Understanding CHAP Authentication
What is CHAP?
Challenge Handshake Authentication Protocol (CHAP) is an optional iSCSI authentication method where the storage array (target) authenticates iSCSI initiators on the host server. Two types of CHAP are supported:
•Target CHAP
•Mutual CHAP
Target CHAP
In target CHAP, the storage array authenticates all requests for access issued by the iSCSI initiator(s) on the host server using a CHAP secret. To set up target CHAP authentication, you must enter a CHAP secret on the storage array, then configure each iSCSI initiator on the host server to send that secret each time it attempts to access the storage array.
Mutual CHAP
In addition to setting up target CHAP, you can set up mutual CHAP in which both the storage array and the iSCSI initiator authenticate each other. To set up mutual CHAP, configure the iSCSI initiator with a CHAP secret that the storage array must send to the host sever in order to establish a connection. In this
CHAP is an optional feature and is not required to use iSCSI. However, if you do not configure CHAP authentication, any host server connected to the same IP network as the storage array can read from and write to the storage array.
NOTE: When using CHAP authentication, you should configure it on both the storage array (using MDSM) and the host server (using the iSCSI initiator) before preparing virtual disks to receive data. If you prepare disks to receive data before you configure CHAP authentication, you lose visibility to the disks once CHAP
is configured.
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