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    • New note by bobjonkman 20 November 2017
      And #RemoteHashtag following can be done by selecting the Atom/RSS feed for a tag on the remote server and adding it to "Settings, Mirroring, Feed URL". https://gs.jonkman.ca/attachment/25187
    • New note by bobjonkman 20 November 2017
      #Hashtag following is already built into !GNUsocial, just select the "Subscribe" button on http://yourinstance.example.org/tag/hashtag https://gs.jonkman.ca/attachment/25185
    • New note by bobjonkman 20 November 2017
      Good article! Can you linkify the resources you mention, eg. Tor, Tox, Riot, Briar?
    • Favorite 20 November 2017
      bobjonkman favorited something by bob: The Honey Bee Algorithmhttps://www.youtube.com/watch?v=elTfueXcYaU
    • Favorite 20 November 2017
      bobjonkman favorited something by silverwizard: ♲ @Liam O (liamosaur@twitter.com): If you're a pentester and don't have even a little bit of impostor syndrome, you probably have dunning-kruger syndrome instead
    • Favorite 20 November 2017
      bobjonkman favorited something by lain: @eal @roka first they came for cowsay, but i wasn't an ascii graphic of a cow usually used to view fortune messages...
    • New note by bobjonkman 20 November 2017
      This makes a number of excellent illustrations of why the entire PKI system is broken. 1) Browser vendors wield power out of all proportion to their contribution to PKI. The same SSL certs banned by browsers can also be used for e-mail, XMPP, PBXes, &c. 2) A rogue Certficate Authority can poison the entire PKI […]
    • New note by bobjonkman 20 November 2017
      Justification for cloud storage...
    • Favorite 20 November 2017
      bobjonkman favorited something by rtsn: Tonight I'm going to stockholm for a key signing party. Really looking forward to it. Building the web of trust! #pgp #crypto
    • Favorite 20 November 2017
      bobjonkman favorited something by tq: Dear new Mastodon users, please keep in mind: This is not birdsite! Here we are nice and gentle to each other, overwhelmingly so. This is a place for us to feel comfortable, to chill and talk to each other with respect and kindness.Let us all strive to keep it this […]

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 | No Comments »

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 | No Comments »

 
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