can try
the /who server query. In case you want to convert an IP to hostname,
you can use /dns <IP> and /dns <hostname> to do the same query
backwards. Note that people might be known either by the IP address or
hostname. The best way is to try both.

Send a /who query for hawking.pp.htv.fi
/who hawking.pp.htv.fi
Send a /who query for 192.168.12.34
/who 192.168.12.34
If the query is successful, you will see the who reply for visible
nicks using the machine hawking.pp.htv.fi for the first query and
nicks using the machine 192.168.12.34 for the second query. If there
are no visible nicks from hawking.pp.htv.fi or 192.168.12.34, the only
server message you will get is the End of WHO. The users are invisible
for all your /who queries if they don't share a channel with you and
they have the usermode +i set. Since most servers automatically set
usermode +i, that means that the big majority of IRCnet users is not
included in your searches.

there are some scripts which can find ips in a channel for you.... 
http://helpdesk.zaz.net/documents/events/ondns.php for a doc about it.
but i dont seem to be able to find the exact script. also, beware that
some scripts have viruses and its a good idea to look thru them.

so your best bet is to still be in the same channel as the person with
that ip, if not, you are probly out of luck, you could port scan said
ip address and find an open port to talk on, maybe an email server or
telnet or something of the like. thats what i'm really looking for is
a universal ip one way (incoming) text program sitting on ip addresses
so you can talk to people if you lose thier contact information.

good luck. -compn