Re: Sendmail - how to disable ipv6 AAAA lookups
On Sat, 11 Sep 2004, Robert S wrote:
> I have posted a question recently about sendmail not resolving host names.
> It looks to me as if it is failing to do AAAA lookups.
That'd be a DNS failure - not sendmail... Some resolvers are b0rked
wrt AAAA/A6 lookups :(
> Is is possible to prevent sendmail from trying to do AAAA lookups? This
> might solve the problem.
From: /usr/share/sendmail/cf.README.gz:
Some DNS based rejection lists cause failures if asked
for AAAA records. If your sendmail version is compiled
with IPv6 support (NETINET6) and you experience this
problem, add
define(`DNSBL_MAP', `dns -R A')
From: /usr/share/sendmail/changelog.gz:
Add "use_inet6" as a new ResolverOptions flag to control the
RES_USE_INET6 resolver option. Based on patch from Rick
Nelson of IBM.
Wait... I know that guy... Oh, never mind, that'd be something
akin to:
dnl define(`confBIND_OPTS',
dnl `-use_inet6')dnl #%%%%%
From: /usr/share/sendmail/op/op.txt.gz:
O ResolverOptions=+AAONLY -DNSRCH
turns on the AAONLY (accept authoritative answers
only) and turns off the DNSRCH (search the domain
path) options. Most resolver libraries default
DNSRCH, DEFNAMES, and RECURSE flags on and all others
off. If NETINET6 is enabled, most libraries default
to USE_INET6 as well. You can also include "HasWild-
cardMX" to specify that there is a wildcard MX record
matching your domain; this turns off MX matching when
canonifying names, which can lead to inappropriate
canonifications. Use "WorkAroundBrokenAAAA" when
faced with a broken nameserver that returns SERVFAIL
(a temporary failure) on T_AAAA (IPv6) lookups during
hostname canonification. Notice: it might be neces-
sary to apply the same (or similar) options to sub-
mit.cf too.
Which, in .m4 parlance would be something akin to:
dnl define(`confBIND_OPTS',
dnl `+WorkAroundBrokenAAAA -DNSRCH -DEFNAMES')dnl #%%%%%
> I'm not very keen on recompiling sendmail - I'd like to keep the original
> (debian 3.0) binary for ease of upgrading!! I haven't managed to find
> answers on google groups.
Should be no need....
What is the exact nature of your problem, now that you've apparently
narrowed it down some more ?
--
Rick Nelson
<Marticus> There's too much blood in my caffeine system.
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