HP-UX iSCSI Software Initiator Support Guide, HP-UX 11i v1 and 11i v2, July 2005

Chapter 5
Management
iSCSI Software Initiator Daemons
60
iSCSI Software Initiator Daemons
iSCSI Software Initiator Name Resolution Daemon (iscsi_resolvd)
iscsi_resolvd is a user level daemon responsible for resolving a hostname to an IP address. This daemon
operates by receiving hostnames from the iSCSI Software Initiator and returning the corresponding IP
addresses to the iSCSI Software Initiator. This daemon is automatically started from the iSCSI Software
Initiator start-up script during HP-UX system start-up.
iSCSI Challenge-Handshake Authentication Protocol Daemon (iradd)
CHAP authentication for iSCSI uses the iradd daemon. The iradd daemon allows the iSCSI Software
Transport driver to communicate with a RADIUS server.
The iradd daemon helps the initiator authenticate targets. It is not used for Uni-directional CHAP
authentication, where the initiator is authenticated by the target.
The iradd daemon receives authentication requests from the iSCSI Software Transport driver. It forwards
the authentication requests to the RADIUS server via a RADIUS message "Access Request". The RADIUS
server responds to iradd with a RADIUS message, "Access Accept" (if the authentication of the target
succeeded), or with "Access Reject" (if the authentication failed). The iradd daemon then passes the result to
the iSCSI Software Transport driver.
The iradd daemon has the following command line, which is executed in the iSCSI Software Initiator
startup script, once CHAP has been requested through iscsiutil:
# /opt/iscsi/bin/iradd [-r <retries>] [-t <timeout>] [-i <id>]
where:
-r retries is the number of retries iradd will perform until a reply is received from the RADIUS server.
The unreliable UDP protocol is used between iradd and the RADIUS server. The default value is 10.
-t timeout is the timeout in seconds between retry attempts. The default value is 3.
-i id is the starting message identifier (number) used in the RADIUS messages between iradd and the
RADIUS server. The default value is the process id of iradd.
NOTE For more information on CHAP see “Challenge-Handshake Authentication Protocol (CHAP)
Configuration” on page 43.
iSCSI Service Location Protocol Daemon (islpd)
The islpd daemon is a user space daemon that implements the Service Location Protocol (SLP) User Agent
(UA) and the interface to the iSCSI transport driver. The iSCSI transport driver adds discovered iSCSI
targets to the persistent information maintained in the kernel registry. Dynamic scanning based on SLP is
triggered when the ioscan command is executed. The UA queries the DA to obtain a list of all available iSCSI
targets on the network that are known to the DA. Each target address discovered is registered in the kernel
registry on the host by the iSCSI transport driver. For more information on SLP see “Service Location
Protocol Based Dynamic Discovery” on page 26.