| manuel220 |
08-17-2011 09:31 PM |
What can be blocking the DNS response going back to my server?
1 Attachment(s)
I have a server with a hosting company, but not sure where but it started failing on every DNS request.
I stopped iptables, I see that I can get response from the DNS when using tcp but not udp. What else can be blocking the response from DNS on default udp??
I've requested network team of the hoster to allow udp to my server from the specific DNS server's ip.
Code:
cat /etc/resolv.conf
nameserver 8.8.8.8
nameserver 66.96.80.194
nameserver 66.96.80.43
Code:
[root@armadaazteca ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
Code:
[root@armadaazteca ~]# route -n
Kernel IP routing table
Destination Gateway Genmask Flags Metric Ref Use Iface
68.233.243.0 0.0.0.0 255.255.255.0 U 0 0 0 eth0
169.254.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth0
0.0.0.0 68.233.243.1 0.0.0.0 UG 0 0 0 eth0
dig default using udp
Code:
[root@armadaazteca ~]# dig www.yahoo.com
; <<>> DiG 9.3.6-P1-RedHat-9.3.6-16.P1.el5 <<>> www.yahoo.com
;; global options: printcmd
;; connection timed out; no servers could be reached
dig using tcp
Code:
[root@armadaazteca ~]# dig +tcp www.yahoo.com
; <<>> DiG 9.3.6-P1-RedHat-9.3.6-16.P1.el5 <<>> +tcp www.yahoo.com
;; global options: printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 63578
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;www.yahoo.com. IN A
;; ANSWER SECTION:
www.yahoo.com. 258 IN CNAME fp3.wg1.b.yahoo.com.
fp3.wg1.b.yahoo.com. 19 IN CNAME any-fp3-lfb.wa1.b.yahoo.com.
any-fp3-lfb.wa1.b.yahoo.com. 259 IN CNAME any-fp3-real.wa1.b.yahoo.com.
any-fp3-real.wa1.b.yahoo.com. 19 IN A 209.191.122.70
;; Query time: 34 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Wed Aug 17 21:26:04 2011
;; MSG SIZE rcvd: 128
finaly a small packet capture
Attachment 7818 |
