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IPS Working Group                                             Mark Bakke
Internet Draft (Informational Track)                               Cisco
Expires December 2002                                         Jim Hafner
                                                            John Hufferd
                                                      Kaladhar Voruganti

                                                        Marjorie Krueger

                       iSCSI Naming and Discovery

Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026 except that the right to
   produce derivative works is not granted. Internet-Drafts are working
   documents of the Internet Engineering. Task Force (IETF), its areas,
   and its working groups. Note that other groups may also distribute
   working documents as Internet-Drafts. Internet-Drafts are draft
   documents valid for a maximum of six months and may be updated,
   replaced, or obsoleted by other documents at any time. It is
   inappropriate to use Internet- Drafts as reference material or to
   cite them other than as "work in progress." The list of current
   Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-

   The list of Internet-Draft Shadow Directories can be accessed at

Copyright Notice

   Copyright (C) The Internet Society (2002).  All Rights Reserved.


   This document provides examples of iSCSI [7] name construction and
   discussion of discovery of iSCSI resources (targets) by iSCSI
   initiators. This document complements the iSCSI protocol draft.
   Flexibility is the key guiding principle behind this document. That
   is, an effort has been made to satisfy the needs of both small
   isolated environments, as well as large environments requiring
   secure/scalable solutions.

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   Joe Czap (IBM), Howard Hall (Pirus), Jack Harwood (EMC), Yaron Klein
   (SANRAD), Larry Lamers (Adaptec), Josh Tseng (Nishan Systems)  and
   Todd Sperry (Adaptec) have participated and made contributions during
   development of this document.

Table of Contents

      1. iSCSI Names and Addresses....................................2
      2. iSCSI Alias..................................................7
      3. iSCSI Discovery.............................................11
      Appendix A: iSCSI Naming Notes.................................12
      Appendix B: Proxy Description..................................13
      Appendix C: iSCSI Names and Security Identifiers...............16
      4. References..................................................17
      5. Authors' Addresses..........................................19

1.  iSCSI Names and Addresses

   The main addressable, discoverable entity in iSCSI is an iSCSI Node.
   An iSCSI node can be either an initiator, a target, or both.  The
   rules for constructing an iSCSI name are specified in [7].

   This document provides examples of name construction that might be
   used by a naming authority.

   Both targets and initiators require names for the purpose of
   identification, and so that iSCSI storage resources can be managed
   regardless of location (address).  An iSCSI node name is also the
   SCSI device name of an iSCSI device.  The iSCSI name of a SCSI device
   is the principal object used in authentication of targets to
   initiators and initiators to targets.  This name is also used to
   identify and manage iSCSI storage resources.

   Furthermore, iSCSI names are associated with iSCSI nodes instead of
   with network adapter cards to ensure the free movement of network
   HBAs between hosts without loss of SCSI state information
   (reservations, mode page settings etc) and authorization

   iSCSI nodes also have addresses. An iSCSI address specifies a single
   path to an iSCSI node and has the following format:


   Where <domain-name> is one of:

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   - IPv4 address, in dotted decimal notation. Assumed if the name
     contains exactly four numbers, separated by dots (.), where each
     number is in the range 0..255.

   - IPv6 address, in colon-separated hexadecimal notation, as specified
     in [RFC2373] and enclosed in "[" and "]" characters, as specified
     in [RFC2732].

   - Fully Qualified Domain Name (host name). Assumed if the <domain-
     name> is neither an IPv4 nor an IPv6 address.

For iSCSI targets, the <port> in the address is optional; if specified,
it is the TCP port on which the target is listening for connections. If
the <port> is not specified, the default port 3260, assigned by IANA,
will be assumed. For iSCSI initiators, the <port> is omitted.

Examples of addresses:

The concepts of names and addresses have been carefully separated in

   - An iSCSI Name is a location-independent, permanent identifier for
     an iSCSI node.  An iSCSI node has one iSCSI name, which stays
     constant for the life of the node.  The terms "initiator name" and
     "target name" also refer to an iSCSI name.

   - An iSCSI Address specifies not only the iSCSI name of an iSCSI
     node, but also a location of that node.  The address consists of a
     host name or IP address,  a TCP port number (for the target), and
     the iSCSI Name of the  node.  An iSCSI node can have any number of
     addresses, which can change at any time, particularly if they are
     assigned via DHCP.

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A similar analogy exists for people.  A person in the USA might be:

     Robert Smith
     SSN: 333-44-5555
     Phone: +1 (763) 555.1212
     Home Address: 555 Big Road, Minneapolis, MN 55444
     Work Address: 222 Freeway Blvd, St. Paul, MN 55333

In this case, Robert's globally unique name is really his Social
Security Number.  His common name, "Robert Smith", is not guaranteed to
be unique. Robert has three locations at which he may be reached; two
Physical addresses, and a phone number.

In this example, Robert's SSN is like the iSCSI Name, his phone number
and addresses are analogous to the TCP addresses which make up an iSCSI
session, and "Robert Smith" would be a human-friendly label for this

To assist in providing a more human-readable user interface for devices
that contain iSCSI targets and initiators, a target or initiator may
also provide an alias. This alias is a simple UTF-8 string, is not
globally unique, and is never interpreted or used to identify an
initiator or device within the iSCSI protocol. Its use is described
further in section 2.

1.1.  Constructing iSCSI names using the iqn. format

   iSCSI has given the Organizational naming authority additional
   flexibility by permitting it to hand out local naming authority to
   subordinate organizations.  In this way it will be possible for the
   Organizational naming authority to assign for example, the string
   "storage", to one subgroup naming authority and "storage.tape" to
   another.  In this case the subgroups may add a ":" following their
   assigned subgroup string to ensure ongoing uniqueness. For example:
   "storage:" and "storage.tape:".  Also, additional sub-qualifiers can
   be assigned and separated by a "." as explained above.

   Using this approach, the subgroup with the sub-naming authority
   string of "storage" might, overtime, also create some Tape products.
   In this case, both subgroups might use the same qualifying names.  It
   would be expected in this case that a naming conflict might occur,
   however by using the ":" appropriately the conflicts can be avoided.
   In this example com.acme.storage:tape.sys1.xyz and
   com.acme.storage.tape:sys1.xyz would not be in conflict even though
   the same sub-names are used.

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   The following are examples of iSCSI qualified names from an equipment

                  Organization    Subgroup Naming Authority
                      Naming      and/or string Defined by
         Type  Date     Auth      Org. or Local Naming Authority
         +--++-----+ +------+ +--------------------------------+
         |  ||     | |      | |                                |



      "iqn" specifies the use of the iSCSI qualified name as the

      "2001-04" is the year and month on which the naming authority
      acquired the domain name used in this iSCSI name.

      "com.acme" defines the Organizational naming authority.  The owner
      of the DNS name "acme.com" has the sole right of use of this name
      within an iSCSI name, as well as the responsibility to keep the
      remainder of the iSCSI name unique.  In this case, acme.com
      happens to manufacture disk arrays.

      "diskarrays" was picked arbitrarily by acme.com to identify the
      disk arrays they manufacture.  Another product that ACME makes
      might use a different name, and have it's own namespace
      independent of the disk array group.

      "sn" was picked by the disk array group of ACME to show that what
      follows is a serial number.  They could have just assumed that all
      iSCSI Names are based on serial numbers, but they thought that
      perhaps later products might be better identified by something
      else.  Adding "sn" was a future-proof measure.

      "a8675309" is the serial number of the disk array, uniquely
      identifying it from all other arrays.

      "storage:" is the string that represents another sub-naming

      "storage.tape:" is still another sub-naming authority.

      "sys1.xyz" is a naming sub-qualifier.

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   The following is an example of a name that might be constructed by an
   research organization:

                      Organization               String
                        Naming                  Defined by Org.
        Type  Date     Authority               Naming Authority
         +-+ +-----+ +----------------------+ +-----------+
         | | |     | |                      | |           |

   In the above example, Professor Oaks of Pika University is building
   research prototypes of iSCSI targets.  Pika-U's computer science
   department allows each user to use his or her user name as a naming
   authority for this type of work.  Professor Oaks chose to use
   "proto.target4" for a particular target.

   The following is an example of an iSCSI name string from a storage
   service provider:

                     Organization       String
                        Naming       Defined by Org.
        Type  Date    Authority     Naming Authority
         +-+ +-----+ +--------+ +----------------------+
         | | |     | |        | |                      |

   In this case, a storage service provider (my-ssp.com) has decided to
   re-name the targets from the manufacturer, to provide the flexibility
   to move the customer's data to a different storage subsystem should
   the need arise.

   My-ssp has configured the iSCSI Name on this particular target for
   one of its customers, and has determined that it made the most sense
   to track these targets by their Customer ID number and a disk number.
   This target was created for use by customer #4567, and is the 107th
   target configured for this customer.

   Note that when reversing these domain names, the first
   component(after the "iqn.") will always be a top-level domain name,
   which includes "com", "edu", "gov", "org", "net", "mil", or one of
   the two-letter country codes.  The use of anything else as the first
   component of these names is not allowed.  In particular, companies
   generating these names must not eliminate their "com." from the

   Again, these iSCSI names are NOT addresses.  Even though they make
   use of DNS domain names, they are used only to specify the naming
   authority.  An iSCSI name contains no implications of the iSCSI

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   target or initiator's location.  The use of the domain name is only a
   method of re-using an already ubiquitous name space.

1.2.  Constructing iSCSI names using the eui. format

   The iSCSI eui. naming format allows a naming authority to use IEEE
   EUI-64 identifiers in constructing iSCSI names.  The details of
   constructing EUI-64 identifiers are specified by the IEEE
   Registration Authority (see [11]).

   Example iSCSI name :

        Type  EUI-64 identifier (ASCII-encoded hexidecimal)
        |  ||              |

2.  iSCSI Alias

   The iSCSI alias is a UTF-8 text string that may be used as an
   additional descriptive name for an initiator and target.  This may
   not be used to identify a target or initiator during login, and does
   not have to follow the uniqueness or other requirements of the iSCSI
   name.  The alias strings are communicated between the initiator and
   target at login, and can be displayed by a user interface on either
   end, helping the user tell at a glance whether the initiators and/or
   targets at the other end appear to be correct.  The alias must NOT be
   used to identify, address, or authenticate initiators and targets.

   The alias is a variable length string, between 0 and 255 characters,
   and is terminated with at least one NULL (0x00) character.  No other
   structure is imposed upon this string.

2.1.  Purpose of an Alias

   Initiators and targets are uniquely identified by an iSCSI Name.
   These identifiers may be assigned by a hardware or software
   manufacturer, a service provider, or even the customer.  Although
   these identifiers are nominally human- readable, they are likely be
   be assigned from a point of view different from that of the other
   side of the connection.  For instance, a target name for a disk array
   may be built from the array's serial number, and some sort of
   internal target ID.  Although this would still be human-readable and
   transcribable, it offers little assurance to someone at a user
   interface who would like to see "at-a-glance" whether this target is

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   really the correct one.

   The use of an alias helps solve that problem.  An alias is simply a
   descriptive name that can be assigned to an initiator target, that is
   independent of the name, and does not have to be unique.  Since it is
   not unique, the alias must be used in a purely informational way.  It
   may not be used to specify a target at login, or used during

   Both targets and initiators may have aliases.

2.2.  Target Alias

   To show the utility of an alias, here is an example using an alias
   for an iSCSI target.

   Imagine sitting at a desktop station that is using some iSCSI devices
   over a network.  The user requires another iSCSI disk, and calls the
   storage services person (internal or external), giving any
   authentication information that the storage device will require for
   the host.  The services person allocates a new target for the host,
   and sends the Target Name for the new target, and probably an
   address, back to the user.  The user then adds this Target Name to
   the configuration file on the host, and discovers the new device.

   Without an alias, a user managing an iSCSI host would click on some
   sort of management "show targets" button to show the targets to which
   the host is currently connected.

   |  Target Name
   |  iqn.1995-04.com.acme:sn.5551212.target.450
   |  iqn.1995-04.com.acme:sn.5551212.target.489
   |  iqn.1995-04.com.acme:sn.8675309
   |  iqn.2001-04.com.acme.storage:tape.sys1.xyz
   |  iqn.2001-04.com.acme.storage.tape:sys1.xyz

   In the above example, the user sees a collection of iSCSI Names, but
   with no real description of what they are for.  They will, of course,
   map to a system-dependent device file or drive letter, but it's not
   easy looking at numbers quickly to see if everything is there.

   If a more intelligent target configures an alias for each target,

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   perhaps at the time the target was allocated to the host, a more
   descriptive name can be given.  This alias may be sent back to the
   initiator as part of the login response, or found in the iSCSI MIB.
   It then might be used in a display such as this.  The new display
   might look like:

   |  Alias          Target Name
   |  Oracle 1       iqn.1995-04.com.acme:sn.5551212.target.450
   |  Local Disk     iqn.1995-04.com.acme:sn.5551212.target.489
   |  Exchange 2     iqn.1995-04.com.acme:sn.8675309

   This would give the user a better idea of what's really there.

   In general, flexible, configured aliases will probably be supported
   by larger storage subsystems and configurable gateways.  Simpler
   devices will likely not keep configuration data around for things
   such as an alias.  The TargetAlias string could be either left
   unsupported (not given to the initiator during login) or could be
   returned as whatever the "next best thing" that the target has that
   might better describe it.  Since it does not have to be unique, it
   could even return SCSI inquiry string data.

   Note that if a simple initiator does not wish to keep or display
   alias information, it can be simply ignored if seen in the login

2.3.  Initiator Alias

   An initiator alias can be used in the same manner as a target alias.
   An initiator may send the alias in a login request, when it sends its
   iSCSI Initiator Name.  The alias is not used for authentication, but
   may be kept with the session information for display through a
   management GUI or command-line interface (for a more complex
   subsystem or gateway), or through the iSCSI MIB.

   Note that a simple target can just ignore the Initiator Alias if it
   has no management interface on which to display it.

   Usually just the hostname would be sufficient for an initiator alias,
   but a custom alias could be configured for the sake of the service
   provider if needed.  Even better would be a description of what the
   machine was used for, such as "Exchange Server 1", or "User Web

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   Here's an example of a management interface showing a list of
   sessions on an iSCSI target  network entity.  For this display, the
   targets are using an internal target number, which is a fictional
   field that has purely internal significance.

   |  Target   Initiator Name
   |  450      iqn.1995-04.com.sw:cd.12345678-OEM-456
   |  451      iqn.1995-04.com.os:hostid.A598B45C
   |  309      iqn.1995-04.com.sw:cd.87654321-OEM-259

   And with the initiator alias displayed:

   |  Target Alias               Initiator Name
   |  450    Web Server 4        iqn.1995-04.com.sw:cd.12345678-OEM-456
   |  451    scsigate.yours.com  iqn.1995-04.com.os:hostid.A598B45C
   |  309    Exchange Server     iqn.1995-04.com.sw:cd.87654321-OEM-259

   This gives the storage administrator a better idea of who is
   connected to their targets.  Of course, one could always do a reverse
   DNS lookup of the incoming IP address to determine a host name, but
   simpler devices really don't do well with that particular feature due
   to blocking problems, and it won't always work if there is a firewall
   or iSCSI gateway involved.

   Again, these are purely informational and optional and require a
   management application.

   Aliases are extremely easy to implement.  Targets just send a
   TargetAlias whenever they send a TargetName.  Initiators just send an
   InitiatorAlias whenever they send an InitiatorName.  If an alias is
   received that does not fit, or seems invalid in any way, it is

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3.  iSCSI Discovery

   The goal of iSCSI discovery is to allow an initiator to find the
   targets to which it has access, and at least one address at which
   each target may be accessed. This should generally be done using as
   little configuration as possible.  This section defines the discovery
   mechanism only; no attempt is made to specify central management of
   iSCSI devices within this document.  Moreover, iSCSI discovery
   mechanism only deals with target discovery and one still needs to use
   the SCSI protocol for LUN discovery.

   In order for an iSCSI initiator to establish an iSCSI session with an
   iSCSI  target, the initiator needs the IP address, TCP port number
   and iSCSI  target name information. The goal of iSCSI discovery
   mechanism is to provide low overhead support for small iSCSI setups,
   and scalable discovery solutions for large enterprise setups. Thus,
   there are several methods that may be used to find targets ranging
   from configuring a list of targets and addresses  on each initiator
   and doing no discovery at all, to configuring nothing on each
   initiator, and allowing the initiator to discover  targets
   dynamically. The various discovery mechanisms differ in their
   assumptions about what information is already available to the
   initiators and what information needs to be still discovered.

   iSCSI supports the following discovery mechanisms:

   a. Static Configuration: This mechanism assumes that the IP address,
      TCP port and the iSCSI target name information are already
      available to the initiator. The initiators need to perform no
      discovery in this approach. The initiator uses the IP address and
      the TCP port information to establish a TCP connection, and it
      uses the iSCSI target name information to establish an iSCSI
      session. This discovery option is convenient for small iSCSI

   b. SendTargets: This mechanism assumes that the IP address and TCP
      port information are already available to the initiator. The
      initiator then uses this information to establish a discovery
      session to the Network Entity.  The initiator then subsequently
      issues the SendTargets text command to query information about the
      iSCSI targets available at the particular Network Entity (IP
      address).  SendTargets command details can be found in the iSCSI
      draft [7].  This discovery option is convenient for iSCSI gateways
      and routers.

   c. Zero-Configuration: This mechanism assumes that the initiator does
      not have any information about the target. In this option, the
      initiator can either multicast discovery messages directly to the

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      targets or it can send discovery messages to storage name servers.
      Currently, there are many general purpose discovery frameworks
      available such as Salutation[2], Jini[2],UPnP[2], SLP[17] and
      iSNS[8].  However, with respect to iSCSI, SLP can clearly perform
      the needed discovery functions [21], while iSNS [8] can be used to
      provide related management functions including notification,
      access management, configuration, and discovery management.  iSCSI
      equipment that need discovery functions beyond SendTargets should
      at least implement SLP, and then consider iSNS when extended
      discovery management capabilities are required such as in larger
      storage networks.  It should be noted that since iSNS will support
      SLP, iSNS can be used to help manage the discovery information
      returned by SLP.

Appendix A: iSCSI Name Notes

   Some iSCSI Name Examples for Targets

       - Assign to a target based on controller serial number


       - Assign to a target based on serial number


   Where oracle_database_1 might be a target label assigned by a user.

   This would be useful for a controller that can present different
   logical targets to different hosts.

   Obviously, any naming authority may come up with its own scheme and
   hierarchy for these names, and be just as valid.

   A target iSCSI Name should never be assigned based on interface
   hardware, or other hardware that can be swapped and moved to other

   Some iSCSI Name Examples for Initiators

       - Assign to the OS image by fully qualified host name


   Note the use of two FQDNs - that of the naming authority and also
   that of the host that is being named.  This can cause problems, due
   to limitations imposed on the size of the iSCSI Name.

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       - Assign to the OS image by OS install serial number


   Note that this breaks if an install CD is used more than once.
   Depending on the O/S vendor's philosophy, this might be a feature.

       - Assign to the Raid Array by a service provider


Appendix B: iSCSI Proxies and Firewalls Taxonomy

   iSCSI has been designed to allow SCSI initiators and targets to
   communicate over an arbitrary network.  This, making some assumptions
   about authentication and security, means that in theory, the whole
   internet could be used as one giant storage network.

   However, there are many access and scaling problems that would come
   up when this is attempted.

   1. Most iSCSI targets may only meant to be accessed by one or a few
   initiators.  Discovering everything would be unnecessary.

   2. The initiator and target may be owned by separate entities, each
   with their own directory services, authentication, and other schemes.
   An iSCSI-aware proxy may be required to map between these things.

   3. Many environments use non-routable IP addresses, such as the "10."

   For these and other reasons, various types of firewalls and proxies
   will be deployed for iSCSI, similar in nature to those already
   handling protocols such as HTTP and FTP.

B.1. Port Redirector

   A port redirector is a stateless device that is not aware of iSCSI.
   It is used to do Network Address Translation (NAT), which can map IP
   addresses between routable and non-routable domains, as well as map
   TCP ports.  While devices providing these capabilities can often
   filter based on IP addresses and TCP ports, they generally do not
   provide meaningful security, and are used instead to resolve internal
   network routing issues.

   Since it is entirely possible that these devices are used as routers
   and/or aggregators between a firewall and an iSCSI initiator or
   target, iSCSI connections must be operable through them.

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   Effects on iSCSI:

   - iSCSI-level data integrity checks must not include information from
     the TCP or IP headers, as these may be changed in between the
     initiator and target.

   - iSCSI messages that specify a particular initiator or target, such
     as login requests and third party requests, should specify the
     initiator or target in a location-independent manner.  This is
     accomplished using the iSCSI Name.

B.2. SOCKS server

   A SOCKS server can be used to map TCP connections from one network
   domain to another.  It is aware of the state of each TCP connection.

   The SOCKS server provides authenticated firewall traversal for
   applications that are not firewall-aware.  Conceptually, SOCKS is a
   "shim-layer" that exists between the application (i.e., iSCSI) and

   To use SOCKS, the iSCSI initiator must be modified to use the
   encapsulation routines in the SOCKS library.  The initiator the opens
   up a TCP connection to the SOCKS server, typically on the canonical
   SOCKS port 1080.  A sub-negotiation then occurs, during which the
   initiator is either authenticated or denied the connection request.
   If authenticated, the SOCKS server then opens a TCP connection to the
   iSCSI target using addressing information sent to it by the initiator
   in the SOCKS shim.  The SOCKS server then forwards iSCSI commands,
   data, and responses between the iSCSI initiator and target.

   Use of the SOCKS server requires special modifications to the iSCSI
   initiator.  No modifications are required to the iSCSI target.

   As a SOCKS server can map most of the addresses and information
   contained within the IP and TCP headers, including sequence numbers,
   its effects on iSCSI are identical to those in the port redirector.

B.3. SCSI gateway

   This gateway presents logical targets (iSCSI Names) to the
   initiators, and maps them to real iSCSI targets as it chooses.  The
   initiator sees this gateway as a real iSCSI target, and is unaware of
   any proxy or gateway behavior.  The gateway may manufacture its own
   iSCSI Names, or use those provided by the real devices.  This type of
   gateway is used to represent parallel SCSI, Fibre Channel, SSA, or
   other devices as iSCSI devices.

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   Effects on iSCSI:

   - Since the initiator is unaware of any addresses beyond the gateway,
     the gateway's own address is for all practical purposes the real
     address of a target.  Only the iSCSI Name needs to be passed.  This
     is already done in iSCSI, so there are no further requirements to
     support SCSI gateways.

B.4. iSCSI Proxy

   An iSCSI proxy is a SCSI gateway that happens to be terminating the
   iSCSI protocol on both sides, rather than translate between iSCSI and
   some other transport.  Since an iSCSI initiator's discovery or
   configuration of a set of targets makes use of address-independent
   iSCSI names, iSCSI does not have the same proxy addressing problems
   as HTTP, which includes address information into its URLs.  If a
   proxy is to provide services to an initiator on behalf of a target,
   the proxy allows the initiator to discover its address for the
   target, and the actual target device is discovered only by the proxy.
   Neither the initiator nor the iSCSI protocol needs to be aware of the
   existence of the proxy.

   Effects on iSCSI:

   - Same as a SCSI gateway.  The only other effect is that iSCSI must
     separate data integrity checking on iSCSI headers and iSCSI data,
     to allow the data integrity check on the data to be propagated end-
     to-end through the proxy.

B.5. Stateful Inspection Firewall (stealth iSCSI firewall)

   The stealth model would exist as an iSCSI-aware firewall, that is
   invisible to the initiator, but provides capabilities found in the
   iSCSI proxy.

   Effects on iSCSI:

   - Since this is invisible, there are no additional requirements on
     the iSCSI protocol for this one.

   This one is more difficult in some ways to implement, simply because
   it has to be part of a standard firewall product, rather than part of
   an iSCSI-type product.

   Also note that this type of firewall is only effective in the
   outbound direction (allowing an initiator behind the firewall to
   connect to an outside target), unless the iSCSI target is located in
   a DMZ.  It does not provide adequate security otherwise.

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Appendix C: iSCSI Names and Security Identifiers

   This document has described the creation and use of iSCSI Node Names.
   There will be trusted environments where this is a sufficient form of
   identification. In these environments the iSCSI Target may have an
   Access Control List (ACL), which will contain a list of authorized
   entities that are permitted to access a restricted resource (in this
   case a Target Storage Controller).  The iSCSI Target will then use
   that ACL to permit (or not) certain iSCSI Initiators to access the
   storage at the iSCSI Target Node. This form of ACL is used to prevent
   trusted initiators from making a mistake and connecting to the wrong
   storage controller.

   It is also possible that the ACL and the iSCSI Initiator Node Name
   can be used in conjunction with the SCSI layer for the appropriate
   SCSI association of LUNs with the Initiator.  The SCSI layer's use of
   the ACL will not be discussed further in this document.

   There will be situations where the iSCSI Nodes exist in untrusted
   environments. That is, some iSCSI Initiator Nodes may be authorized
   to access an iSCSI Target Node, however, because of the untrusted
   environment, nodes on the network cannot be trusted to give the
   correct iSCSI Initiator Node Names.

   In untrusted environments an additional type of identification is
   required to assure the target that it really knows the identity of
   the requesting entity.

   The authentication and authorization in the iSCSI layer is
   independent of anything that IPSec might handle, underneath or around
   the TCP layer. This means that the initiator node needs to pass some
   type of security related identification information (e.g. userid) to
   a security authentication process such as SRP, CHAP, Kerberos etc.
   (These authentication processes will not be discussed in this

   Upon the completion of the iSCSI security authentication, the
   installation knows "who" sent the request for access.  The
   installation must then check to ensure that such a request, from the
   identified entity, is permitted/authorized.  This form of
   Authorization is generally accomplished via an Access Control List
   (ACL) as described above.  Using this authorization process, the
   iSCSI target will know that the entity is authorized to access the
   iSCSI Target Node.

   It may be possible for an installation to set a rule that the
   security identification information (e.g. UserID) be equal to the
   iSCSI Initiator Node Name. In that case, the ACL approach described

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   above should be all the authorization that is needed.

   If, however, the iSCSI Initiator Node Name is not used as the
   security identifier there is a need for more elaborate ACL
   functionality. This means that the target requires a mechanism to map
   the security identifier (e.g. UserID) information to the iSCSI
   Initiator Node Name.  That is, the target must be sure that the
   entity requesting access is authorized to use the name, which was
   specified with the Login Keyword "InitiatorName=".  For example, if
   security identifier 'Frank' is authorized to access the target via
   iSCSI InitiatorName=xxxx, but 'Frank' tries to access the target via
   iSCSI InitiatorName=yyyy, then this login should be rejected.

   On the other hand, it is possible that 'Frank' is a roaming user (or
   a Storage Administrator) that "owns" several different systems, and
   thus, could be authorized to access the target via multiple different
   iSCSI initiators. In this case, the ACL needs to have the names of
   all the initiators through which 'Frank' can access the target.

   There may be other more elaborate ACL approaches, which can also be
   deployed to provide the installation/user with even more security
   with flexibility.

   The above discussion is trying to inform the reader that, not only is
   there a need for access control dealing with iSCSI Initiator Node
   Names, but in certain iSCSI environments there might also be a need
   for other complementary security identifiers.

4.  References

[1]   Pascoe, R., "Building Networks on the Fly", in IEEE
      Spectrum,March, 2002.

[2]   John, R., "UPnP, Jini and Salutation- A look at some popular
      coordination frameworks for future networked devices",
      http://www.cswl.com/whiteppr/tech/upnp.html", June 17, 1999.

[3]   http://www.srvloc.org

[4]   Freed, N., "Behavior of and Requirements for Internet Firewalls",
      RFC 2979, October 2000.

[5]   ANSI/IEEE Std 802-1990, Name: IEEE Standards for Local and
      Metropolitan Area Networks: Overview and Architecture

[6]   Kessler, G. and Shepard, S., "A Primer On Internet and TCP/IP
      Tools and Utilities", RFC 2151, June 1997.

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[7]   Satran, J., et al, "iSCSI", draft-ietf-ips-iscsi-13.txt, June,

[8]   Tseng, J. et al, "Internet Storage Name Service (iSNS)", draft-
      ietf-ips-isns-10.txt, May 2002.

[9]   RFC 1737, "Functional Requirements for Uniform Resource Names".

[10]  RFC 1035, "Domain Names - Implementation and Specification".  OUI
      - "IEEE OUI and Company_Id Assignments",

[11]  EUI - "Guidelines for 64-bit Global Identifier (EUI-64)
      Registration Authority

[12]  RFC 2396, "Uniform Resource Identifiers".

[13]  RFC 2276, "Architectural Principles of URN Resolution".

[14]  RFC 2483, "URI Resolution Services".

[15]  RFC 2141, "URN Syntax".

[16]  RFC 2611, "URN Namespace Definition Mechanisms".

[17]  RFC 2608, SLP Version 2.

[18]  RFC 2610, DHCP Options for the Service Location Protocol.

[19]  P. Sarkar et al, "A Standard for Bootstrapping Clients using the
      iSCSI Protocol", draft-ietf-ips-iscsi-boot-05, February, 2002.

[21]  M. Bakke et al,"Finding iSCSI Targets and Name Servers using SLP",
      draft-ietf-ips-iscsi-slp-03, March, 2002.

[22]  Sun Microsystems, "Java Language Specification", section 7.7
      "Unique Package Names", 2000,

[23]  Flanagan, et. al, "Java in a Nutshell", O'Reilly, 1997.

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5.  Authors' Addresses

   Address comments to:

   Kaladhar Voruganti
   IBM Almaden Research Center
   650 Harry Road
   San Jose, CA 95120
   Email: kaladhar@us.ibm.com

   Mark Bakke
   Cisco Systems, Inc.
   6450 Wedgwood Road
   Maple Grove, MN 55311
   Phone: +1 763 398-1054
   Email: mbakke@cisco.com

   Jim Hafner
   IBM Almaden Research Center
   650 Harry Road
   San Jose, CA 95120
   Phone: +1 408-927-1892
   Email: hafner@almaden.ibm.com

   Marjorie Krueger
   Hewlett-Packard Corporation
   8000 Foothills Blvd
   Roseville, CA 95747-5668, USA
   Phone: +1 916 785-2656
   Email: marjorie_krueger@hp.com

6.  Full Copyright Statement

   Copyright (C) The Internet Society (2002). All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others,  and derivative works that comment on or otherwise explain it
   or assist  in its implementation may be prepared, copied, published
   and distributed,in whole or in part, without restriction of any kind,
   provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works. However, this
   document itself may not be modified in any way, Full Copyright
   Statement such as by removing the copyright notice or references to
   the Internet Society or other Internet organizations, except as
   needed for the purpose of developing Internet standards in which case
   the procedures for copyrights defined in the Internet Standards
   process must be followed, or as required to translate it into
   languages other than English.

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   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an


   Funding for the RFC Editor function is currently provided by the
   Internet Society.

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