Hi
Do you mean IP of currently logged in user? Or something else?

I haven't seen this feature actually and it would for sure be handy to IP block somebody via your cPanel or something, id suggest showing this in the admin amongst the unverified or unapproved.

i want find that an special user comes to site from where?

You can have this details with AWstats.

where is it?
is it an oxwall plugin?

it should be this. http://en.wikipedia.org/wiki/AWStats

Yes. If your hoster is using CPanel, you can maybe find in it.

Or use analytics google.

my host is direct admin
i have google analytics but how can i find ip of an user with username example with google analytics?

You cant that was in a response to awstats. You cannot find the ip of specific users as of yet :(

+1
The only solution to assocy an user with an ip has to be created by Oxwall.
External software can't use username of Oxwall

i was detected a way for this :
1- with phpmyadmin go to installed oxwall database > go to: ow_base_user table  and then go to wanted user's row! (you can search wanted user's username in this table for this work!)
2- on wanted user's row, click on edit and then find  joinIp field
3- copy joinIp value (it is unsigned!)
4- go to this  site,
5- in IP Address from integer section, paste joinIp value and click on convert button!

Now you have your wanted user's real ip and you can block he/she by the server or by watch dog plugin!