MX smerovany na nestabilnu IP (ADSL, dial)

[Lubos Kaspar]

> Date: Tue, 14 Oct 2003 11:07:50 +0200
> From: Matus UHLAR - fantomas <uhlar at fantomas.sk>
> Subject: Re: MX smerovany na nestabilnu IP (ADSL, dial)
> To: net at cs.felk.cvut.cz
>
> Dan Ohnesorg <Dan at feld.cvut.cz> wrote:
> > ...
> > Mam s tim bohate zkusenosti jak z mych mailserveru, tak treba z koneferenci
> > na linux.cz. Nechavat MX nastaveny na stroj, ktery neni spickove dostupny je
> > podle me bezohlednost.
>
> to je dobry hint. len by sa zislo potom takychto ludi alebo taketo MXka
> penalizovat, resp zacat pisat staznosti a navrhnut RFC.
>
> hladam nejake RFC ale stale nic... v kazdom pripade prvy argument mam.

Jen tak pro ilustraci, ze to nemusi byt uplne nejhorsi pripad. Nedavno
jsem dostal ze stroje, ktery je internetovym SMTP-klientem, hlaseni,
ze nastal timeout na adrese 10.0.0.2 (bounce na spam na neexistujici
adresu), coz mi pripadalo velmi podivne. Nasledne jsem zjistil, ze
domena infini.com ma velmi zvlastni a hlavne absolutne nefunkcni
nastaveni MX, ve kterych se vyskytuji jen intranetove IP-adresy
(RFC 1918):

: $ nslookup -q=soa infini.com|tail +3|grep -v ^$; echo
: Trying DNS
: infini.com
:         origin = infini.com
:         mail addr = root.infini.com
:         serial = 2003092315
:         refresh = 28800 (8 hours)
:         retry   = 14400 (4 hours)
:         expire  = 1200000 (13 days 21 hours 20 mins)
:         minimum ttl = 86400 (1 day)
: infini.com      nameserver = ns1.nill.net
: infini.com      nameserver = ns2.nill.net
: ns1.nill.net    internet address = 209.123.16.20
: ns2.nill.net    internet address = 12.162.49.1
:
: $ nslookup -q=soa infini.com 209.123.16.20|grep -v ^$; echo
: Name Server:  modern.com
: Address:  209.123.16.20
: Trying DNS
: infini.com
:         origin = infini.com
:         mail addr = root.infini.com
:         serial = 2003092315
:         refresh = 28800 (8 hours)
:         retry   = 14400 (4 hours)
:         expire  = 1200000 (13 days 21 hours 20 mins)
:         minimum ttl = 86400 (1 day)
: infini.com      nameserver = ns1.nill.net
: infini.com      nameserver = ns2.nill.net
: ns1.nill.net    internet address = 209.123.16.20
: ns2.nill.net    internet address = 12.162.49.1
:
: $ nslookup -q=mx infini.com 209.123.16.20|grep -v ^$; echo
: Name Server:  modern.com
: Address:  209.123.16.20
: Trying DNS
: infini.com      preference = 10, mail exchanger = 10.0.0.1
: infini.com      preference = 20, mail exchanger = 10.0.0.2
: infini.com      nameserver = ns1.nill.net
: infini.com      nameserver = ns2.nill.net
: ns1.nill.net    internet address = 209.123.16.20
: ns2.nill.net    internet address = 12.162.49.1
:
: $ nslookup -q=a infini.com 209.123.16.20|grep -v ^$
: Name Server:  modern.com
: Address:  209.123.16.20
: Trying DNS
: Name:    infini.com
: Address:  209.123.16.20

Pekne, ze? Pokud MTA dodrzuje smerovani podle MX jako vyhradni
(A jen tehdy, neni-li zadny MX - mam dojem, ze je to podle nejakeho
RFC spravne a aspon sendmail to tak dela), pak neni do infini.com
mozne postu vubec dorucit, tedy ani stiznost na adresu hostmastera
(root at infini.com - viz SOA). :-(
--
Lubos Kaspar