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Sun, 07 Sep 2008Oh poor blog. You are neglected and ignored. I have a confession to make, blog: I am cheating on you with another blog I write (invite only). But don't you worry seattlewireless.net, I am going to start backfeeding/cross posting all my content onto this blog too, so the internet at large can read what I have been up to (for better or for worse). Oh, and I have very depressing news. I really wanted to do another mail bag, but frankly, nobody emails me anymore. Maybe they read the public scathing unleashed in my last (and only) mailbag. Fri, 22 Dec 2006Our electricity came on Thursday evening at 4 PM, making this power outage exactly 7 days long. This last week I have been living a double life. 21st century network engineer by day, but I had to set my clock back 200 years when I got home. Away from the world of electricity, multi-billion bit per second optical communication links, prepetual warmth and food and into the land of kerosene lamps, wood fires, firewood chopping, nestling pots in the coals to make tea and coffee, and pitch black nights. Temperatures plunged into the mid-twenties during the evening, making them very cold nights. Even with this low temperature, I found my garage freezer at a balmy 50-55F earlier this week. Inside this freezer was many pounds of rotting whale, caribou, and salmon. The smell is quite....interesting? Over the last week, the line of light and dark has been progressively moving closer towards my house. The scene was always unreal. At the end of electrical service started thick, dark clouds of smog (wood fireplaces), the distant hum of what sounded like 20 lawnmowers (gas generators), and electrical wires and other damaged pieces of civilization strewn about the streets that nobody has bothered to even fix. I was not alone either. Many people at the office, which is based on the "east side" in Bellevue, were and still are in this situation. There have been many power outages much longer than this in the history of electrical service, but I can tell you that a few days is a very, very long time for the ill prepared. The funny part is, my wife and kids do this for fun when we go backpacking. We didn't really mind it all that much, as we were planning on going camping soon this winter anyways. Tue, 20 Apr 2004
RST
This is not a new exploit, but something as of late has pushed Cisco and other vendors to secure critical infrastructure (BGP Routing). Its about time too, since these initial warnings date back several years. The push to do it now was either caused by some existing code in the wild, or increasing concerns from the goverment. By using MD5 digests within TCP Header Options, this keeps BGP peers from being vunerable to stuff like spoofed TCP resets. This MD5 system provides connectionless security, not just in the payload, like SSL for example. This RST exploit in particular involves 3 hosts, 2 of which have an active TCP connection, and 1 rouge host. The rouge host transmits a series of TCP RST packets, scanning a sequence number range and a guessed source port range. Most of these resets are discarded by the receiver's stack. Once the reset packet is what the receiver's stack expects as the next packet, it immediately disconnects the session. Another interesting thing to note about the sequence number is that it is not an exact value, but a variable sized range, dependant on the window size. We are talking a greater possibility than just 2^32. This makes long term, large window TCP connections the most vunerable. A window size of 32768 reduces the probability to about 1 in 100,000. This is especially dangerous because it does not take a long time to send this amount of information. Its not too difficult to guess the initial sequence number (ISN) of a TCP connection on IOS, check this out. You could then try to inject routes, but it would be very difficult. BGP does not particularly like its sockets being repeatively broken, and if done on a wide scale, it could cause instability of the internet. Fri, 16 Apr 2004
Heh, looks like a lot of providers are BCC'ing entire internet exchange
Cisco BGP Exploit?
Md5 authentication? BGP config changes? Sounds like random hosts can pretend they are bgp peers and inject random routes or cause some sort of mayhem. If i actually knew what it was, i'd talk about it, but I am discovering how high our company is on Cisco and our ISP's priority list. Mon, 05 Apr 2004
Drunk Engineer's Party Foul Turns Into Engineering Breakthrough
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