Sunday, February 22, 2009

Plans, bit VI

...part of this story is based on the classic IT story "Server 54, Where are you?" from several years ago. This bit gets rather technical again. Please let me know how I'm going with the explanations - I'll make a network engineer of you all yet :)

Evan barged down the corridor like a madman, his heart racing. He couldn't explain why, but he felt like he was witnessing a murder - an organised murder. They wouldn't just turn a server off, would they? What if someone was using it? Some little old granny on her lunch break even? Someone always pays, with every outage, it's always the way, so who was going to pay for this one?

Right now, it looked like it was Steve who was paying.

Reaching the door to the server room, he fumbled at the keypad, mistyping twice (No, no, no, get it right, third time sets off alarms!) before finally gaining breathless entry to a room awash with warmth and the loud blast of ineffectual air conditioning. He frantically looked around the room to see if someone was in there, but saw noone. Checking behind the 15 suites of server racks confirmed, noone was around.

Which meant that noone had powered the server off. Which meant that someone had probably just blocked Steve's server's port. Which meant that Steve was still alive.

He grabbed at the nearest console computer, behind rack suite 14, and looked up the IP address of the server in the network's core router. Every network has a core, and in the core, each computer that has an IP address needs to correspond to another address - a hardware address - that tells the core where it specifically is in the network. The way it does this, is that each device throughout the network report to each other what hardware addresses they are connected to, so the entire network learns where each device is located. Evan was able to do this manually, by looking up the IP address for Steve's server, and by noting it's hardware address, he can then trace where in the network it is located by checking the hardware address list in each device in turn. In the server room, there is only one device which a server would be attached to, and that was the core switch. This made things a lot easier.

After scouring the switch's logs, he found what he was looking for: an entry where someone shut down an ethernet port quite recently - in fact within the last 10 minutes. Evan opened the port, and then tried to message Steve on the box. He couldn't - he needed the right software first, and you couldn't run it on a switch. He looked up the port number - 8/17 - and then went to the rack holding the core switch. He grabbed at the cable in the port, and started following it with his own hands. The cable disappeared under the raised mezzanine floor, so he painstakingly prised a tile up from the floor, followed the cable to the next tile, and began lifting that.

It was then that he heard the door open into the room.

"...but we must find this server and shut it down before it does something to our network, Mr Wendel..." Greggy was leading Evan's boss into the room. Evan couldn't see much from where he was, with a rack suite between him and the door entry, but he could hear plenty.

Ben Wendel was a generous man who liked to run everything by the book. He liked things to stay up as long as possible, and did not like taking devices down without paperwork explaining why, how, when, where, what phase of the moon was out, what the lead engineer was wearing today, etc. He had an air of importance about him - self-importance - that made you either feel glad he was on your side, or feel horrified at what you were about to deal with. Right now, Evan was feeling the latter.

"Greggy, mate, we can't just switch a box off willy-nilly. We've shut down the network, I've agreed to that because I'm worried about "RIDDLER"'s backups running right, but what if this box is running a function, or algorithm that's needed? We can't afford to terminate that function until we know who uses it." RIDDLER was the company's email server, and it needed to have lots of speed on it's connection to enable a large amount of traffic.

"We can and we need to, the box is spamming our messaging..."

"You said it was only on two machines, though? How does that affect RIDDLER, say?"

"Just trust me, I've found worse than I've already explained to you."

"I *can't* trust you. We have to think of this from a management perspective. What breaks and who screams when we turn it off. If it does what you say it does, then guaranteed, someone will miss it! Now come on, let's go find it."

Wendel and Greggy made straight for the rack Evan was hiding behind. Evan frantically looked for a way to make himself scarce and ducked down another aisle between rack suites. He was desperate - he needed to find Steve's server before they did. Remembering his not-so-wholesome past, he grabbed at another console and made a connection to his home server outside the company. Like many computer engineers, he ran his own server at home, usually using it to help test connectivity and conditions getting back into the company from the outside world. 

From this server, he jumped to a free box in Sweden that he knew, then jumped to another box in the USA. From the USA box, he had a couple of stored files he could use to do very desperate things to get Wendel and Greggy's attention. Evan launched a DoS attack, or a Denial of Service attack using a script on "his" USA server. His target was his own company. Ideally, he wanted to make his company really notice the problem in an effort to call Wendel and Greggy away. After launching his nasty attack, he shut down the console, turned and hid in the corner of the room, where he wouldn't be seen.

About two minutes later, Wendel's phone rang. "Hello, Ben Wendel speaking... Oh, buggerit. Okay, I'll be right up... SOC? Oh, yeah, I've got Greggy with me here right now... No, I'm not sure where Evan is. Okay, talk in a few minutes..." 

Wendel hung up the phone in disgust. "Greggy, we're needed. We've lost our websites, the outside world seems to have slowed to a crawl..."

"Oh, no."

"Oh, yes, and we'll need to get that new kid trained up as quickly as possible..." Their voices faded suddenly as the door closed behind them. Evan logged back on to his USA server, and terminated the DoS attack script. "Right, that's got rid of you two, now let's find me Skynet..."

Evan picked up the mezzanine tile where he left off and began tracing the cable further and further, lifting tiles up as he made his slow painful way across the machine room's floor, tracing the cable along to the next one, lifting it up and replacing the former each time, and so on along the bank of racks - surely it would run up into a rack soon? - until he ran out of tiles to lift. The cable dove toward the concrete floor under the mezzanine, and then disappeared under a large thick plaster wall. 

"Well that's interesting..." Evan wondered if something was going to go right today.

1 comment:

  1. Nice work :) Yeah your explanations were good, don't worry. I'm doing ICT for A level and I really think we should learn this stuff instead - it would be much more useful, lol

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