On Sat, 29 Jun 2002 22:44:13 -0500 Derrick 'dman' Hudson <dsh8290@???> wrote:
>On Sat, Jun 29, 2002 at 07:25:07PM -0400, Dave C. wrote:
>| because neither domain exists (try a whois and/or a dig/nslookup),
>| nor _can_ exist.
well, actually, they can but they shouldn't. it's a very annoying
situation, to be sure. you won't see _ in a first level domain, but it's
depressingly common in windows hostnames, as Derrick indicates below:
>Never underestimate Windows' potential for stupidity. A windows
>machine can be installed and configured with an underscore in the
>host/domain name.
it's common; it dates from the old NETBUEI days when M$ networking was
completely separate from TCP/IP. many old hands at windows were taught that
they should use _.
the most extreme situation i encountered was back around 1997 at a place
that is long since out of business; we had an exchange server that also
had SQL server on it. i was already paranoid about exchange at the time,
and insisted on placing it behind the firewall, with exim hosts outside
for MX hosts relaying mail through the firewall.
our MCSE gave the exchange box a name with an _ in it out of habit. i
pointed out the problem, so he rebuilt the box with - in the name. it
turned out that at the time, SQL server would choke if host names had -
characters in them. the MCSE got to rebuild the box a third time w/o either
_ or - in the host name, all the while cursing hardassed unix admins (such
as myself) who were making him do all this extra work.
i'll leave it for others to consider the fact that changing the host name
in NT 4.0 required that a box be completely rebuilt from scratch. i don't
know if that got fixed in W2K or not. it probably did; a lot of networking
madness in NT got fixed in W2K. M$ admins still tend to put _ in host
names, though, and ones with NT 4.0 experience tend to really not want to
change host names.
> Exchange will then present that name in the EHLO.
>While I don't have direct experience with that, that was the source of
>the complaint regarding the strictness in exim4's helo checking
>option.
it's a difficult problem. i certainly would rather reject _ as it's out of
conformace with the relevant RFCs. on the other hand, as an independent
consultant, people who make that sort of mistake are people who might hire
me to fix their mail problems, so i've chosen to accept _ host names.
richard
--
Richard Welty
rwelty@??? Averill Park Networking
rwelty@??? Unix, Linux, IP Network Engineering, Security
rwelty@??? 518-573-7592
