[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]

Re: queer dns access problem



Bill Tangren wrote:
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.

OK. Is the /8 netmask a cut and paste error too?

Your trouble could be a routing issue: 10.1.5.58/8 and 10.1.1.46/8 are on the same subnet as far as the network layer is concerned so there is no reason to go to the default route. Thats why I asked for a traceroute too -- or mtr if you have it installed and it will work.

# mtr -rnc 10 DNS.SERVER.IP.ADDRESS

What netmask is the firewall using for the interface?

--
Stephen Carville <scarville landam com>
Systems Engineer
Land America
1.626.667.1450 X1326
#####################################################################
Ad eundum quo nemo ante iit.



[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]