DOS, Backscatter, ATT and 4chan
If I’ve got the story straight, it goes something like this:
- 4chan.org is subject to a DDOS attack.
- 4chan attempts to block the DOS, and in the process, unintentionally DOS’s one or more of ATT customers.
- ATT ‘blocks’ 4chan.
- The world comes to and end.
Forget network neutrality, evil empires, Haliburton, black helicopters and aliens from area 51. Let’s try for a simple explanation, assuming that nobody is evil and everyone is incompetent. It’s speculative, but has the advantage of holding to Occams Razor far better than the other speculative explanations floating around.
- 4chan gets DDOS’d, presumably from spoofed IP addresses. For high profile sites, that’s a normal thing. For low profile sites with large address spaces (us), that’s a normal thing. The sun rises in the east, someone on the Internet gets DDOS’d from spoofed addresses. It’s been that way for a decade or so. Life goes on. Get used to it. If you think you can run a high profile site and not get DOS’d, they perhaps you need to rethink your career. Try accounting. Accountants rarely get DOS’d from spoofed addresses.
- 4chan responds by filtering packets. Unfortunately they appear to have filtered in a manner that sent ICMP destination unreachable or perhaps TCP RST or ACK packets back at the spoofed IP addresses. It’s called backscatter.
- One of the spoofed addresses is an ATT customer. From ATT’s point of view they see a DOS sourced from 4chan. They don’t know or care if it’s real or backscatter. ATT puts up with the DOS for awhile, weeks perhaps, and finally says screw it – null route the dumb SOB’s.
- The Internet panics, providing amusing news for what otherwise would have been a slow news weekend.
Let’s pretend you are an ATT operator or engineer.
If ATT’s ops had decided to follow up with the owner of the IP address, there is no reason the think they’d have got very far. Presumably someone like ATT is subjected to DDOS’s more or less continuously, so to expect them to follow up on every one is pretty unreasonable.
As of today, the IP address for the 4chan web server’s Whois points to a generic hosting provider with no rwhois. A PTR lookup ends in ‘Server Failed’. Even if they had followed up and tracked it back to 4chan, the whois for 4chan.org points at a generic Network Solutions phone number with no other useful information. Surfing to the IP would have worked, but the only contact info on the web site is a few e-mail addresses, and surfing to an unknown web site to see who owns it is pretty unsafe now days. There is no reason for them to think that 4chan is anything other than a mickey mouse, incompetently run BBS that’s badly hacked and originating a DOS against them. It’s not like they haven’t seen that a hundred times before. Back in the day when I though it would matter, I followed up on a thousand-odd hacked web servers that port scanned, DOS’d or tried to hack me. Twenty or so per day for a couple or more years. Trust me, it’s a bloody pain.
ATT’s network ops see a DOS from an IP address aimed at one of their customers. They null route it. It goes away. They move on to the next crisis.
That’s what I’d do, and that’s what I’ve done a hundred times over the last decade.
The 4chan crowd think they are famous, and in their own minds they no doubt are, but I’ll bet that the vast majority of network engineers don’t know or care who 4chan is or what it does. They didn’t have a clue who 4chan is until Monday am., when they saw themselves in the news.
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