Date: Wed, 26 Mar 2003 10:18:41 +0000 From: Nick Barnes <Nick.Barnes@pobox.com> To: stable@freebsd.org Subject: Re: Resolver Issues (non valid hostname characters) Message-ID: <3026.1048673921@thrush.ravenbrook.com> In-Reply-To: Message from Terry Lambert <tlambert2@mindspring.com> of "Tue, 25 Mar 2003 17:49:51 PST." <3E81073F.459270AE@mindspring.com>
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At 2003-03-26 01:49:51+0000, Terry Lambert writes:
> David J Duchscher wrote:
> > On Tuesday, March 25, 2003, at 05:03 AM, Terry Lambert wrote:
> >
> > > It's probably not very useful to talk about doing this until
> > > local caching-only name servers on border servers are capable
> > > of handling the 8-bit, as well. For the RFC's that FreeBSD
> > > currently complies with, it's right to be strict about this.
> >
> > I think this is the wrong approach to take with this problem.
> > Linux, Windows, and Solaris do not enforce this restriction. If
> > RFC 952 is being thrown out the window, then why should FreeBSD
> > continue to enforce this restriction? At the moment, the
> > problems I am seeing have little to do with 8-bit data but
> > characters outside of the what RFC 952 allows.
>
> RFC 952 is in effect until a subsequent standards track RFC is
> in effect. Just because Linux allows you to specif host names
> that break other machines, doesn't mean FreeBSD should.
The relevant standard is STD13 (RFC1034 and RFC1035), which does
indeed require LDH for hostnames.
The labels must follow the rules for ARPANET host names. They
must start with a letter, end with a letter or digit, and have as
interior characters only letters, digits, and hyphen. There are
also some restrictions on the length. Labels must be 63
characters or less.
STD3 (RFC1123) modifies this slightly, but still LDH:
The syntax of a legal Internet host name was specified in RFC-952
[DNS:4]. One aspect of host name syntax is hereby changed: the
restriction on the first character is relaxed to allow either a
letter or a digit. Host software MUST support this more liberal
syntax.
In short, underscores in hostnames in the DNS are not permitted by the
internet protocol standards.
That does not necessarily mean that FreeBSD should enforce this
restriction. I'm indifferent to that point.
Nick B
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