Daily Archives: 15 March 2018

When you try to connect via ssh on a domain for which you are using CloudFlare as a HTTP proxy, you will get the following error:

$ ssh [email protected]
 ssh_exchange_identification: Connection closed by remote host

You have a few options to resolve for this issue:

1. Either connect directly to the IP of the machine.
2. Or, setup a CNAME record with no HTTP proxy for the SSH (so that you do not need to remember the IP).
   This solution does not offer any additional benefits than connecting directly to the IP of the server.
   To do that, you need to visit the configure DNS page for your site: e.g. https://www.cloudflare.com/a/dns/example.com,
   then create the CNAME named ssh, use as target your domain (e.g. example.com) and disable HTTP proxy by clicking on the orange cloud and making it gray before pressing the Add Record button.
   
   Then, you will be able to connect via ssh [email protected].
3. Last solution but not least is configuring your server to listen for SSH on one of the ports of CloudFlare that are open.
   When this post was written, the following ports were available/open for any site in CloudFlare:
   For requests made via HTTP:

   80
   8080
   8880
   2052
   2082
   2086
   2095

   For requests made via HTTPS:

   443
   2053
   2083
   2087
   2096
   8443

   At the time, we were using an Ubuntu GNU/Linux server, to instruct Ubuntu SSHD to listen to multiple ports we edited the file /etc/ssh/sshd_config and right after the lines:

   # What ports, IPs and protocols we listen for
   Port 22

   we added another line with the new port we wanted to use:

   # What ports, IPs and protocols we listen for
   Port 22
   Port 2053

   After restarting the service
   service ssh restart;
   we were able to connect to our page as follows:
   ssh -p 2053 [email protected];