Ruby On Rails in UA/Программирование на ROR/Получение IP/RE: Получение IP

посомтри REMOTE_IP
http://api.rubyonrails.com/classes/ActionController/AbstractRequest.html#M000408

remote_ip()

Determine originating IP address. REMOTE_ADDR is the standard but will fail if the user is behind a proxy. HTTP_CLIENT_IP and/or HTTP_X_FORWARDED_FOR are set by proxies so check for these before falling back to REMOTE_ADDR. HTTP_X_FORWARDED_FOR may be a comma- delimited list in the case of multiple chained proxies; the first is the originating IP.