Frank Swarbrick wrote:
>"more than 8"?  What's the limit, if any?

The z/OS LDAP Server's CN limit is 256 characters, so it's at least that 
large.

>Which system components/products permit/prohibit this?
>(Start your list with JCL.)

You can specify pretty much anything you want in JCL. Do you mean JES2? If 
so, that'll use maximum 8 character user IDs.

Whatever list I come up with is necessarily going to be partial, but as 
we've already seen (I linked to the documentation) MQ for z/OS can 
authenticate users with the IBM Directory Server for z/OS at least in 
certain contexts. CICS Transaction Server for z/OS also can in certain 
contexts. See for example this documentation:

https://www.ibm.com/support/knowledgecenter/SSGMCP_5.5.0/security/java/dist_identity.html

Other z/OS components and products that come to mind include the z/OS 
Container Extensions, WebSphere Application Server for z/OS, and the IBM 
HTTP Server for z/OS. See for example here:

https://www.ibm.com/support/knowledgecenter/SSEQTJ_9.0.5/com.ibm.websphere.ihs.doc/ihs/tihs_apacheldapcfg.html

There are quite a large number of intersections, so many that we've now 
reached the stage when one of them fell overboard. z/OS HCD had some LDAP 
affinities (would you believe), but they were removed in z/OS 2.3. 
Evidently that one was too "crazy." :-)

Bob Bridges wrote:
>I'm about to expose my ignorance here: IDS and LDAP, aren't they just
>IBM's attempt to let z/OS talk to non-z/OS systems?

No, not according to IBM. Right at the very beginning of the IBM (Tivoli) 
Directory Server for z/OS redbook, Section 1.1, it says that this 
component is for both z/OS and non-z/OS workloads. So take the hint: if 
maximum 8 character user IDs are constraining, then start using the IBM 
Directory Server for z/OS to authenticate users if you aren't already, 
as/where it makes sense for you. Or use a certain something else to 
authenticate (see below).

>Or put it this way: If you say I can be authenticated via LPAR using a
>longer ID, and then perform tasks on the mainframe using that ID, how 
does
>RACF-or-whatever determine permissions?

First of all, you didn't include "RACF" in the text I reacted to. RACF is 
a popular but optional z/OS component. z/OS is not equivalent to RACF. 
Second, if you are talking about RACF specifically, yes, it does use 
maximum 8 character user IDs.... But you're not required to authenticate 
with them. I (somewhat facetiously) pointed out that you don't have to 
authenticate at all, although (as I also pointed out) I'll urge you to at 
least perform authorizations. More seriously, z/OS RACF has supported 
client certificate authentication since the 1990s. (This feature was 
initially introduced way back in the OS/390 days. The OS/390 TN3270E 
Server picked up support for it with OS/390 2.9, backported to 2.8. IBM 
Personal Communications picked up support for this feature in the late 
1990s, too.) See here for an introductory reference:

https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.icha700/icha700_Enabling_client_login_using_certificates.htm

In this case users don't present maximum 8 character user IDs at all, or 
not really. They present digital certificates, and those may be coming 
from PIN-protected smart cards for example. Please do check this out! It's 
a really nifty solution, and the world seems to be (re)discovering it 
lately.

Another approach you can take is to authenticate with the IBM Directory 
Server for z/OS (or other LDAP server, but that one is a terrific one) and 
leverage a mapping to a "short name." This is the approach z/VSE takes 
when you turn on its included LDAP authentication support, and it's both 
simple and clever. You're certainly free to submit RFEs for IBM's 
consideration if you'd like more such features, such as a TSO/E sign on 
screen comparable to z/VSE's LDAP friendly sign on screen.

>...Even if I've logged on from some other OS using a longer ID,
>inside z/OS the system is still using an 8-byte ID.

But "who cares?" Users presenting longer IDs or client certificates 
certainly don't. "If a tree falls in the woods...." As long as there is at 
least adequate granularity in providing enough different security contexts 
it shouldn't particularly matter. For all we know (and I don't know) RACF 
already does something internally that has more breadth than maximum 8 
character TSO/E user IDs would ordinarily suggest.

Analogously, does it matter much that Microsoft Windows still only 
supports a maximum of 26 single character drive letters (A to Z)? Not 
really, no. Microsoft (and IBM) sidestepped that limitation a long time 
ago by providing an alternate way to refer to disks: \\DiskABC123456\... 
(for example). Older software (that only understands D:\...) doesn't break 
because you can assign and reassign the old drive letters, while newer 
software and user interfaces forge ahead. You then decide whether and how 
quickly you'd like to move forward. I think it's much the same here. There 
are lots of applications and subsystems that run on z/OS that expect user 
IDs (or "user IDs") up to 8 characters maximum, but that's not how you 
must present the world to users. Go ahead and use these LDAP and/or client 
certificate authentication technologies as/where you like. If you have 
z/OS you have the former, and if you have RACF you have the latter, too. 
And if something is missing, ask! (RFEs.)

- - - - - - - - - -
Timothy Sipples
I.T. Architect Executive
Digital Asset & Other Industry Solutions
IBM Z & LinuxONE
- - - - - - - - - -
E-Mail: [email protected]

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