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Old 10-30-2004, 07:21 AM   #1
krisprasad
LQ Newbie
 
Registered: Oct 2004
Posts: 3

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Not connecting to my DNS nameserver


Hi,

I am using an ISP connection (dialup modem) using wvdial with REDHAT 8
I am getting assigned IP address and my routing table looks fine.

But i am nt able to browse the Internet , since the DNS lookup is failing

I have the following two entries in my /etc/resolv.conf

nameserver 61.1.128.65
nameserver 61.1.128.5

I am able to ping these Server IPs. Also, i tried giving an IP address of
yahoo(i found this by dialing up from windows), and my yahoo first page came up.

So, i could figure out that the routing is fine , but somehow my DNS look up is failing

Then i tried the following 'strace route' When i do this, i found the
tcp connect (... ) not succeeding on both the nameserver ips mentioned above

I also tried telnet <ip> 53 ( assuming 53 is where DNS server listens to )

Again, I also tried giving the IP address of some Public Domain Nameserver
ie 199.166.29.3 ...etc , but no luck :-(

Is there anything i am missing.?

Can someone pls help me ?

Thanks in advance
Prasad

Note:
When i use the same dialup connection in Windows 98 and then using winipcfg command , i found that that the "above" DNS IP addresses are
present in DNS IP in "More info" tab
 
Old 10-30-2004, 07:34 AM   #2
scowles
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Registered: Sep 2004
Location: Texas, USA
Distribution: Fedora
Posts: 620

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Have you checked to see if your linux box is starting a firewall script of some kind that is blocking DNS requests? I don't remember what RH8 used, but its either ipchains -L or iptables -L.
 
Old 10-30-2004, 07:35 AM   #3
TigerOC
Senior Member
 
Registered: Jan 2003
Location: Devon, UK
Distribution: Debian Etc/kernel 2.6.18-4K7
Posts: 2,380

Rep: Reputation: 49
Make sure you do not have a gateway set on the connecting box because it will try to connect via a network card if you have one.
 
Old 10-30-2004, 08:18 AM   #4
krisprasad
LQ Newbie
 
Registered: Oct 2004
Posts: 3

Original Poster
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Hi ,

It is working now :-) am writing this browsing thru my linux box :-)

Thanks a lot to the reply esp. from scowles

I tried iptables -L . saw the following


[root@localhost root]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
RH-Lokkit-0-50-INPUT all -- anywhere anywhere

Chain FORWARD (policy ACCEPT)
target prot opt source destination

Chain OUTPUT (policy ACCEPT)
target prot opt source destination

Chain RH-Lokkit-0-50-INPUT (1 references)
target prot opt source destination
ACCEPT udp -- 61.1.128.5 anywhere udp spt:domain dpts:1025:65535
ACCEPT udp -- 61.1.128.65 anywhere udp spt:domain dpts:1025:65535
ACCEPT tcp -- anywhere anywhere tcp dpt:smtp flags:SYN,RST,ACK/SYN
ACCEPT tcp -- anywhere anywhere tcp dpt:http flags:SYN,RST,ACK/SYN
ACCEPT all -- anywhere anywhere
REJECT tcp -- anywhere anywhere tcp flags:SYN,RST,ACK/SYN reject-with icmp-port-unreachable
REJECT udp -- anywhere anywhere udp reject-with icmp-port-unreachable


I used lokkit and disabled the firewall and then I am able to reach DNS and am able to browse :-)

BTW, i have a question :: The firewall rules seem OK to me ,, ie it should accept UDP Packets
from the 61.1.128.5 and 61.1.128.65 . Still somehow the packets were nt accepted ( when the firewall rule
was present )

Any thing i am missing here?

Thanks a lot

Prasad
 
  


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