sshd: computer name's case must match?

[Bill Stewart]

On Wed, Feb 13, 2019 at 1:25 PM Corinna Vinschen
<corinna-cygwin@cygwin.com> wrote:
> > (a) Domain or computer name portion to the left of the "+" must always
> > be uppercase
>
> No, the case must match the case of the domain or computername.
>
> > (b) Username after "+" sign (or username alone, without "+" sign) must
> > match case exactly
> >
> > Questions:
> >
> > 1. Are the above two statements (a) and (b) complete/correct?
> >
> > 2. With regards to (a), are there any cases where the domain or
> > computer name is not uppercase?
>
> Yes.  In my domain I have four machines using all-lowercase machine
> name for no apparent reason.  One is a Linux machine, one is a
> Windows 7 64 bit, the other two are Windows 8.1 32 and 64 bit machines.
> All others, including the Windows 8 machines, are all uppercase.

The computer or domain name case inconsistency would seem to be a
source of confusion, mainly because on the Windows side we are
case-retentive but not case-sensitive, and it is not immediately
obvious which case will apply in the case of a computer or domain
name.

According to: http://pubs.opengroup.org/onlinepubs/9699919799/ -

> 3.437 User Name - A string that is used to identify a user;
> see also User Database. To be portable across systems
> conforming to POSIX.1-2017, the value is composed of
> characters from the portable filename character set. The
> <hyphen-minus> character should not be used as the first
> character of a portable user name.
>
> 3.282 Portable Filename Character Set
>
> The set of characters from which portable filenames are
> constructed.
>
> 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-minus> characters, respectively.

>From this reference, it seems that a POSIX-compliant username cannot
contain the + character?

So my suggestion is for Cygwin to convert the name part before the +
automatically to upper (or lower) case.

Thoughts?

Thanks!

Bill

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