As we mentioned in an earlier post, someone attacked our network earlier this morning. Although we blocked the attack, we’ve also been working to identify who attacked our network and why. We now know the answer, and we are almost positive that the problem won’t recur.
Beginning at 2:16 AM Pacific time this morning, we began experiencing a “distributed denial of service” attack aimed at our “flexo” Web server.
The attack used more than 2 Gbps of network bandwidth from several thousand different IP addresses. This is an extremely high amount of traffic, saturating even our network connections.
The problem caused most of our servers to become unreachable (or very slow) from the Internet.
We restored service to all servers except the flexo Web server at 2:59 AM (by getting our network providers to block all packets for certain IP addresses). We restored service to the flexo server at 3:29 AM (by getting them to identify and block specific characteristics of the attack).
All services are now operating normally, and all delayed incoming mail has been delivered.
We take reliability seriously. Unfortunately, this is by far the largest attack we’ve seen on our network in ten years. We sincerely regret and apologize for the impact this had on our customers.
At approximately 11:00 PM Pacific time this Saturday, May 2, the “bender”, “calculon”, “lrrr” and “hypnotoad” servers will be restarted. As a result, Web site and e-mail service for customers on those servers will be unavailable for approximately five minutes.
The “farnsworth” server was restarted at 11:45 PM Pacific time tonight, causing a brief 2 minute interruption in Web and e-mail service for customers on that server. Incoming mail was queued and delivered after the interruption.
We posted earlier about a problem affecting the elzar Web server. While we were investigating the cause of that, the same thing happened on another Web server, “calculon”, causing a separate outage for customers on that server from 2:34 PM to 2:43 PM Pacific time this afternoon.
During this period, Web sites on that server were unavailable and incoming e-mail was delayed. (The Web server was slow for about six minutes after it was restarted, too.)
On both servers, high disk and memory usage caused the load to skyrocket to the point where they effectively stopped responding.
The good news is that we have narrowed down the cause, so it shouldn’t happen again. A bug in one of our maintenance programs that runs on each server was almost certainly responsible. The bug has been fixed.
We sincerely apologize for this issue, and regret the inconvenience it caused for customers hosted on these servers. Other servers were not affected.
The “elzar” Web server experienced high load between 5.40 and 6.00 AM Pacific time this morning, April 15. This resulted in slow Web sites and some interruption of service. (Some e-mail activity was delayed, but no e-mail was lost.)
We sincerely apologize for this problem. We consider this type of failure to be unacceptable, and are looking into the cause of the problem so that we can take the appropriate steps to prevent it from happening again.
As we’ve already posted, some of our Web servers will be restarted tonight at 11 PM Pacific time.
We’re adding the “zapp” Web server to that list so we can replace a RAID array disk that caused a problem on that server earlier today.
Update: The maintenance was completed with less than five minutes of “downtime”.
The “zapp” Web server was unavailable between 3:43 and 3.53 AM Pacific time this morning, April 4. This resulted in an interruption of service for Web sites on that server. (Some e-mail activity was delayed, but no e-mail was lost.)
We sincerely apologize for this problem. We consider this type of failure to be unacceptable, and are looking into the cause of the problem so that we can take the appropriate steps to prevent it from happening again.
At approximately 11:00 PM Pacific time on Friday, April 3, the “flexo”, “mom” and “elzar” servers will be restarted. As a result, Web site and e-mail service for some customers will be unavailable for approximately five minutes.
No e-mail will be lost, of course; incoming mail will just be slightly delayed.
We apologize for any inconvenience this may cause. This maintenance is necessary to install an updated “kernel” on our servers, as described in an earlier post.
Update: We’re also going to include the “zapp” server in this maintenance to replace a disk in the RAID array.
Update 2: The maintenance was completed with less than five minutes of “downtime”.
The “flexo” Web server was unavailable between 9:54 and 10:02 PM Pacific time tonight, March 28. This resulted in an interruption of service for Web sites on that server. (Some e-mail activity was delayed, but no e-mail was lost.)
We sincerely apologize for this problem. We consider this type of failure to be unacceptable, and are looking into the cause of the problem so that we can take the appropriate steps to prevent it from happening again.
Update: The problem happened a second time on March 31 from 6:22 to 6:31 AM. However, the second incident gave our engineers enough details to determine the cause (which we’ve reported in a subsequent blog post), and we have made a technical change that will prevent it from happening again.
