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Examining How the Great Firewall Discovers Hidden Circumvention Servers (2015)
- schoen 10y ago(2015)
- bdz 10y agoHere is the presentation from CCC 2015 https://www.youtube.com/watch?v=NgYdmRR7JtY https://www.youtube.com/watch?v=NgYdmRR7JtY
- kbmajor 10y agoReadable version without extraneous nonsense: http://conferences.sigcomm.org/imc/2015/papers/p445.pdf http://conferences.sigcomm.org/imc/2015/papers/p445.pdf
- nbevans 10y agoTor stopped working (with bridge) when I was there last month. It worked for a day or two then stopped working. It didn't matter how many times I refreshed my bridges list, it just wouldn't work. Luckily I provisioned an Azure VM in Hong Kong which I could access via RDP to keep access to GMail, Facebook etc.
- phw 10y agoHere's a summary that's a bit easier to digest: https://blog.torproject.org/blog/learning-more-about-gfws-active-probing-system https://blog.torproject.org/blog/learning-more-about-gfws-ac...
- gerdesj 10y agoI've never been anywhere near the GFW but I do find OpenVPN listening on 443/tcp and a few other ports (tcp and udp) on the outside quite handy for drilling through firewalls. It supports basic auth proxies but CNTLM is in the toolbox as well. Add in NAT and a few routing entries on other hosts. It also provides a simple way to detect a transparent MitM proxy. If OVPN fails to connect but an "unprotected" https connection gets through then the alarm bells go off and the presented SSL cert gets a serious examination. I keep a couple of thumbprints of known certs handy for this - the discipline of proper checking rather than a cursory glance at an image that the GUI throws up. I use readily available stuff but looking into the description of how the obfs protocols work in Tor I'm impressed and rather glad that my life or liberty doesn't depend on my efforts. When I get it wrong I simply lose access to BBC iPlayer or whatever. When someone who is having to take this rather more seriously gets it wrong, they might not get a chance to repeat their mistake.
- mikeash 10y agoThis sort of thing used to work, but doesn't anymore. The GFW is now smart enough to detect VPNs based only on the traffic they generate, not port numbers or other easily changed things. It's currently an arms race between VPN providers trying to mask their traffic and the firewall trying to uncover it, and the firewall is winning so far.
- pixl97 10y agoWhelp, that's pretty much it for the internet. Won't be long before many more governments are licensing and using this technology. The question is how long before supposedly 'free' governments start.
- lisivka 10y agoIt's easy to fix by mirroring their behavior: drop incoming connections from China until they drop their firewall.
- rahimnathwani 10y ago
- Scoundreller 10y agoA good time to TLS fingerprint your connections and get an idea of which client is probing your server. Probers might have their own unique TLS fingerprint. https://blog.squarelemon.com/tls-fingerprinting/ https://blog.squarelemon.com/tls-fingerprinting/
- KayEss 10y agoWe have a client's system that seems to get probed for this sort of thing. We keep seeing URLs like the following being requested: htttps://www.example.com/http://www.baidu.com/cache/global/img/gs.gif There are a number of variations including plain IP numbers and other URLs, like www.google.com being used. I guess at some point somebody accessed the site from China. EDIT: Just got another probe from 94.102.49.174 owned by Quasi Networks Ltd in the Seychelles.
- dylz 10y agoQuasi (aka Ecatel) is basically a den of ddos for hire, ddos, malware, botnet C&C, abuse reports ignored. Servers are in NL. Probably not China.