Re: Please review netcfg templates for debian-installer

Hi,

On 03/01/2026 at 10:41, Holger Wansing wrote:
> Am 2. Januar 2026 20:48:31 MEZ schrieb Justin B Rye <[email protected]>:
>>
>> hostname(7) implies a trailing hyphen *is* legal, and uppercase
>> letters *aren't*!

hostname(7) does not prohibit a trailing hyphen, but it points to RFC 
1123 (Requirements for Internet Hosts -- Application and Support) which 
points to RFC 952 which does not allow it:

<hname> ::= <name>*["."<name>]
<name>  ::= <let>[*[<let-or-digit-or-hyphen>]<let-or-digit>]

hostname(7) does not explicitly allow upper case letters but it mentions 
case-insensitive match, which implies that case is irrelevant. RFC 952 
and RFC 1034 (Domain Names - Concepts and Facilities) state that no 
distinction is made between upper and lower case.

> @Pascal:
> Seems there are different rules, when it comes to allowed characters and length of FQDN (63 vs. 253).
> 
> Any idea how to deal with that?

This started as a language review but I am afraid we opened a can of 
worms...

In any case, the description should match the rules the code actually 
enforces and vice versa. If we are not happy with current rules, I think 
we should decide on new rules first, then fix the code and update the 
templates accordingly.