At some point you will be asked by a Storage Engineer for your system’s iSCSI Initiator Node Name or your iqn. This list shows you how to get your local iSCSI initiator name or iqn from the command line. This assumes the iSCSI service is installed, enabled and running. If you have a different way or want to add an OS or platform to this list simply leave a comment and I’ll add it.

> smitty iscsi
select > iSCSI Protocol Device
select > Change / Show Characteristics of an iSCSI Protocol Device

FreeBSD (v10 and newer. Thanks to Edward Tomasz Napierala for this update):
> iscsictl -v  (only after you have established a session with your array)

> iscsiutil -l

> cat /etc/iscsi/initiatorname.iscsi

NetApp Data ONTAP: (this is a target iqn not a host iqn)
> iscsi nodename

Cluster Mode from the clustershell:
> vserver iscsi show

NetBSD: (please make this easier NetBSD developers! How about an iscsictl list_initiators command?)
> iscsictl add_send_target -a <hostname or IP of your target/storage)
Added Send Target 1
> iscsictl refresh_targets
> iscsictl list_targets
1: iqn.1992-08.com.netapp:sn.84167939
> iscsictl login -P 2
Created Session 2, Connection 1
> iscsictl list_sessions
Session 2: Target iqn.1992-08.com.netapp:sn.84167939

On the NetApp filer find the initiator:
netapp01> iscsi initiator show
Initiators connected:
TSIH  TPGroup  Initiator/ISID/IGroup
4    1000   nbsd611.lab.slice2.com (iqn.1994-04.org.netbsd:iscsi.nbsd611.lab.slice2.com:0 / 40:00:01:37:00:00 / )

Solaris 11:
> iscsiadm list initiator-node

VMware ESXi 5.1:
ESXi console:
Get the devices first:
> esxcfg-scsidevs -a | grep iSCSI
Then get the iqn (in this case vmhba33 is the iSCSI device)
> vmkiscsi-tool -I -l vmhba33

> esxcli -s <esxihostname or ip> -u root iscsi adapter get -A vmhba33