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I have been using Tor on Linux for at least 5 years, without a problem from within enterprise network. I have set Tor network like a year or two ago to only use 80 and 443 ports to get pass the enterprise firewall and to always use brides with Obfs4 proxy. Now I got into a problem of not being able to connect to Tor network.

Few days ago my Tor connection stopped working. I got information from reliable source that enterprise bought new specialized firewall and now it is using deep packet inspection on ports 80 (only allowing pure http) and 443 (only allowing pure https). The intention was to get rid of TeamViewer installations that are using ports 80 and 443 to bypass VPN server. To overcome this problem in Tor configuration wizard I have removed only use 80 and 443 ports to be used by Tor and my Tor connection was working fine up until now.

Now I can't establish Tor connection again. I got information from reliable source that enterprise is in next stage of filtering and has start fighting against using Tor network. I see for e.g. that web page https://torproject.org/ is not accessible from web browser anymore and I also can't establish Tor connection on non-80 or non-443 port. In Tor wizard I have set:

a) Does your ISP blocks or otherwise censor connections to the Tor Network? Yes.

b) Tor Bridges Configuration: "Connect with provided bridges". Transport type: obfs4

c) Does this computer needs to use a local proxy to access the Internet? No.

Tor connection is not working.

On e-mail bridges@torproject.org with Google Gmail account I have requested obfs4 bridges and got bridges returned. I have copied the bridges into Tor wizard into field "Enter custom bridges", but I still can't establish connection to Tor network using obfs4.

I have made another request to bridges@torproject.org and returned bridges I copied them again into Tor wizard also using obfs4 and still get no Tor connection. Tor wizard does gets frozen on "Establishing and encrypted directory connection".

Bellow are Tor logs (I have masked the date/time and IP addresses with x/y/z letters):

xxxx.y.zz xx:yy:zz.000 [NOTICE] DisableNetwork is set. Tor will not make or accept non-control network connections. Shutting down all existing connections. 
xxxx.y.zz xx:yy:zz.000 [NOTICE] DisableNetwork is set. Tor will not make or accept non-control network connections. Shutting down all existing connections. 
xxxx.y.zz xx:yy:zz.000 [NOTICE] DisableNetwork is set. Tor will not make or accept non-control network connections. Shutting down all existing connections. 
xxxx.y.zz xx:yy:zz.000 [NOTICE] Opening Socks listener on 127.0.0.1:9150 
xxxx.y.zz xx:yy:zz.000 [NOTICE] Bootstrapped 5%: Connecting to directory server 
xxxx.y.zz xx:yy:zz.000 [NOTICE] Bootstrapped 10%: Finishing handshake with directory server 
xxxx.y.zz xx:yy:zz.000 [WARN] Proxy Client: unable to connect to xxx.xxx.xxx.xxx:37666 ("general SOCKS server failure") 
xxxx.y.zz xx:yy:zz.000 [WARN] Proxy Client: unable to connect to yyy.yyy.yyy.yyy:49168 ("general SOCKS server failure") 
xxxx.y.zz xx:yy:zz.000 [WARN] Proxy Client: unable to connect to zzz.zzz.zzz.zzz:48607 ("general SOCKS server failure") 
xxxx.y.zz xx:yy:zz.000 [NOTICE] Closing no-longer-configured Socks listener on 127.0.0.1:9150 
xxxx.y.zz xx:yy:zz.000 [NOTICE] DisableNetwork is set. Tor will not make or accept non-control network connections. Shutting down all existing connections. 
xxxx.y.zz xx:yy:zz.000 [NOTICE] Closing old Socks listener on 127.0.0.1:9150 

I got information from reliable source that enterprise has implemented some anti-Tor solution in a way that every 30 minutes from firewall-provider they get update of new Tor entry points and Tor bridges IP addresses and firewall automatically blocks them. So whole process is automated, just like an anti-virus program downloads new definitions, firewall downloads new IP addresses of Tor bridges / entry points from firewall-provider.

Is there any way to establish connection to Tor network in this case?

Thanks

  • Yes, there are plenty of ways, the easiest is to use Meek. – cacahuatl Jul 22 '16 at 17:56
  • Yes, meek did the trick. – folow Jul 25 '16 at 18:29
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Yes, you need to use Pluggable transports. I do recommend ObfS3/4 and Meek, they're solving a plenty of problems like this.

  • 1
    Obfs3 and obfs4 did not work. But meek-azure did the trick and I can now access Tor from enterprise. Excellent. Thanks a lot. – folow Jul 25 '16 at 18:29
  • @folow My pleasure! I'm glad to help - feel free to ask further questions – Alexey Vesnin Jul 25 '16 at 22:56

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