Can't get SSH ProxyCommand to work (ssh_exchange_identification: Connection closed by remote host)

Question

I'm unsuccessfully trying to use SSH ProxyCommand to connect to a server via a jump box. My config is below, I'm running this command:

ssh 10.0.2.54 -F ssh.config Host x.x.x.x User ec2-user HostName x.x.x.x ProxyCommand none IdentityFile /Users/me/.ssh/keys.pem BatchMode yes PasswordAuthentication no Host * ServerAliveInterval 60 TCPKeepAlive yes ProxyCommand ssh -W %h:%p -q [email protected] ControlMaster auto ControlPersist 8h User ec2-user IdentityFile /Users/me/.ssh/keys.pem 

The result is simply:

ssh_exchange_identification: Connection closed by remote host 

How can I get this to work/troubleshoot the issue?

Thanks,

Answer 1

ControlPersist in combination with ProxyCommand is not effective and you miss ControlPath option. But it is not a problem here.

First of all, if you are using non-standard config file and you want it to be used even by the proxy command, you need to specify it even there. The -q option makes the connection quiet so you have no idea what is going on under the hood of the proxy command. LogLevel DEBUG3 option is quite useful.

This line:

ProxyCommand ssh -W %h:%p -q [email protected] 

needs to be (and you don't need the username as it is already specified above):

ProxyCommand ssh -W %h:%p -F ssh.config x.x.x.x 

You have also wrong order of parameters in your command:

ssh 10.0.2.54 -F ssh.config -vv 

needs to be:

ssh -F ssh.config 10.0.2.54 

as you can read from manual page. And -vv is not needed if you use LogLevel option.

Then it should work for you (at least it did for me, otherwise investigate the log).