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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.) 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
055536161631051775940838686311092912322268285192543746031009371877211996
963178136627741416898513204911720483033925432410163799759237144901193800
609025394840848271781943722884025331159521348610229029789827213532671316
29432532818915045306393916643 steve@192.168.1.19
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 Industrial Managed Switch compares the client's password to those stored in memory.
c.
If a match is found, the connection is allowed.
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.
7.
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.
276
User's Manual of IGSW-2840
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