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DNS for Fedora 18

Posted on 2013-06-04
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Last Modified: 2013-06-06
Hi Experts,
I have a Fedora 18 in DMZ with the external dns server.
But when it sends me a log message via an email, it should go to the SMTP server where is in inside network. I already open the smtp port on the firewall.
When I did nslookup, it tries to resolve the smtp server using the external DNS.
How can it specify this computer to go to the internal DNS when it tries to send email?
The smtp server is working just fine with all other servers.
Thanks in advance.
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Question by:Ksean
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Expert Comment

by:Mazdajai
ID: 39219512
Do you have internal DNS server defined in your /etc/resolv.conf?
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Author Comment

by:Ksean
ID: 39219577
yes.

search local.com
nameserver 198.6.1.4
nameserver 198.6.1.5

Is there any other location that I have to modify to resovle the internal host names while the external DNS are specified in ifcfg-eth0?
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LVL 21

Expert Comment

by:Mazdajai
ID: 39219609
Sounds like you have NetworkManager running.

You can check your ifcfg files if this is present NM_CONTROLLED=YES. If NM is running, NM will take the DNS servers you defined in ifcfg-xxx and overwrite them into resolv.conf.

So the answer is updating the ifcfg-eth0 if you have NM running, else you have to edit resolv.conf manually.
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Author Comment

by:Ksean
ID: 39219642
NM is running and I update resolve.conf file manually but I haven't restarted NM yet.
Will it be OK after restarting NM?
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LVL 21

Expert Comment

by:Mazdajai
ID: 39219673
You need to update the network scripts - ifcfg-eth0 if you have NM running, NM may overwrite the entry in resolv.conf.

DNS1=1.2.3.4
DNS2=1.2.3.5

Open in new window

After updating the network scripts, run. Be aware that it will disrupt the connection of the server.
service NetworkManager stop
service NetworkManager start

Open in new window

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Author Comment

by:Ksean
ID: 39219911
ifcfg has still dns1=198.6.1.4 and dns2=198.6.1.5 from the biginning. These are the external DNS of verizon. I cannot have an internal DNS because this is in DMZ. Do I need anything else?
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LVL 21

Expert Comment

by:Mazdajai
ID: 39219922
Can you clarify the following?

How can it specify this computer to go to the internal DNS when it tries to send email?
I cannot have an internal DNS because this is in DMZ.
0
 

Author Comment

by:Ksean
ID: 39220218
When one of the linux in DMZ sends me where in Inside network a log every day, it uses a SMTP server where is in Inside network so I opened port 25 between the DMZ and Inside.
The linux has the external DNS servers which is 198.6.1.5 When the linux sends an email using the Inside SMTP server, it tries to resolve the host name by the external DNS which cannot be resolved.
This what i need.
The linux should be resolved the host name internally when it sends me an email and all others should be resolved by the external DNS.
I hope this makes sense.
I will try to restart NM since I already changed the resolv.conf file to see how it goes.
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Accepted Solution

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Mazdajai earned 500 total points
ID: 39220535
For your scenario, one way I can think of is to use local host file.
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Author Closing Comment

by:Ksean
ID: 39225830
Thanks
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