bind9 gone crazy!

sloganyart · 06-17-2007, 09:07 PM

Hi there, I have been troubleshooting this for the past whole week but still can't find any solution. It's a strange problem.

I'm using bind 9.2.1 for my internal network LAN, and it's a Debian box. All the query for internal zone was working fine, but on last Wednesday, in a sudden, all the request to external site like yahoo.com or google.com doesn't give back a answer to the clients (mix of WinXP and linux box)

My named.conf.options initially was like this:

Code:

   
options {
        directory "/var/cache/bind";

        query-source address * port 53;
        auth-nxdomain no;    # conform to RFC1035

        forwarders {202.188.0.133;202.188.1.5;};
        forward only;
};

which 202.188.0.133 is my ISP dns ip.
Then I suspect it's my ISP dns problem, so comment out the 'forward only' and do a bind9 restart. For a few second it able to give answer back to the client, but just a while it start to timeout to client again.
Then I commented out the forwarders as well, and again, it works fine for a few seconds, then it fail again.
Then I found out my dns server actually did get back the answer, cause when I do a 'rndc flush' and 'dig @localhost yahoo.com', and then a 'rndc dumpdb', in the /var/cache/bind/named_dump.db, I did able to see this:

Code:

; glue
yahoo.com.		47701	NS	ns1.yahoo.com.
			47701	NS	ns2.yahoo.com.
			47701	NS	ns3.yahoo.com.
			47701	NS	ns4.yahoo.com.
			47701	NS	ns5.yahoo.com.
; glue
ns1.yahoo.com.		171154	A	66.218.71.63

Means, the bind9 server is not able to give answer back to anyone, including itself ! Which part is wrong ?

I really some expert out there could give me a hand, as my LAN Internet has down for a week already

( It's driving me nuts..

FMC · 06-18-2007, 08:06 AM

You can configure your ISP DNS server on the other machines for a while, this way people can work at least! lol

Flush all your iptables rules and try again, maybe you´re firewalling something!

Remember, when you do everything and have no clue about the problem, its time to strace and go crazy!

[]´s, FMC!

sloganyart · 06-19-2007, 01:54 AM

Quote:

Originally Posted by FMC

Flush all your iptables rules and try again, maybe you´re firewalling something!

How to flush iptables rules ? Which files or command to look into ?

FMC · 06-19-2007, 06:30 AM

iptables -F
iptables -t nat -F

This will flush your iptables rules, check iptables -L -n to see if the default policy is ACCEPT, if not just change it:
iptables -P INPUT ACCEPT

Take a look on iptables -t nat -L -n to know how your nat table is working.

[]´s, FMC!