The SSH Server Host Keys are used by all applications that play the role of an SSH Server. Specifically the Command Line Interface (CLI) and Tunneling in Accept Mode. These Keys can be created elsewhere and uploaded to the device or automatically generated on the device.

If uploading existing Keys, take care to ensure the Private Key will not be compromised in transit. This implies the data is uploaded over some kind of secure private network.

WARNING: When generating new Keys, using a large Bit Size will result in a VERY LONG key generation time. Tests on this hardware have shown it can take upwards of:

2 minutes for a 512 bit RSA Key
5 minutes for a 768 bit RSA Key
15 minutes for a 1024 bit RSA key
10 minutes for a 512 bit DSA Key
30 minutes for a 768 bit DSA Key
70 minutes for a 1024 bit DSA key

Note that some SSH Clients require RSA Host Keys to be at least 1024 bits in size.