On 07/06/2013 13:45, Michael P. Demelbauer wrote:
On Fri, Jun 07, 2013 at 10:05:41PM +1000, Nikolas Kallis wrote:
As '37.212.64.248' for 'helo' is neither a FQDN nor an address
literal, then is it pointless using 'reject_invalid_helo_hostname'
with 'reject_non_fqdn_helo_host name'?
I have never seen 'reject_invalid_helo_hostname' reject mail, but
from what Postfix's documentation says and from the behaviour of
'reject_non_fqdn_helo_host name', they appear to behave the same
when handling a malformed 'helo'.
Sorry, but allow the dumb question WHY host names are allowed to look
like IP-addresses?
What problem solves this?
Valid hostname syntax is essentially about defining what characters are
permissible. Banning numerics completely would be pointless, as it would
invalidate things like 'server1' and 'host2'.
Remember, a hostname is not necessarily a fully qualified domain nme. So
an all-numeric hostname may simply be a substring of an FQDN.
It's entirely plausible that a large organisation may simply give its
servers hostnames that look like - or even are - IP addresses:
1.2.3.4.server-farm.example.com, 1.2.3.5.server-farm.example.com, etc.
Take off the the common portion of this and you're left with all-numeric
hostnames.
Mark
--
My blog: http://mark.goodge.co.uk
