Actually the only trace is IP address. Knowing IP address you can get the country and provider.

To get the name of the person or company, you have to contact provider and ask about it. Provider can give you that info only after law-court's approval

For the hack attack hackers use proxies, that can't be traced.

So it is absolutely idiocy to tell that Kremlin hacked Estonian sites.

Cool. All the country teenagers pinged Estonian servers, so there seems to be some patriotic internet hooligans in Kreml too? Good news. Who was it I wonder... Young fat butted system administators, yard-keepers, secretary girls?
All the bases are withdrawn from Georgia. The peacekeeping units are held in Abkhasia and South Osetia.
Ukraine - the Russian fleet is located and uses the shore facilities in Crimea due to the agreement up to the 2017.

YouTube - Russian Skinheads on CNN