# Relaying denied. IP name lookup failed

## david_guzman

Hi,

I am running Gentoo on a development AMD64 machine. Since a couple of weeks ago I had a lot of problems resolving names. I work in a University, and everyone here has an internal IP address like 10.100.X.Y not valid in internet, as this machine is suppose to be a test platform for apps, I requested a valid IP address like 200.X.Y.Z. Then I got problems resolving names, I was not able to use the internal DNS (10.50.X.Y) and I was forced to use an external DNS (200.H.I.J) which works fine, now comes the current problem....

When I try to eend emails to external recipients I got this error message (no matter the email client)

 550 5.7.1 <david_aaron@softhome.net>... Relaying denied. IP name lookup failed [200.II.JJ.KK)

As I read on sendmail documentation, the cause is:

Missing DNS data....no PTR record for the IP address is found

As I read on the SMTP error message, the lookup fails for the 200.*.*.* address, but my eth0 is set to 10.100.*.*

The question is... setting eth0 to the external IP address 200.*.*.* will solve this problem, is there any alternative as I authenticate using NIS, then I need to use the internal address.

Thanks for the advice

Best regards

                           David

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## dgaffuri

Please, be a little more specific.

 *Quote:*   

> I requested a valid IP address like 200.X.Y.Z

 

Where did this address get bound? You've set an alias for eth0?

 *Quote:*   

>  my eth0 is set to 10.100.*.*

 

Or you have two network cards and one is on the Internet? Or your internal address is natted to the external one by a firewall?

 *Quote:*   

> I was forced to use an external DNS (200.H.I.J)

 

Is the DNS on the Internet or on the internal or DMZ network?

 *Quote:*   

> When I try to eend emails to external recipients I got this error message (no matter the email client)
> 
> 550 5.7.1 <david_aaron@softhome.net>... Relaying denied. IP name lookup failed [200.II.JJ.KK) 

 

Where is your SMTP relay located, on your machine, elsewhere on the internal network or on the internet?

 *Quote:*   

> setting eth0 to the external IP address 200.*.*.*

 

Have you tried or you just suppose it to work?

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## david_guzman

Thanks for the soon reply here is more info:

My current ifconfig:

gendevel david # ifconfig eth0

eth0      Link encap:Ethernet  HWaddr 00:11:09:D9:79:E2  

          inet addr:10.100.1.39  Bcast:10.100.1.255  Mask:255.255.255.0

          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1

          RX packets:6476084 errors:0 dropped:0 overruns:0 frame:0

          TX packets:3646439 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000 

          RX bytes:8458789490 (8066.9 Mb)  TX bytes:271644406 (259.0 Mb)

          Interrupt:16 Base address:0x2f00

I am running an Application Server. In order to be located from outside the University, the netadmin gave provided me with a valid IP address for this machine, this IP is 200.14.68.99. Then at home, I point my browser to 200.14.68.99 and I got the pages and apps I am developing.

Since I have this assigned IP address to be accessed from outside, I have problems resolving, I am not able to resolv using the DNS inside the Univ (10.50.1.15 and 10.50.1.16) the netadmin provided me another external DNS which works fine, so my /etc/resolv.conf is

nameserver 200.14.68.2

instead of the previous setup

nameserver 10.50.1.15

nameserver 10.50.1.16

I have one network card, and the external address is nailed one by one as you wrote

I have no alias for eth0, when I set an alias to the external IP address I am not able to resolv at all

 *Quote:*   

> Where is your SMTP relay located, on your machine, elsewhere on the internal network or on the internet? 

 

Is located on the internal network

I have not set up eth0 to 200.14.68.99

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## dgaffuri

 *Quote:*   

>  I was not able to use the internal DNS (10.50.X.Y) and I was forced to use an external DNS (200.H.I.J) which works fine, now comes the current problem....
> 
> As I read on the SMTP error message, the lookup fails for the 200.*.*.* address, but my eth0 is set to 10.100.*.*

 

Looks as the same problem. It seems that you're seen on your internal network with the public address instead of the private one. You've to check with your network administrator where the NAT is done (must know the exact network topology to diagnose).

Anyway it may be enough to allow sendmail to relay from your specific public IP address.

Sorry that I can't be more helpful.

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