Numerous sources are reporting that Rutracker and Rutor went down in the evening yesterday.
It is said that it can be a result of a possible DDOS attack and Rutracker is confirming the attack at their twitter account:
The message says about the DDOS attack happening today, September,6, due to which the forum is not accessible.
Some sources publish a twitter message of the user @bycod3e:
As it is supposed this group can be responsible for the sites being down.
Some other sources were saying earlier about ISP problems.
In the past both trackers had been already been warned and blocked for illegal content but after deleting some content that caused the problem went back online.
At the moment of my message both trackers' sites are down meanwhile the server at least of one of them (rutracker) is functioning and serving the torrents downloaded earlier.