Allow underscores in DNS names

[Giorgos Keramidas]

On 2003-03-30 16:16, Dag-Erling Sm?rgrav wrote:
>"M. Warner Losh" <imp at bsdimp.com> writes:
>> True.  However, they are still relevant today.  '_' is illegal in DNS
>> names
>
> Says the RFC.  IIRC, BIND traditionally did not enforce this, though
> it does now for A records in master zones unless you change the
> "check-names" setting (it seems to allow it for TXT records though).
>
>>        is rejected by the majority of hosts on the internet
>
> Wrong.  We (*BSD) are pretty much the only ones not to accept
> underscores in host names.  I've tested Windows XP, Solaris 8 and
> Linux 2.4.18; feel free to try 'ping under_score.ofug.org' on other
> systems and report your findings here.

If everyone else supports underscores (I've only tested Solaris and
Linux 2.4.20), then perhaps, just for the sake of interoperability
with other systems, we should too.

Even in Linux (where it's accepted as a valid hostname by the
resolver) it's annoying when one sees the warning it causes:

: igloo# host under_score.ofug.org
: under_score.ofug.org    A       127.0.0.1
:  !!! under_score.ofug.org A record has illegal name

Giorgos.