Re: queer dns access problem

From: Bill Tangren <bjt(at)usno.navy.mil>
Date: Wed Dec 12 2007 - 16:30:19 EST

> Bill Tangren wrote:

>>>> -----Original Message-----
>>> Some ideas:
>>>
>>> Turn off firewalling if possible.
>>>
>>> Check default route
>>> # ip route list
>>> 10.212.166.0/24 dev eth0  proto kernel  scope link  src 10.212.166.26
>>> 169.254.0.0/16 dev eth0  scope link
>>> default via 10.212.166.1 dev eth0 <----!!!!
>>>
>>> correct if necessary.
>>>
>>> Check for UDP connectivity
>>>
>>> # nmap -PU -p53 DNS.SERVER.IP.ADDRESS

>>>
>>> # traceroute -U DNS.SERVER.IP.ADDRESS
>>
>>
>> OK, this is what is produced on the server that works:
>>
>> *****
>> [root@mach2 X11]# ip route list
>> 169.254.0.0/16 dev eth0 scope link
>> 10.0.0.0/8 dev eth0 proto kernel scope link src 10.1.5.58
>> default via 10.1.1.2 dev eth0

>
> So mach2:eth0 has an IP of 10.1.5.58, right?

Correct.

>

>> [root@mach2 ~]# nmap -PU -p53 10.1.1.6
>> Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2007-12-12 15:33
>> EST
>> Note: Host seems down. If it is really up, but blocking our ping probes,
>> try -P0
>> Nmap run completed -- 1 IP address (0 hosts up) scanned in 2.054 seconds
>>
>> [root@mach2 ~]# nmap -PU -p53 10.1.1.46
>> Starting nmap 3.70 ( http://www.insecure.org/nmap/ ) at 2007-12-12 15:33
>> EST
>> Interesting ports on aurora.timenet.usno.navy.mil (10.1.1.46):
>> PORT STATE SERVICE
>> 53/tcp open domain
>> MAC Address: 00:18:8B:38:28:97 (Unknown)
>>
>> Nmap run completed -- 1 IP address (1 host up) scanned in 0.295 seconds
>>
>> [root@mach2 ~]#
>> *****
>>
>> The server that doesn't looks like this:
>>
>> *****
>> [root@aa-cvs ~]# ip route list
>> 169.254.0.0/16 dev eth0 scope link
>> 10.0.0.0/8 dev eth0 proto kernel scope link src 10.1.5.58
>> default via 10.1.1.2 dev eth0

>
> and aa-cvs:eth0 also has an IP address of 10.1.5.58, right?
>
> See the problem yet?  Same IP address on two nodes?

Sorry. That's a cut and paste error. It is actually 10.1.5.94. I just rechecked.

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Received on Wed Dec 12 16:30:58 2007