enigma-bbs/docs/_docs/servers/loginservers/ssh.md

layout	title
page	SSH Server

SSH Login Server

The ENiGMA½ SSH login server allows secure user logins over SSH (ssh://).

Configuration

Entries available under config.loginServers.ssh:

Item	Required	Description
privateKeyPem	👎	Path to private key file. If not set, defaults to ./config/ssh_private_key.pem
privateKeyPass	👍	Password to private key file. *
firstMenu	👎	First menu an SSH connected user is presented with. Defaults to sshConnected.
firstMenuNewUser	👎	Menu presented to user when logging in with one of the usernames found within users.newUserNames in your config.hjson. Examples include new and apply.
enabled	👍	Set to true to enable the SSH server.
port	👎	Override the default port of 8443.
address	👎	Sets an explicit bind address.
algorithms	👎	Configuration block for SSH algorithms. Includes keys of kex, cipher, hmac, and compress. See the algorithms section in the ssh2-streams documentation for details. For defaults set by ENiGMA½, see core/config_default.js.
traceConnections	👎	Set to true to enable full trace-level information on SSH connections.

• IMPORTANT With the privateKeyPass option set, make sure that you verify that the config file is not readable by other users!

Example Configuration

{
    loginServers: {
        ssh: {
            enabled: true
            port: 8889
            privateKeyPem: /path/to/ssh_private_key.pem
            privateKeyPass: sup3rs3kr3tpa55
        }
    }
}

Generate a SSH Private Key

To utilize the SSH server, an SSH Private Key (PK) will need generated. OpenSSH or (with some versions) OpenSSL can be used for this task:

OpenSSH

ssh-keygen -m PEM -h -f config/ssh_private_key.pem

Option descriptions:

Option	Description
-m PEM	Set the output format to PEM, compatible with the ssh2 library
-h	Generate a host key
-f config/ssh_private_key.pem	Filename for the private key. Used in the privateKeyPem option in the configuration

When you execute the ssh-keygen command it will ask for a passphrase (and a confirmation.) This should then be used as the value for privateKeyPass in the configuration.

OpenSSL

If you do not have OpenSSH installed or if you have trouble with the above OpenSSH commands, using some versions for OpenSSL (before version 3) the following commands may work as well:

openssl genpkey -algorithm RSA -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:65537 | openssl rsa -out ./config/ssh_private_key.pem -aes128

Or for even older OpenSSL versions:

openssl genrsa -aes128 -out ./config/ssh_private_key.pem 2048

Note that you may need -3des for very old implementations or SSH clients!

Prompt

The keyboard interactive prompt can be customized using a SSHPMPT.ASC art file. See art for more information on configuring. This prompt includes a newUserNames variable to show the list of allowed new user names (see firstMenuNewUser above.) See mci for information about formatting this string. Note: Regardless of the content of the SSHPMPT.ASC file, the prompt is surrounded by "Access denied", a newline, the prompt, another newline, and then the string "[username]'s password: ". This normally occurs after the first password prompt (no art is shown before the first password attempt is made.)