[unisog] HELO and hostname

Cosmin Stejerean cstejerean at gmail.com
Wed Jan 31 20:20:21 GMT 2007


One example of such a host is 123greetings.com

On 1/31/07, Paul Russell <prussell at nd.edu> wrote:
> On Tue, 30 Jan 2007, Bill Martin <BMARTIN at LUC.EDU> wrote:
>  >Some time back, we had saw an influx of mail originating at hosts
>  >providing a "helo" (hostname), where (hostname) usually started with
>  >some numerical value.
>  >
>  >Either I've lost my mind or there use to be an RFC that qualified
>  >"acceptable" host names and if I recall, this ties in with DNS, in that
>  >a hostname (especially in this case) should never start with a number,
>  >only a letter.
>  >
>  >Is this still an acceptable method to reject?  That is, if a host
>  >announces itself as ([0-9]{x}hostname)??
>  >
>  >Any help would be greatly appreciated
>  >-bill-
> >
>
> from RFC 1123 Requirements for Internet Hosts -- Application and Support
>
> > 2.1  Host Names and Numbers
> >
> >      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.
>
> This would seem to indicate that rejection based solely on the fact that
> the hostname starts with a digit (0-9) is probably not valid.
>
> --
> Paul Russell, Senior Systems Administrator
> OIT Messaging Services Team
> University of Notre Dame
> prussell at nd.edu
>
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