Quick question about valid username characters

[Rick Stevens]

Michael Kearey wrote:
> Alexander Dalloz wrote:
> 
>> Am Di, den 17.02.2004 schrieb Michael Kearey um 09:39:
>>
>>> Hi There,
>>>
>>> I have several multi-user machines running Redhat 8.0. There are 
>>> hundreds of usernames on these machines that have mixture of upper 
>>> and lowercase.
> 
> 
>>> Why the change?
>>
>>
>>
>> I can not confirm that it was a change as I never used uppercase
>> letters, but I can say it was ever a good idea to use just lowercase
>> letters and no special signs. For problems with Sendmail using uppercase
>> letters in usernames see
>>
>> http://www.sendmail.org/faq/section4.html#4.17
> 
> 
> I can confirm there was a change. Several redhat 8.0 boxes I have allow 
> hundreds of uppercase characters usernames. My Fedora box doesn't. 
> Therefore a change happened *somewhere*. Hence why I want to see a 
> changelog that anounces it...
> 
> I still cannot find a reference in any documentation that specifies the 
> valid characters for userID's. (Plain old Unix like usernames I mean).
> 
> I have to take the problem on the chin, I guess. The process of moving 
> users across and translating their usernames etc to all lower case is 
> the simple part. The big problem will be in comunicating the changed 
> usernames to hundreds of users...

I think this can be traced to RFC1274 and the fact that the LDAP COSINE
"userid" attribute (used in LDAP-based authentication) uses
"caseIgnoreStringSyntax" as the equality check--meaning that the
username is case-insensitive.  Upper- and lower-case is insignificant,
"RiCk" is the same as "rICK" is the same as "RICK" is the same as
"rick", you get the idea.  I suspect later versions of PAM and such
now essentially down-case everything.

That's just my opinion--I could be wrong.
----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-      On a scale of 1 to 10 I'd say...  oh, somewhere in there.     -
----------------------------------------------------------------------