Solving confusing ssh problems

Last night I was setting up my new Time Capsule and suddenly lost access to all my remote servers over ssh.

All I got was the following error upon connection ‘ssh_exchange_identification: Connection closed by remote host” and everything I searched around the web implied this was to do with too many connections to the server or incorrect reverse dns setup.

Neither or these issues applied to me and for a while I was stumped until it dawned on me that the Time Capsule had a much better NAT implementation it in with specific handlers for different protocols and I have all my servers configured to accepting incoming ssh connections on a non-standard port so as to reduce the number of ssh probe attacks.  Once I opened up a different port that isn’t used for other protocols by default it all burst back into life.

Hopefully, this will help someone who encounters the same problem in the future!

3 Responses to “Solving confusing ssh problems”

  1. Vladimir Jirasek says:

    Hi, I have exactly the same problem, having occurred suddenly 3 days ago. I had not done any updates to my Time Capsule. My SSH servers are running on a standard port and yet I get ssh_exchange_identification error when connecting. When I plug in directly to my broadband modem I cannot without a hitch.
    I am not sure how to resolve this!
    Any suggestions?

    • westi says:

      It could be your server it being hammered with ssh requests from other parties (failing to log in) and as such doesn’t have the resources available to let you connect.

  2. Vladimir Jirasek says:

    It was actually rather simple. I had openssh-blacklist package installed on my debian etch. My TimeCapsule WAN IP address got blocked. What confused me was then when I connected to ISP modem directly I could connect to my server. What I did not realise was that I was actually given different IP address. Problem solved now.



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