Connectivity
Connectivity and managing Your Comcast Business network
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Connectivity problems 2/19; SSH key exchange broken?

Yesterday we had problems with some HTTP(S) sites not loading, or loading slowly. We also had a very strange issue with SSH where we could connect to the server and the key exchange would happen, then communication would be severed between client and server. After diagnosing for a bit, we found everything worked normally when going through any other network than comcast. Luckily we have two ISP and disabled advertising our prefix to Comcast. The problems immediately cleared up. 

 

What is comcast doing at a Layer 7 level to interefere with SSH connections and HTTPS connections??

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Re: Connectivity problems 2/19; SSH key exchange broken?

Hello theBruce and welcome,

 

I can technically assure you that Comcast does not do anything at Layer 7 whatsoever. However, you might wants to login to your Comcast Gateway and make sure that someone did not inadvertently enable (by unchecking) Smart Packet Detection. This can exhibit the symptoms you described. Also, perhaps you need to check your Browser's connection to Trusted Sites, which can be another root cause of your symptoms. Lastly, have you made absolutely sure that SSH standard port 22 on your server and client is open and not being utilized via another port likes 443?!  

 

Hope this helps you out.

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Re: Connectivity problems 2/19; SSH key exchange broken?

Thanks Rich - Comcast is claiming routing issues last week that affected "most of their customers," but still not sure how that explains our particular weird problem.

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