AMX NXA-ENET24 Instruction Manual page 221

1. Generate a Host Key Pair – Use the ip ssh crypto host-key generate command to create a host
public/private key pair.
2. Provide Host Public Key to Clients – Many SSH client programs automatically import the host
public key during the initial connection setup with the switch. Otherwise, you need to
manually create a known hosts file on the management station and place the host public key in
it. An entry for a public key in the known hosts file would appear similar to the following
example:
10.1.0.54 1024 35 15684995401867669259333946775054617325313674890836547254
15020245593199868544358361651999923329781766065830956 10825913212890233
76546801726272571413428762941301196195566782 59566410486957427888146206
5194174677298486546861571773939016477935594230357741309802273708779454524083971752646358058176716709
574804776117
3. Import Client's Public Key to the Switch – Use the copy tftp public-key command to copy a
file containing the public key for all the SSH client's granted management access to the switch.
(Note that these clients must be configured locally on the switch with the username command
as described on page 196.) The clients are subsequently authenticated using these keys. The
current firmware only accepts public key files based on standard UNIX format as shown in the
following example for an RSA Version 1 key:
1024 35 1341081685609893921040944920155425347631641921872958921143173880
0555361616310517759408386863110929123222682851925437460310093718772119969631781366277414168985132049
1172048303392543241016379975923714490119380060902539484084827178194372288402533115952134861022902978
982721353267131629432532818915045306393916643 steve@192.168.1.19
4. Set the Optional Parameters – Set other optional parameters, including the authentication
timeout, the number of retries, and the server key size.
5. Enable SSH Service – Use the ip ssh server command to enable the SSH server on the switch.
6. Configure Challenge-Response Authentication – When an SSH client attempts to contact the
switch, the SSH server uses the host key pair to negotiate a session key and encryption method.
Only clients that have a private key corresponding to the public keys stored on the switch can
gain access. The following exchanges take place during this process:
a. The client sends its public key to the switch.
b. The switch compares the client's public key to those stored in memory.
c. If a match is found, the switch uses the public key to encrypt a random sequence of bytes,
and sends this string to the client.
d. The client uses its private key to decrypt the bytes, and sends the decrypted bytes back to
the switch.
e. The switch compares the decrypted bytes to the original bytes it sent. If the two sets match,
this means that the client's private key corresponds to an authorized public key, and the
client is authenticated.
To use SSH with only password authentication, the host public key must still be given
to the client, either during initial connection or manually entered into the known host
file. However, you do not need to configure the client's keys.
NXA-ENET Software Management Guide
Command Line Interface
205