reverse dns fails with multiple domains

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reverse dns fails with multiple domains

John Winther
Hi
 
I host 6 mail domains. When I validate my mx configuration online with mxtoolbox.com, I got a fail with reverse dns lookup, my localhostname of the server is bsd5.homedom.local, and that is the domain reverse dns tested, ofcourse it fails hense it is not a public domain, but a local domain.
How do I config postfix to reply with correct banner acording to the public domain tested, 1 of 6 public domain names, and not the localhost name
 
Rgds John
 
 
Malling Ayurveda Produkter
www.soapnut.dk
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Re: reverse dns fails with multiple domains

Wietse Venema
John WInther:

> Hi
>
> I host 6 mail domains. When I validate my mx configuration online
> with mxtoolbox.com, I got a fail with reverse dns lookup, my
> localhostname of the server is bsd5.homedom.local, and that is
> the domain reverse dns tested, ofcourse it fails hense it is not
> a public domain, but a local domain.
> How do I config postfix to reply with correct banner acording to
> the public domain tested, 1 of 6 public domain names, and not the
> localhost name

The "mail server" name is set with the main.cf myhostname parameter.

I suggest that you also read the following:
http://www.postfix.org/BASIC_CONFIGURATION_README.html

        Wietse
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Re: reverse dns fails with multiple domains

John Winther
Thanks for info, I am aware of  the manual and I have previus tryed to
change the myhostname to soapnut.dk, I still got the reverse dns error.
I gave me an idear to reverse resolve the ip address registred in mx, and
the reply from that test was the dns name of my internet access.
0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk, when i put that in as
myhostname the reverse dns lookup reply with success.
Thanks

----- Original Message -----
From: "Wietse Venema" <[hidden email]>
To: "Postfix users" <[hidden email]>
Sent: Saturday, March 06, 2010 1:33 PM
Subject: Re: reverse dns fails with multiple domains


> John WInther:
>> Hi
>>
>> I host 6 mail domains. When I validate my mx configuration online
>> with mxtoolbox.com, I got a fail with reverse dns lookup, my
>> localhostname of the server is bsd5.homedom.local, and that is
>> the domain reverse dns tested, ofcourse it fails hense it is not
>> a public domain, but a local domain.
>> How do I config postfix to reply with correct banner acording to
>> the public domain tested, 1 of 6 public domain names, and not the
>> localhost name
>
> The "mail server" name is set with the main.cf myhostname parameter.
>
> I suggest that you also read the following:
> http://www.postfix.org/BASIC_CONFIGURATION_README.html
>
> Wietse

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Re: reverse dns fails with multiple domains

Stan Hoeppner
John WInther put forth on 3/6/2010 12:57 PM:
> Thanks for info, I am aware of  the manual and I have previus tryed to
> change the myhostname to soapnut.dk, I still got the reverse dns error.
> I gave me an idear to reverse resolve the ip address registred in mx,
> and the reply from that test was the dns name of my internet access.
> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk, when i put that in as
> myhostname the reverse dns lookup reply with success.

RFC does not dictate that your forward and reverse dns names match.  It does
dictate that a domain name must be valid.  Anything ending in .local is not
valid.

I'd suggest against using

0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk

as your Postfix HELO name.  Use a hostname based on one of your mail domains
instead.  Some sites will block SMTP servers that HELO with such a generic
hostname as that above.

--
Stan
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Re: reverse dns fails with multiple domains

mouss-4
Stan Hoeppner a écrit :

> John WInther put forth on 3/6/2010 12:57 PM:
>> Thanks for info, I am aware of  the manual and I have previus tryed to
>> change the myhostname to soapnut.dk, I still got the reverse dns error.
>> I gave me an idear to reverse resolve the ip address registred in mx,
>> and the reply from that test was the dns name of my internet access.
>> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk, when i put that in as
>> myhostname the reverse dns lookup reply with success.
>
> RFC does not dictate that your forward and reverse dns names match.  It does
> dictate that a domain name must be valid.  Anything ending in .local is not
> valid.
>
> I'd suggest against using
>
> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk
>
> as your Postfix HELO name.  Use a hostname based on one of your mail domains
> instead.  Some sites will block SMTP servers that HELO with such a generic
> hostname as that above.

true. better use soapnut.dk in myhostname. Although I doubt this will
help a lot:

- "some" sites will block if the PTR is generic... too many zombies out
there...

- OP's reverse DNS is borked:
$ host 188.183.91.18
18.91.183.188.in-addr.arpa domain name pointer
0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
$ host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
Host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk. not found:
3(NXDOMAIN)

so OP not only has a "generic" name, but it doesn't resolve back to the
IP. If he can get his ISP to fix his reverse (preferably using a custom
reverse), then maybe things will get better.



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Re: reverse dns fails with multiple domains

Stan Hoeppner
In reply to this post by Stan Hoeppner
Greg A. Woods put forth on 3/6/2010 2:58 PM:
> At Sat, 06 Mar 2010 14:42:13 -0600, Stan Hoeppner <[hidden email]> wrote:
> Subject: Re: reverse dns fails with multiple domains
>>
>> RFC does not dictate that your forward and reverse dns names match.
>
> Common sense and common decency do though -- since if the forward and
> reverse names are not all orthogonal then the DNS lies, either by
> omission, or outright.

Apparently you've missed past discussions here showing some examples of why
this can be neither practical or desirable in some situations.

> For every hostname pointing at an IP address, there should be a
> corresponding PTR for that address pointing back at the hostname.

When you say hostname, are you talking A record?  Are you talking all IPs in
general, or only MX hosts, or SMTP sending hosts?  Does a web server ever
need a PTR?  Do any web browsers ever look up a host via PTR?  No.  So why
should a web server have a PTR?

> There's no real excuse for mis-matched forward and reverse DNS.  If
> you're going to show your reverse DNS to the world, then do it right.

A web server with a single IP address hosting 378 vitural domains.  Should
it have 379 PTRs?  One for the host itself and one for each virtual domain?
 Of course not.

A mail server with a single IP address hosting 378 mail domains?  Should it
have 379 PTRs?  One for the host itself and one for each virtual MX domain?
 Of course not.  In this case, the DNS infrastructure isn't smart enough to
return matching records even though they do exist, so why bother?

You're living in a "perfect" world where everything has a 1:1 relationship
in DNS.  In the real world, this isn't the case, and probably never will be.

I argued your position for years until I was blue in the face.  You know
what it gained me?  A blue face.  Nothing else.

BTW, please keep list correspondence on list.  I don't see any reason why
your reply needed to be off list.

--
Stan
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Re: reverse dns fails with multiple domains

Stan Hoeppner
In reply to this post by mouss-4
mouss put forth on 3/6/2010 3:01 PM:

> so OP not only has a "generic" name, but it doesn't resolve back to the
> IP. If he can get his ISP to fix his reverse (preferably using a custom
> reverse), then maybe things will get better.

I assume this is difficult if not impossible, given it appears residential,
so I recommended fixing what he could, the HELO name.  And yes, many sites
will block that PTR string at client name lookup as well as HELO lookup, but
I think the probability is higher with HELO.

--
Stan
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Re: reverse dns fails with multiple domains

John Winther
In reply to this post by mouss-4
My primary concern is that some mailservers deny sending mail to my domains
if the reverse dns lookup fails. If I set myhostname to one of my public
domains, the reply string from HELO is ok, but the reverse dns lookup fails,
If not possible to satisfy both issues what is best configuration?.

----- Original Message -----
From: "mouss" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, March 06, 2010 10:01 PM
Subject: Re: reverse dns fails with multiple domains


> Stan Hoeppner a écrit :
>> John WInther put forth on 3/6/2010 12:57 PM:
>>> Thanks for info, I am aware of  the manual and I have previus tryed to
>>> change the myhostname to soapnut.dk, I still got the reverse dns error.
>>> I gave me an idear to reverse resolve the ip address registred in mx,
>>> and the reply from that test was the dns name of my internet access.
>>> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk, when i put that in as
>>> myhostname the reverse dns lookup reply with success.
>>
>> RFC does not dictate that your forward and reverse dns names match.  It
>> does
>> dictate that a domain name must be valid.  Anything ending in .local is
>> not
>> valid.
>>
>> I'd suggest against using
>>
>> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk
>>
>> as your Postfix HELO name.  Use a hostname based on one of your mail
>> domains
>> instead.  Some sites will block SMTP servers that HELO with such a
>> generic
>> hostname as that above.
>
> true. better use soapnut.dk in myhostname. Although I doubt this will
> help a lot:
>
> - "some" sites will block if the PTR is generic... too many zombies out
> there...
>
> - OP's reverse DNS is borked:
> $ host 188.183.91.18
> 18.91.183.188.in-addr.arpa domain name pointer
> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
> $ host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
> Host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk. not found:
> 3(NXDOMAIN)
>
> so OP not only has a "generic" name, but it doesn't resolve back to the
> IP. If he can get his ISP to fix his reverse (preferably using a custom
> reverse), then maybe things will get better.
>
>
>

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Re: reverse dns fails with multiple domains

Stan Hoeppner
John WInther put forth on 3/6/2010 4:18 PM:
> My primary concern is that some mailservers deny sending mail to my domains
> if the reverse dns lookup fails. If I set myhostname to one of my public
> domains, the reply string from HELO is ok, but the reverse dns lookup
> fails,
> If not possible to satisfy both issues what is best configuration?.

I still don't understand what reverse dns failure you're talking about.
Please paste the failure info page or link from mx toolbox so we understand
exactly what you're talking about.

--
Stan
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Re: reverse dns fails with multiple domains

/dev/rob0
In reply to this post by John Winther
Top-posting fixed. Please don't top-post here, thanks.

> ----- Original Message ----- From: "mouss" <[hidden email]>
>> so OP not only has a "generic" name, but it doesn't resolve back
>> to the IP. If he can get his ISP to fix his reverse (preferably
>> using a custom reverse), then maybe things will get better.

On Sat, Mar 06, 2010 at 11:18:32PM +0100, John WInther wrote:
> My primary concern is that some mailservers deny sending mail to my
> domains if the reverse dns lookup fails. If I set myhostname to one
> of my public domains, the reply string from HELO is ok, but the
> reverse dns lookup fails, If not possible to satisfy both issues
> what is best configuration?.

Of course it's possible, just as Mouss said. Have the ISP set your
custom reverse name (PTR) for your IP address. Use that name,
whatever it was that you decide on, as $myhostname in Postfix.

If the ISP can't/won't do that, you can't run a serious MTA there.
Use a relayhost or shop around for other options. Hobbyists might
find a VPS hosting service like Linode.com to be more affordable than
business-class Internet service.
--
    Offlist mail to this address is discarded unless
    "/dev/rob0" or "not-spam" is in Subject: header
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Re: reverse dns fails with multiple domains

John Winther
In reply to this post by John Winther
running smtp test on soapnut.dk


smtp:188.183.91.18     smtp

220 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk ESMTP Postfix


 Not an open relay.
 0 seconds - Good on Connection time
 0.702 seconds - Good on Transaction time
 OK - 188.183.91.18 resolves to
0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk
 OK - Reverse DNS matches SMTP Banner


when I change nyhostname in postfix to soapnut.dk :

220 soapnut.dk ESMTP Postfix


 Not an open relay.
 0 seconds - Good on Connection time
 0.733 seconds - Good on Transaction time
 OK - 188.183.91.18 resolves to
 Warning - Reverse DNS does not match SMTP Banner

Do I set myhostname in postfix to
0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk or to soapnut.dk ?


----- Original Message -----
From: "John WInther" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, March 06, 2010 11:18 PM
Subject: Re: reverse dns fails with multiple domains


> My primary concern is that some mailservers deny sending mail to my
> domains
> if the reverse dns lookup fails. If I set myhostname to one of my public
> domains, the reply string from HELO is ok, but the reverse dns lookup
> fails,
> If not possible to satisfy both issues what is best configuration?.
>
> ----- Original Message -----
> From: "mouss" <[hidden email]>
> To: <[hidden email]>
> Sent: Saturday, March 06, 2010 10:01 PM
> Subject: Re: reverse dns fails with multiple domains
>
>
>> Stan Hoeppner a écrit :
>>> John WInther put forth on 3/6/2010 12:57 PM:
>>>> Thanks for info, I am aware of  the manual and I have previus tryed to
>>>> change the myhostname to soapnut.dk, I still got the reverse dns error.
>>>> I gave me an idear to reverse resolve the ip address registred in mx,
>>>> and the reply from that test was the dns name of my internet access.
>>>> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk, when i put that in as
>>>> myhostname the reverse dns lookup reply with success.
>>>
>>> RFC does not dictate that your forward and reverse dns names match.  It
>>> does
>>> dictate that a domain name must be valid.  Anything ending in .local is
>>> not
>>> valid.
>>>
>>> I'd suggest against using
>>>
>>> 0xbcb75b12.cpe.ge-1-1-0-1112.customer.tele.dk
>>>
>>> as your Postfix HELO name.  Use a hostname based on one of your mail
>>> domains
>>> instead.  Some sites will block SMTP servers that HELO with such a
>>> generic
>>> hostname as that above.
>>
>> true. better use soapnut.dk in myhostname. Although I doubt this will
>> help a lot:
>>
>> - "some" sites will block if the PTR is generic... too many zombies out
>> there...
>>
>> - OP's reverse DNS is borked:
>> $ host 188.183.91.18
>> 18.91.183.188.in-addr.arpa domain name pointer
>> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
>> $ host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
>> Host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk. not found:
>> 3(NXDOMAIN)
>>
>> so OP not only has a "generic" name, but it doesn't resolve back to the
>> IP. If he can get his ISP to fix his reverse (preferably using a custom
>> reverse), then maybe things will get better.
>>
>>
>>
>

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Re: reverse dns fails with multiple domains

Daniel V. Reinhardt
----- Original Message ----

> From: John WInther <[hidden email]>
> To: [hidden email]
> Sent: Sat, March 6, 2010 11:13:17 PM
> Subject: Re: reverse dns fails with multiple domains
>
> running smtp test on soapnut.dk
>
>
> smtp:188.183.91.18     smtp
>
> 220 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk ESMTP Postfix
>
>
> Not an open relay.
> 0 seconds - Good on Connection time
> 0.702 seconds - Good on Transaction time
> OK - 188.183.91.18 resolves to
> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk
> OK - Reverse DNS matches SMTP Banner
>
>
> when I change nyhostname in postfix to soapnut.dk :
>
> 220 soapnut.dk ESMTP Postfix
>
>
> Not an open relay.
> 0 seconds - Good on Connection time
> 0.733 seconds - Good on Transaction time
> OK - 188.183.91.18 resolves to
> Warning - Reverse DNS does not match SMTP Banner
>
> Do I set myhostname in postfix to
> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk or to soapnut.dk ?
>

Here is mine:

 Not an open
relay.
 0 seconds -
Good on Connection time
 0.234
seconds - Good on Transaction time
 OK -
173.73.4.107 resolves to
 Warning -
Reverse DNS does not match SMTP Banner

I have no issues with sending email to anyone.

Daniel Reinhardt
Website: www.cryptodan.com
Email:
[hidden email]


     
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Re: reverse dns fails with multiple domains

mouss-4
In reply to this post by John Winther
John WInther a écrit :

> running smtp test on soapnut.dk
>
>
> smtp:188.183.91.18     smtp
>
> 220 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk ESMTP Postfix
>
>
> Not an open relay.
> 0 seconds - Good on Connection time
> 0.702 seconds - Good on Transaction time
> OK - 188.183.91.18 resolves to
> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk
> OK - Reverse DNS matches SMTP Banner
>
>
> when I change nyhostname in postfix to soapnut.dk :
>
> 220 soapnut.dk ESMTP Postfix
>
>
> Not an open relay.
> 0 seconds - Good on Connection time
> 0.733 seconds - Good on Transaction time
> OK - 188.183.91.18 resolves to
> Warning - Reverse DNS does not match SMTP Banner
>

This is a bogus test. forget about people who do random tests. The site
developer doesn't understand what need to match...

see my previous mail for your reverse dns issue. but this has nothing to
do with your banner (or with anything that you could fix in main.cf or
any postfix confg file). Only your ISP can help.


> Do I set myhostname in postfix to
> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk or to soapnut.dk ?

as said before, the latter is better. you may get a little more chances
to get your mail out.

PS. As Rob said, please do not top post. put your answers after the text
you reply to.


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Re: reverse dns fails with multiple domains

mouss-4
In reply to this post by Stan Hoeppner
Stan Hoeppner a écrit :
> mouss put forth on 3/6/2010 3:01 PM:
>
>> so OP not only has a "generic" name, but it doesn't resolve back to the
>> IP. If he can get his ISP to fix his reverse (preferably using a custom
>> reverse), then maybe things will get better.
>
> I assume this is difficult if not impossible, given it appears residential,

Any ISP should configure PTRs for their IPv4 space. but I guess you are
talking about the other part (custom rdns). Some ISPs provide custom
reverse for free (ex: free.fr). others provide it for a fee (may or may
not be ok for OP).

but in any case, anyone can tell the ISP that not setting up reverse DNS
for IPv4 space is dumb.

> so I recommended fixing what he could, the HELO name.  And yes, many sites
> will block that PTR string at client name lookup as well as HELO lookup, but
> I think the probability is higher with HELO.
>

Agreed.

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Re: reverse dns fails with multiple domains

mouss-4
In reply to this post by Stan Hoeppner
Stan Hoeppner a écrit :
> [snip]
> A web server with a single IP address hosting 378 vitural domains.  Should
> it have 379 PTRs?  One for the host itself and one for each virtual domain?
>  Of course not.
>
> A mail server with a single IP address hosting 378 mail domains?  Should it
> have 379 PTRs?  One for the host itself and one for each virtual MX domain?
>  Of course not.  In this case, the DNS infrastructure isn't smart enough to
> return matching records even though they do exist, so why bother?

Stan, you're confused. What is "asked" for is:

- if an IP is used to send mail, then it should have at least one PTR
(preferably only one)
- _any_ PTR returned for this IP should resolve back to the IP (the
_nay_ is because no server is going to spend hours trying to resolve
3000 PTRs...).

This has nothing to do with virtual hosts and the like. As you can
guess, imlil.netoyen.net is hosting many domains. but the IP has only
one PTR and that PTR resolves back to that IP. (and the box has multiple
IPs too, which correspond to various hostnames...).

When you run a "server" (something that listens to requests), you don't
care about reverse DNS. so www.example.com only needs to resolve (that's
what the browser does). nobody is going to resolve the IP back to a name
(that would be stupid).

When you run a "client" (something that initiates a TCP connection...),
you'd better have "FCrDNS" (IP -> name ->IP returns original IP).

well, all this may go away with IPv6. but as of IPv4, it is common
practice... (I don't know if this is still the case, but gandi.net won't
allow you to query their whois if you have that "wrong").


> [snip]

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Re: reverse dns fails with multiple domains

Stan Hoeppner
mouss put forth on 3/6/2010 6:03 PM:

> Stan Hoeppner a écrit :
>> [snip]
>> A web server with a single IP address hosting 378 vitural domains.  Should
>> it have 379 PTRs?  One for the host itself and one for each virtual domain?
>>  Of course not.
>>
>> A mail server with a single IP address hosting 378 mail domains?  Should it
>> have 379 PTRs?  One for the host itself and one for each virtual MX domain?
>>  Of course not.  In this case, the DNS infrastructure isn't smart enough to
>> return matching records even though they do exist, so why bother?
>
> Stan, you're confused. What is "asked" for is:

I'm not confused at all mouss.  I was mocking Greg with an absurd example of
what he espouses here:

Greg A. Woods put forth on 3/6/2010 2:58 PM:

> For every hostname pointing at an IP address, there should be a
> corresponding PTR for that address pointing back at the hostname.

My example exactly matches what he says.  What he says is incorrect.  I was
drawing attention to his absurd suggestion with an example of absurdity.

--
Stan
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Re: reverse dns fails with multiple domains

mouss-4
Stan Hoeppner a écrit :

> mouss put forth on 3/6/2010 6:03 PM:
>> Stan Hoeppner a écrit :
>>> [snip]
>>> A web server with a single IP address hosting 378 vitural domains.  Should
>>> it have 379 PTRs?  One for the host itself and one for each virtual domain?
>>>  Of course not.
>>>
>>> A mail server with a single IP address hosting 378 mail domains?  Should it
>>> have 379 PTRs?  One for the host itself and one for each virtual MX domain?
>>>  Of course not.  In this case, the DNS infrastructure isn't smart enough to
>>> return matching records even though they do exist, so why bother?
>> Stan, you're confused. What is "asked" for is:
>
> I'm not confused at all mouss.  I was mocking Greg with an absurd example of
> what he espouses here:
>
> Greg A. Woods put forth on 3/6/2010 2:58 PM:
>
>> For every hostname pointing at an IP address, there should be a
>> corresponding PTR for that address pointing back at the hostname.
>
> My example exactly matches what he says.  What he says is incorrect.  I was
> drawing attention to his absurd suggestion with an example of absurdity.
>

Ah sorry. I read it the other way...



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Re: reverse dns fails with multiple domains

Jesper Dybdal-2
In reply to this post by mouss-4
On Sat, 06 Mar 2010 22:01:14 +0100, mouss <[hidden email]> wrote:

>- OP's reverse DNS is borked:
>$ host 188.183.91.18
>18.91.183.188.in-addr.arpa domain name pointer
>0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
>$ host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
>Host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk. not found:
>3(NXDOMAIN)
>
>so OP not only has a "generic" name, but it doesn't resolve back to the
>IP. If he can get his ISP to fix his reverse (preferably using a custom
>reverse), then maybe things will get better.

The ISP in question is the largest Danish ISP, TDC, of which I am also a
customer.  They are generally quite good at having consistent forward
and reverse DNS records.

I expect that if the OP points out the missing A record for
"0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk." in a mail to
"hostmaster at tele dot dk", then they will fix it.  And that will
probably solve the problem, regardless of the HELO name.

Alternatively, since I suspect from the reverse DNS name that the OP's
connection is a "Pro" grade ADSL product, he can probably get TDC to set
the reverse DNS of his IP address to his own name ("soapnut.dk.") simply
by asking TDC at that same mail address.
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Re: reverse dns fails with multiple domains

mouss-4
Jesper Dybdal a écrit :

> On Sat, 06 Mar 2010 22:01:14 +0100, mouss <[hidden email]> wrote:
>
>> - OP's reverse DNS is borked:
>> $ host 188.183.91.18
>> 18.91.183.188.in-addr.arpa domain name pointer
>> 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
>> $ host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
>> Host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk. not found:
>> 3(NXDOMAIN)
>>
>> so OP not only has a "generic" name, but it doesn't resolve back to the
>> IP. If he can get his ISP to fix his reverse (preferably using a custom
>> reverse), then maybe things will get better.
>
> The ISP in question is the largest Danish ISP, TDC, of which I am also a
> customer.  They are generally quite good at having consistent forward
> and reverse DNS records.

well, lesseee

$  host 188.183.91.18
18.91.183.188.in-addr.arpa domain name pointer
0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
$ host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk.
Host 0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk. not found:
3(NXDOMAIN)

so rdns is borked. chances are this is intentional...

compare this with the 2d french ISP situation:

$ host 82.239.111.7
7.111.239.82.in-addr.arpa domain name pointer
mon75-10-82-239-111-7.fbx.proxad.net.
$ host mon75-10-82-239-111-7.fbx.proxad.net
mon75-10-82-239-111-7.fbx.proxad.net has address 82.239.111.7

so rdns is correctly configured.

now all this is "generic" names. so compare with (which the said second
ISP allows you to configure using your web UI, for no fee):

$ host 82.239.111.75
75.111.239.82.in-addr.arpa domain name pointer ouzoud.netoyen.net.
$ host ouzoud.netoyen.net.
ouzoud.netoyen.net has address 82.239.111.75

anyway, back to tele.dk, I have
/^0x\d+\.cpe\..*\.customer\.tele\.dk$/
        REJECT generic hostname. Please use your ISP relay or fix your
hostname.


> I expect that if the OP points out the missing A record for
> "0xbcb75b12.cpe.ge-1-1-0-1112.hcnqu2.customer.tele.dk." in a mail to
> "hostmaster at tele dot dk", then they will fix it.  And that will
> probably solve the problem, regardless of the HELO name.

since you are a customer, it would be good if you contact them to fix
their rdns (I wonder if it not intentional). and more importantly, I'd
like to know if they provide custom rdns freely or at least for a
reasonable price.

>
> Alternatively, since I suspect from the reverse DNS name that the OP's
> connection is a "Pro" grade ADSL product, he can probably get TDC to set
> the reverse DNS of his IP address to his own name ("soapnut.dk.") simply
> by asking TDC at that same mail address.

not sure. here in .fr, the major ISP is Orange, and you can only get a
custome rdns if you pay for (while it's free with the 2d ISP, which is
free.fr/proxad). but Orange block port 25 (well, not sure it's been
completed...).