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XMail Forum > Documentation and Knowledge Base > Unable To Get Udp Dns Response


Posted by: bOOster Nov 21 2007, 12:07 PM
XMail 1.25b22
FreeBSD 6.2
Does XMail tryes resolv names directly from root DNS servers or use local server (resolv.conf?)
What protocols (UDP,TCP) resolver uses?

Using tcpdump for discovering close UDP ports - no success. did not see any DNS depending blocking packets..

dig @ns.<domain.ru> mail.<domain.ru> +notcp
works with no problem!!

that is my topology

modem
|
| nat 1:1 -> External Gateway Ext-IP
|
Security Gateway (DMZ Transparent)
|
|
| Ext-IP
External Gateway (Redirect some ports (25,110) to Mail Server mail-Int-IP)
| Int-IP
|
| Mail-Int-IP
Mail Server

Posted by: bOOster Nov 21 2007, 01:53 PM
Ok... goes back to 1.24 Stable - problem dissapears. confused.gif

Posted by: Digdug Nov 21 2007, 04:45 PM
I have the same problem with v1.25-prexx in Windows,
looks like XMail is "waiting" for a response??
It does not happen with all incomming connections.

I already asked davide about this, but it only happened with one incomming IP, but now I see more with the same problem.
Strange thing is, it does not happen all the time...

See previous post: http://xmailforum.homelinux.net/index.php?showtopic=4016

Posted by: bOOster Nov 22 2007, 02:54 AM
I think that 1.24 have the same problem, but from other, single side-

Trying to send message to halykbank.kz domain. XMail said that message have DNS Problem - Server address invalid! But standart FreeBSD resolver have no problem resolving MX and IP address for halykbank.kz domain.

Posted by: hschneider Nov 22 2007, 07:42 AM
Please forward all this directly to Davidel at xmailserver.org. ThanX !

Posted by: Digdug Nov 22 2007, 08:16 AM
Just something about the last domain you mentioned, azimut.kz
They are listed in serveral RBL lists, maybe Custmapslist is causing problems?

halykbank.kz is NOT listed

Posted by: bOOster Nov 23 2007, 10:11 AM
Ok. I think i fix the problem with Davide help.

By default XMail DNS tryes to use root servers for name resolution directly. But if you mail server located behind firewall sometimes this is NOT WORK!!! but a computer resolver (DNS) where XMail hosts works perfectly.

To FIX it:
uncomment SmartDNSHost option and add IP address of local DNS server.

SmartDNSHost "192.168.1.1:udp"

there 192.168.1.1 is a gateway computer (directly connected to internet) with BIND running.

Posted by: Digdug Nov 23 2007, 10:29 AM
Ok, I'll try that, thanks!
I'll post my findings here.

Posted by: Digdug Nov 26 2007, 08:33 PM
Since the change I have had no more DNS "hangs". All XMail queries work properly now.

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