Re: Name resolution and underscores? www.engadget.com

[Ryo ONODERA <ryo%tetera.org@localhost>]

Hi,

RVP <rvp%SDF.ORG@localhost> writes:

> On Mon, 19 Jan 2026, Paul Ripke wrote:
>
>> Do we check for underscores somewhere in name resolution?
>>
>
> Yes.
>
>> I know that RFC 1035 disallows them from hostnames...
>>
>
> That's it.
>
>> I had a quick browse of our code and nothing obvious stood out.
>>
>
> I think:
>
> src/lib/libc/net/gethnamaddr.c:
>
> gethostbyname() > gethostbyname_r() -> gethostbyname_internal() ->
> nsdispatch() -> _dns_gethtbyname() -> getanswer() ->
>
> name_ok = res_hnok / maybe_ok()
>
> This works--see resolv.conf(5):
>
> # echo 'options no-check-names' >> /etc/resolv.conf

If you use dhcpcd(8), it regenerates /etc/resolv.conf at every invocations.

# echo 'resolv_conf_options=no-check-names' >> /etc/resolvconf.conf

will add 'options no-check-names' to /etc/resolv.conf automatically.

Thank you.

> -RVP

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Ryo ONODERA // ryo%tetera.org@localhost
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