Userid/passwords

[Mark Brown]

Markus Kuhn wrote on 10/02/01 6:21 AM:

> Neale.Ferguson@softwareAG-usa.com wrote on 2001-02-09 11:27 UTC:
>> Is there a standard/document that defines the characters that are allowed
>> to form a userid or password. Does it vary from locale to locale? What
>> of MBCS systems?
> 
> It's commonly considered to be a good idea to restrict userids in all
> locales to [a-z0-9], because most other ASCII characters have lots of
> special semantics associated with them in zillions of software modules.

Single UNIX Specification says:
user name
A string that is used to identify a user, as described in user database . To
be portable across XSI-conformant systems, the value must be composed of
characters from the portable filename character set. The hyphen should not
be used as the first character of a portable user name.

portable filename character set
The set of characters from which portable filenames are constructed. For a
filename to be portable across implementations conforming to this
specification set and the ISO POSIX-1 standard, it must consist only of the
following characters:


A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
a b c d e f g h i j k l m n o p q r s t u v w x y z
0 1 2 3 4 5 6 7 8 9 . _ -

The last three characters are the period, underscore and hyphen characters,
respectively. The hyphen must not be used as the first character of a
portable filename. Upper- and lower-case letters retain their unique
identities between conforming implementations. In the case of a portable
pathname, the slash character may also be used.


Mark
-- 
Mark S. Brown                                             bmark@us.ibm.com
Senior Technical Staff Member                    512.838.3926  T/L678.3926
AIX and Linux Technologies                           Mark Brown/Austin/IBM
IBM Corporation, Austin, Texas