Intel® DevCloud
Help for those needing help starting or connecting to the Intel® DevCloud
1470 Discussions

Can't connect: Protocol mismatch



  I followed the recipe to connect to devcloud through my pre-installed cygwin environment, but I can't get into devcloud. When I run the "ssh devcloud+proxy" I end up with the terminal blocked and when I hit return, ssh shows "protocol mismatch" and then I have to kill it through CTRL+C.  Any idea on what might be wrong and/or how to fix this?




$ ssh -v devcloud+PROXY
OpenSSH_8.1p1, OpenSSL 1.1.1d  10 Sep 2019
debug1: Reading configuration data /home/xyz/.ssh/config
debug1: /home/xyz/.ssh/config line 257: Applying options for devcloud+PROXY
debug1: Executing proxy command: exec nc -x 22
debug1: identity file /home/xyz/.ssh/devcloud-access-key-42705.txt type -1
debug1: identity file /home/xyz/.ssh/devcloud-access-key-42705.txt-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_8.1
debug1: Remote protocol version 2.0, remote software version OpenSSH_7.4
debug1: match: OpenSSH_7.4 pat OpenSSH_7.0*,OpenSSH_7.1*,OpenSSH_7.2*,OpenSSH_7.3*,OpenSSH_7.4*,OpenSSH_7.5*,OpenSSH_7.6*,OpenSSH_7.7* compat 0x04000002
debug1: Authenticating to as 'guest'
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: MAC: <implicit> compression: none
debug1: kex: client->server cipher: MAC: <implicit> compression: none
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:A43Fccb1iM4pDwsT5OgjszJYHAJdaMmA4fV2hf1HmVo
debug1: Host '' is known and matches the ECDSA host key.
debug1: Found key in /home/xyz/.ssh/known_hosts:70
debug1: rekey out after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: rekey in after 134217728 blocks
debug1: Will attempt key: /home/xyz/.ssh/devcloud-access-key-42705.txt  explicit
debug1: SSH2_MSG_EXT_INFO received
debug1: kex_input_ext_info: server-sig-algs=<rsa-sha2-256,rsa-sha2-512>
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic
debug1: Next authentication method: publickey
debug1: Trying private key: /home/xyz/.ssh/devcloud-access-key-42705.txt
debug1: Authentication succeeded (publickey).
Authenticated to (via proxy).
debug1: Local connections to LOCALHOST:4022 forwarded to remote address c009:22
debug1: Local forwarding listening on ::1 port 4022.
debug1: channel 0: new [port listener]
debug1: Local forwarding listening on port 4022.
debug1: channel 1: new [port listener]
debug1: channel 2: new [client-session]
debug1: Requesting
debug1: Entering interactive session.
debug1: pledge: proc
debug1: client_input_global_request: rtype want_reply 0
debug1: Remote: Forced command.
SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3

Protocol mismatch.

debug1: client_input_channel_req: channel 2 rtype exit-signal reply 0
debug1: client_input_channel_req: channel 2 rtype reply 0
^Cdebug1: channel 2: free: client-session, nchannels 3
debug1: channel 0: free: port listener, nchannels 2
debug1: channel 1: free: port listener, nchannels 1
Connection to closed.
Transferred: sent 2712, received 2628 bytes, in 14.6 seconds
Bytes per second: sent 185.7, received 180.0
debug1: Exit status -1


0 Kudos
3 Replies


We tried connecting Devcloud through the Cygwin environment and it's working fine for us. Could you please follow the below steps.If you have done already,skip that step.

Step 1: Download CYGWIN: 64 bit version from   and run the setup with the --no-admin option. 
For more information on installation, please go through:      Note: If you have installed it already, skip to the next step.
Step 2: Open the Cygwin Terminal and set up SSH tunneling as described below for connecting to Intel AI Devcloud.

  • Download and save the SSH access key for Linux/macOS to the folder ~/Downloads/ on your computer and remove the ".txt" extension from the key name. Create the directory ~/.ssh, unless it already exists and copy the key file devcloud-access-key-XXXXX to ~/.ssh.       
     mkdir -p ~/.ssh
     mv ~/Downloads/devcloud-access-key-<user> ~/.ssh/
  • Create a config file in ~/.ssh folder. For that add the following lines in ~/.ssh/config file.
    Host devcloud_proxy
    User uXXXXX
    HostName c009
    Port 4036
    IdentityFile "<path to>/.ssh/devcloud-access-key-XXXXX"
    ProxyCommand ssh -T devcloud-socks-proxy
    Host devcloud-socks-proxy
    User guest
    IdentityFile "<path to>/.ssh/devcloud-access-key-XXXXX"
    LocalForward 4036 colfaxserver:22
    ProxyCommand nc -x %h %p 
  • Connect to devcloud:

      ssh devcloud_proxy

Hopes this helps. Please feel free to reach out to us if you have any issues.




0 Kudos


Could you please confirm whether you are able to connect Devcloud through Cygwin with the solution provided.

0 Kudos


We are closing this case by assuming that your issue got resolved. Please feel free to raise a new thread if you have any further issues

0 Kudos