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    • Delete 27 August 2023
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    • New note by bobjonkman 3 August 2023
      From a few years ago... All gone now, and I promised $SPOUSE it would never come back. https://gs.jonkman.ca/attachment/221480
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      bobjonkman favorited something by clacke: I tried for over four decades to grow an impressive personality, but it was a lot of effort and not much payoff, so now I'm just trying to grow an impressive beard instead.
    • bobjonkman repeated a notice by clacke 3 August 2023
      RT @clacke I tried for over four decades to grow an impressive personality, but it was a lot of effort and not much payoff, so now I'm just trying to grow an impressive beard instead.
    • bobjonkman repeated a notice by clacke 27 July 2023
      RT @clacke did you watch Oppenheimer, the film about the moral implications of the things we create, starring an actor who also played a Gotham City psychiatrist who went insaneordid you watch Barbie, the film about the moral implications of the things we create, starring an actress who also played a Gotham City psychiatrist who […]
    • Favorite 27 July 2023
      bobjonkman favorited something by clacke: did you watch Oppenheimer, the film about the moral implications of the things we create, starring an actor who also played a Gotham City psychiatrist who went insaneordid you watch Barbie, the film about the moral implications of the things we create, starring an actress who also played a Gotham […]
    • New comment by bobjonkman 29 June 2023
      @steve Wait, you or Dr. Cooley are at Perimeter? Giving any public lectures? If so, I'll hop on my bike to attend! @Perimeter
    • bobjonkman repeated a notice by steve 29 June 2023
      RT @steve From jodi on Mastodon: I’m looking forward to meeting students at TRISEP 2023 being held @Perimeter!
    • New note by bobjonkman 8 June 2023
      Several other authors of software that accesses the Twitter API have come to that conclusion as well. When #Twidere, my phone app to access Twitter stopped accessing Twitter back in January I pretty much abandoned Twitter. I still check Twitter with its WebUI, less than once a week, but I no longer post or engage […]
    • Favorite 8 June 2023
      bobjonkman favorited something by steve: I finally had a chance to figure out why my social bridging software was no longer able to talk to Twitter. Indeed, it's because under Twitter's new leadership, python-twitter has been deemed as violating something in their terms of service. It says I can submit a ticket, but they make […]

Archive for November, 2009

Blacklists considered harmful

Posted by Bob Jonkman on 19th November 2009

The black hole that sucks up Internet Addresses

The black hole that sucks up Internet Addresses

BoingBoing points me to a Security Fix article by Brian Krebs called A year later: A look back at McColo on the after-effects of Real-time Blacklists (RBLs) that targeted formerly undesirable IP addresses:

The Internet community typically shuns networks known to harbor spammers and organizations that host malicious software and other nastiness, usually by including their numeric Internet addresses on “blocklists”. Many organizations configure their e-mail servers to reject messages from addresses included on one or more of these blocklists. A heavily blocklisted network quickly becomes unattractive to legitimate businesses, since any e-mail sent out of that network will most likely be refused by the intended recipients.

“The problem is once an address block gets so polluted and absorbed into all these blocklists, it’s difficult to get off all of them because there is no central blocking authority,” said Paul Ferguson, an advanced threat researcher at Trend Micro.

(“Blocklist” is a less pejorative term for “Blacklist”)

The problem is not with the (formerly) malicious site, nor with the keepers of the blacklists, or even the lack of a central blocking authority. The problem is with e-mail server admins or firewall admins who let some unpaid, unaccountable blacklist censor their incoming mail or access to Web pages.

A blacklist should be just one of the criteria used to weight the probability that an incoming e-mail message is spam, or that an http stream contains malware. When I use a blacklist I’ll take into account the blacklist’s opinion of an IP source, but I don’t want a blacklist deciding what I can or can’t receive.

It’s far more reliable to actually examine the content stream for spam or malware instead of relying on a third-party’s opinion of an IP address. Yes, this increases the transaction cost for managing spam and malware, but as these blacklist IP address areas increase there’s an ever greater chance of false positives.

Are you using blacklists? Still think they’re a good idea? Wait until your blacklist gets compromised. An attacker takes control of a blacklist, but doesn’t interfere with its regular operations. Instead, it selectively adds and removes addresses. What better way to impose a DoS attack than maliciously subscribing your target to a well-known blacklist? In fact, for the long con I can see an attacker setting up a blacklist site, and spending a year or two building a reputation. As long as system admins rely completely on that blacklist to block certain IP addresses, those system admins are vulnerable to the whims of the blacklist operator.

I also wrote about the role of blacklists in Blocking Port 25 Considered Harmful, just under a year ago.

–Bob.

(Flickr image “Black Hole” by he who shall used under creative commons license)

Posted in considered harmful, dnsbl | Comments Off on Blacklists considered harmful

Deep Packet Inspection considered harmful

Posted by Bob Jonkman on 13th November 2009

Ripe for Deep Packet Inspection

Ripe for Deep Packet Inspection

Michael Geist points us to a Sandvine report analyzing global broadband traffic.

Far more interesting than the data presented by Sandvine is the fact that Sandvine has any data to present at all. How did they get this stuff? Did they buy it from Bell and Rogers? Does their throttling equipment phone home? I don’t recall giving them permission to use my data.

They claim they’re not looking at data content. Maybe that’s true, maybe it’s not. But they’ve inspected deeply enough to know that we use more streaming applications than P2P, and more Bittorrent than Gnutella. As any data analyst knows, traffic analysis of data patterns gives as much information as the data itself. Why are they allowed to gather any of this data at all? None of their business what I use on my computer.

I’m sure Sandvine is making a hefty buck selling this report, or at least using it as evidence to sell more of their DPI equipment. They’re profiting from the the data that I didn’t give them permission to use. I think the Privacy Commissioner may want to look into this.

–Bob.

Posted in considered harmful, Deep Packet Inspection, privacy | Comments Off on Deep Packet Inspection considered harmful

 
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