Title: OpenBSD and iSCSI part1: the target (server)

	Title: OpenBSD and iSCSI part1: the target (server)
	Author: Solène
	Date: 21 February 2019
	Tags: unix openbsd iscsi
	Description:

	This is the first article of a series about iSCSI.

	iSCSI is a protocol designed for sharing a block device across
	network as if it was a local disk. This doesn't permit using that
	disk from multiples places at once though, except if you use a
	specific filesystem like GFS2 or OCFS2 (Linux only). In this article,
	we will learn how to create an iSCSI target, which is the "server"
	part of iSCSI, the target is the system holding the disk and making
	it available to others on the network.

	OpenBSD does not have an target server in base, we will have to use
	net/netbsd-iscsi-target for this. The setup is really simple.

	First, we obviously need to install the package and we will activate
	the daemon
	so it start automatically at boot, but don't start it yet:

	# pkg_add netbsd-iscsi-target
	# rcctl enable iscsi_target

	The configurations files are in /etc/iscsi/ folder, it contains
	files
	auths and targets. The default configuration files are the
	same. By
	looking at the source code, it seems that auths is used there but
	it seems
	to have no use at all. We will just overwrite it everytime we modify
	targets to keep them in sync.

	Default /etc/iscsi/targets (with comments stripped):

	extent0 /tmp/iscsi-target0 0 100MB
	target0 rw extent0 10.4.0.0/16

	The first line defines the file holding our disk in the second field,
	and the
	last field defines the size of it. When iscsi-target will be started,
	it will
	create files as required with the size defined here.

	The second line defines permissions, in that case, the extent0 disk can
	be used
	read/write by the net 10.4.0.0/16. For this example, I will only change
	the
	netmask to suit my network, then I copy targets over auths.

	Let's start the daemon:

	# rcctl start iscsi_target
	# rcctl check iscsi_target
	iscsi_target(ok)

	If you want to restrict ports using PF, you only have to allows the TCP
	port
	3260 from the network that will connect to the target. The according
	line would
	looks like this:

	pass in proto tcp to port 3260

	Done!