Client is unable to log in to an EX switch using SSH or Telnet.

When a client is trying to connect to an EX switch using Telnet or SSH, it might fail with the following error:

ssh_exchange_identification: Connection closed by remote host

There could be several reasons for this behavior; for example, missing or empty directory under /var/ , an RSA key not being generated, etc.

The following are some possible troubleshooting steps:

1. Make sure that SSH or Telnet is configured on the EX. If not, configure it using the following commands and commit:

   #set system services ssh
#set system services telnet

2. Check the logs messages for the following error: empty directory missing in /var .

   If you see this message, create a directory named “empty” by using following commands:

   >start shell user root :

Password : ----enter root password---

- % cd /var
- % mkdir empty

3. Try again. If it still does not work, a new RSA and keygen might need to be generated. Regenerate the RSA and DSA keys for SSH with the following commands:

   >start shell user root

% ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key

   You will see this message:

   Generating public/private dsa key pair.
/etc/ssh/ssh_host_dsa_key already exists.
Overwrite (y/n)? >>>select yes

%ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key
Generating public/private dsa key pair.
/etc/ssh/ssh_host_dsa_key already exists.
Overwrite (y/n)? >>>select yes

4. If the issue persists, open a case with your technical support representative.

2020-03-27: Article reviewed for accuracy; no changes required.