Kerberos Operation; Authenticating To A Boundary Switch; Obtaining A Tgt From A Kdc - Cisco WS-CBS3032-DEL Software Configuration Manual

Chapter 6 Configuring Switch-Based Authentication

Kerberos Operation

A Kerberos server can be a switch that is configured as a network security server and that can
authenticate remote users by using the Kerberos protocol. Although you can customize Kerberos in a
number of ways, remote users attempting to access network services must pass through three layers of
security before they can access network services.
To authenticate to network services by using a switch as a Kerberos server, remote users must follow
these steps:
1.
2.
3.

Authenticating to a Boundary Switch

This section describes the first layer of security through which a remote user must pass. The user must
first authenticate to the boundary switch. This process then occurs:
1.
2.
3.
4.
5.
A remote user who initiates a un-Kerberized Telnet session and authenticates to a boundary switch is
inside the firewall, but the user must still authenticate directly to the KDC before getting access to the
network services. The user must authenticate to the KDC because the TGT that the KDC issues is stored
on the switch and cannot be used for additional authentication until the user logs on to the switch.

Obtaining a TGT from a KDC

This section describes the second layer of security through which a remote user must pass. The user must
now authenticate to a KDC and obtain a TGT from the KDC to access network services.
For instructions about how to authenticate to a KDC, see the "Obtaining a TGT from a KDC" section in
the "Security Server Protocols" chapter of the Cisco IOS Security Configuration Guide, Release 12.2.
OL-13270-06
Authenticating to a Boundary Switch, page 6-43
Obtaining a TGT from a KDC, page 6-43
Authenticating to Network Services, page 6-44
The user opens an un-Kerberized Telnet connection to the boundary switch.
The switch prompts the user for a username and password.
The switch requests a TGT from the KDC for this user.
The KDC sends an encrypted TGT that includes the user identity to the switch.
The switch attempts to decrypt the TGT by using the password that the user entered.
If the decryption is successful, the user is authenticated to the switch.
–
– If the decryption is not successful, the user repeats Step 2 either by re-entering the username
and password (noting if Caps Lock or Num Lock is on or off) or by entering a different username
and password.
Cisco Catalyst Blade Switch 3130 and 3032 for Dell Software Configuration Guide
Controlling Switch Access with Kerberos
6-43