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Re: [Full-disclosure] Gmail and China's GFW
- To: Cal Leeming <cal@xxxxxxxxxxxxxxxx>, Alien Chatter <feedalienscoffee@xxxxxxxxx>, Full Disclosure <full-disclosure@xxxxxxxxxxxxxxxxx>
- Subject: Re: [Full-disclosure] Gmail and China's GFW
- From: bk <chort0@xxxxxxxxx>
- Date: Mon, 21 Mar 2011 15:19:10 -0700
On Mar 21, 2011, at 1:43 PM, Cal Leeming wrote:
>
>
> On Mon, Mar 21, 2011 at 8:39 PM, bk <chort0@xxxxxxxxx> wrote:
>
> On Mar 21, 2011, at 10:52 AM, Alien Chatter wrote:
>
> > $ sudo iptables -I INPUT -m string --algo bm --hex-string
> > '|476f6f676c6520496e63311830160603550403140f6d61696c2e676f6f676c652e636f6d30819f30|'
> > -j DROP
> >
> > Try it, you will get a connection timeout:
> >
> > $ curl --connect-timeout 60 https://mail.google.com/
> > curl: (28) SSL connection timeout
> >
> > The same applies for Twitter, Facebook... Much more efficient than
> > DNS/IP blocking!
> >
>
> Because searching for a bytestring in payload generates so much less load
> than just overriding a DNS result at the recursive server (that users are
> forced to issue queries to) or a simply drop SYNs based on IP header value
> that routers/firewalls are optimized for...
>
> I think you forgot your coffee this morning. It's not just for aliens you
> know.
>
> --
> chort
>
> _______________________________________________
> Full-Disclosure - We believe in it.
> Charter: http://lists.grok.org.uk/full-disclosure-charter.html
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>
> I think what he meant by efficient, was that if their sites ever get
> re-numbered or more end nodes are added (which may or may not be that often),
> then this would still catch the connections.
>
> Imho, I think it'd be better to just have a script checking for it, but
> nether the less, it's a cute approach (albeit, probably not usable in a
> production environment).
It's "efficient" in that humans get to be lazy. It's not efficient as far as
hardware resource utilization.
--
chort
_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/