hostKey

The RSA, ECDSA, or ED25519 private key to use for your SFTP-enabled server. You can add multiple host keys, in case you want to rotate keys, or have a set of active keys that use different algorithms.

Use the following command to generate an RSA 2048 bit key with no passphrase:

ssh-keygen -t rsa -b 2048 -N "" -m PEM -f my-new-server-key.

Use a minimum value of 2048 for the -b option. You can create a stronger key by using 3072 or 4096.

Use the following command to generate an ECDSA 256 bit key with no passphrase:

ssh-keygen -t ecdsa -b 256 -N "" -m PEM -f my-new-server-key.

Valid values for the -b option for ECDSA are 256, 384, and 521.

Use the following command to generate an ED25519 key with no passphrase:

ssh-keygen -t ed25519 -N "" -f my-new-server-key.

For all of these commands, you can replace my-new-server-key with a string of your choice.

If you aren't planning to migrate existing users from an existing SFTP-enabled server to a new server, don't update the host key. Accidentally changing a server's host key can be disruptive.

For more information, see Manage host keys for your SFTP-enabled server in the Transfer Family User Guide.