Sendmail on a LAN

JD jd1008 at
Wed Aug 18 03:28:53 UTC 2010

  On 08/17/2010 07:50 PM, Daniel B. Thurman wrote:
>   On 08/17/2010 05:10 PM, JD wrote:
>>    On 08/17/2010 04:56 PM, Craig White wrote:
>>> On Tue, 2010-08-17 at 16:47 -0700, JD wrote:
>>>> On 08/17/2010 03:35 PM, Daniel B. Thurman wrote:
>>>>>     On 08/17/2010 02:25 PM, JD wrote:
>>>>>>      On 08/17/2010 01:27 PM, Gordon Messmer wrote:
>>>>>>> On 08/17/2010 09:33 AM, JD wrote:
>>>>>>>> Re:  a.b.c.d ==>
>>>>>>>> and ==>      a.b.c.d
>>>>>>>> does not seem to apply to the google smtp server I use for Thunderbird.
>>>>>>> You did your test entirely backward.  You did a forward lookup first,
>>>>>>> and then checked the PTR of the IP which was returned.  There is no
>>>>>>> requirement for a PTR to match every hostname that resolves to its IP
>>>>>>> address.
>>>>>>> Let's finish your test:
>>>>>>> $ host
>>>>>>> is an alias for
>>>>>>> has address
>>>>>>> The result of this test merely identifies an IP address.  Now, let's
>>>>>>> test to validate that the IP returns a PTR that resolves to the same IP:
>>>>>>> $ host
>>>>>>> domain name pointer
>>>>>>> $ host
>>>>>>> has address
>>>>>>> Yep, totally valid.  That IP address has a PTR record, and the hostname
>>>>>>> contained in that PTR resolves back to the same IP address.  This host
>>>>>>> is properly configured.
>>>>>>>> So, Thunderbird client does not seem to mind that
>>>>>>>> reverse lookup does not match the name
>>>>>>> Clients rarely do.  It's the servers to which you're going to try to
>>>>>>> deliver mail that will mind.
>>>>>> I see! Thanks for the heads up!
>>>>>> At any rate, I am having serious problem with an unwieldy router.
>>>>>> I just posted a message about that.
>>>>> 1) Make sure your ISP is not interfering with your traffic, to direct
>>>>>        all traffic to/from your primary router static IP address.  You can
>>>>>        call them and ask about it.  Mine was very helpful and cooperative
>>>>>        ( and their rates are good compared with many I have
>>>>>        checked.
>>>>> 2) If your ISP router allows, you might be able to set up your router
>>>>>        as a pass-through router forwarded to a more robust FW router,
>>>>>        or directly to your fedora box to handle the public firewall/NAT.
>>>>>        I have a hardware firewall appliance (SonicWall), so my dumb ISP
>>>>>        provided router is simply a pass-through router to SonicWall.
>>>>> 3) You state that you have static public IP addresse(s), but do
>>>>>        you have a domain name?  If so, make sure at the domain
>>>>>        name provider (DNP) website that you define your name
>>>>>        server addresses and most DNP require at minimum, 2
>>>>>        name servers. I set my name servers to ns1.mydomain.x1
>>>>>        and ns2.mydomain.x2 which is handled by my own domain
>>>>>        name servers. Just make sure you configure your name servers
>>>>>        properly (forwarders to your ISP name servers).
>>>>>        Make sure your sendmail is also properly configured.  Since
>>>>>        you use Thunderbird as I do, it is IMAP capable, so sendmail
>>>>>        needs special setup to support IMAP/Mailldir (as opposed to mbox)
>>>>>        handling and I use dovecot as my IMAP server As for the many
>>>>>        spams that DO come through, I use sendmail for that - I get VERY
>>>>>        MINIMAL spams - and this requires that you carefully and properly
>>>>>        setup your sendmail configuration.
>>>>> Once you get though all of this and to make it work, it is well worth it,
>>>>> at least it is for me.
>>>>> FWIW,
>>>>> Dan
>>>> I have done all that. Really. ISP (at&t) has unblocked port 25
>>>> per my request. So I can indeed smtp out. But when an smtp request
>>>> comes in to the router, the router seems to get confused as to the
>>>> session type - and calls is an Unknown session type, and blocks
>>>> the request. Router has no settings as to what session types are
>>>> and what types can be blocked, and what types can be accepted.
>>>> Session types are opaque to the user as far as configuration goes.
>>>> There are no means to admin session types.
>>>> What else can one expect from a thuggish isp?
>>> ----
>>> configure your router to forward inward port 25 (TCP) to your mail
>>> server. Shouldn't be that hard to do.
>>> Craig
>> I have done more than that.
>> For all incoming requests (ports 1-65535) are forwarded to my fedora
>> machine,
>> for both tcp and udp.
>> Problem seems to be the firmware of the router (made by 2wire for at&t).
>> it is absulutely the most horible router firmware I have ever used.
>> here's an example of it's brain dead operation:
>> src= dst= ipprot=6 sport=49645 dport=25 Unknown
>> inbound session stopped
>> And yet, it is confugured to ACCEPT smtp packets.
>> It makes the lame excuse it does not know the inbound session?
>> What a bunch of unmentionable stuff!!
> What is this router you are talking about?  Are
> you sure it isn't broken or is in need of a firmware
> update?  I have no clue what this router is that you
> are dealing with...  care to provide a bit of details
> since you are bitterly complaining about it?
> If all else, consider getting another router that you
> know how to configure?
Hi Dan,
probably you did not catch the earlier stuff on this thread....
The router is a 2-wire, but AT&T sells it as their Uverse
router, which handles internet and TV.
You will not find this on the market, because I do not
know which 2-wire model it is. People who have at&t
Uverse know what I'm talking about - but then perhaps
at&t uses different routers in different market zones.

At any rate, I got things to almost work...
so I am still at it....



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