Brocade 6910 Ethernet Access Switch Configuration Guide (Supporting R2.2.0.0) - Manual (Page 932)

876 Brocade 6910 Ethernet Access Switch Configuration Guide
53-1002651-02
42
Configuring Secure Shell
3. Import Client’s Public Key to the Switch – See “Importing User Public Keys” on page 880, or
use the copy tftp public-key command (see “copy” on page 67) 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 via the User Accounts page as described under
“Configuring User Accounts” on page 860.) 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
13410816856098939210409449201554253476316419218729589211431738800555361616310
51775940838686311092912322268285192543746031009371877211996963178136627741416
8985132049117204830339254324101637997592371449011938006090253948408482717819
4372288402533115952134861022902978982721353267131629432532818915045306393916
643 [email protected]
4. Set the Optional Parameters – On the SSH Settings page, configure the optional parameters,
including the authentication timeout, the number of retries, and the server key size.
5. Enable SSH Service – On the SSH Settings page, enable the SSH server on the switch.
6. Authentication – One of the following authentication methods is employed:
Password Authentication (for SSH v1.5 or V2 Clients)
a. The client sends its password to the server.
b. The switch compares the client's password to those stored in memory.
c. If a match is found, the connection is allowed.
NOTE
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.
Public Key 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 access it. The following
exchanges take place during this process:
Authenticating SSH v1.5 Clients
a. The client sends its RSA 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 its secret key to generate a random 256-bit string as a
challenge, encrypts this string with the user’s public key, and sends it to the client.
d. The client uses its private key to decrypt the challenge string, computes the MD5
checksum, and sends the checksum back to the switch.
e. The switch compares the checksum sent from the client against that computed for the
original string it sent. If the two checksums match, this means that the client's private key
corresponds to an authorized public key, and the client is authenticated.
Authenticating SSH v2 Clients
a. The client first queries the switch to determine if DSA public key authentication using a
preferred algorithm is acceptable.