name resolution problem?? Please help

complus · 03-01-2004, 09:04 AM

Hi - thanks for checking out the post. Any help is extremely appreciated since I'm in an urgent situation to get this working...

I believe I am having some name resolution issues. I have my name server in /etc/resolv.conf . I can ping the IP address from my server, so I know I can see it... but when I try to resolve any names my server just hangs.

I can resolve names that are in my /etc/hosts file. Other than that - nothing. For example, when I try to ping www.yahoo.com it just hangs. Here is the output from ifconfig:

Code:

eth0      Link encap:Ethernet  HWaddr 00:06:5B:8E:18: D7  
          inet addr:10.10.10.217  Bcast:10.10.10.255  Mask:255.255.255.0
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:1051 errors:0 dropped:0 overruns:0 frame:0
          TX packets:964 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:100 
          RX bytes:110161 (107.5 Kb)  TX bytes:372620 (363.8 Kb)
          Interrupt:5 Base address:0xdce0 Memory:feb60000-feb80000 

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:0 errors:0 dropped:0 overruns:0 frame:0
          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

And the output of route:

Code:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
10.10.10.0      *               255.255.255.0   U     0      0        0 eth0
127.0.0.0       *               255.0.0.0       U     0      0        0 lo
default         10.10.10.1      0.0.0.0         UG    0      0        0 eth0

Very strange though - it hangs after the 127.0.0.0 route and the default doesn't come up for a good 5 seconds or so... I know I've run into this a while ago but can't remember why that is...

Thanks in advance...

peter_robb · 03-01-2004, 09:24 AM

try dig -x 216.109.117.109 to check your nameserver from resolv.conf

or dig -x 216.109.117.109 @x.x.x.x to check nameserver x.x.x.x directly..

complus · 03-01-2004, 09:27 AM

peter - thanks for responding so quickly!

in either case (with and without specifying my DNS) the response I get is:
; <<>> DiG 9.2.1 <<>> -x 216.109.117.109
;; global options: printcmd
;; connection timed out; no servers could be reached

I'm still thinking name resolution problem... but I could be wrong since I am a newbie even though I've been trying to learn Linux for almost a year now

peter_robb · 03-01-2004, 09:30 AM

looks like the connection is being blocked...

Turn off your firewall and try again...

complus · 03-01-2004, 09:33 AM

Quote:

Turn off your firewall and try again... [/B]

Unfortunately turning off my firewall is not an option... This is an external firewall. I know I have IPTABLES installed on my server, but I have not configure it yet (plan on it as a secondary line of defense but only after I get this working properly). How do I make sure IPTABLES is not running? Here is the output of my ps -ef:

Code:

UID        PID  PPID  C STIME TTY          TIME CMD
root         1     0  0 09:46 ?        00:00:03 init
root         2     1  0 09:46 ?        00:00:00 [keventd]
root         3     1  0 09:46 ?        00:00:00 [ksoftirqd_CPU0]
root         8     1  0 09:46 ?        00:00:00 [bdflush]
root         4     1  0 09:46 ?        00:00:00 [kswapd]
root         5     1  0 09:46 ?        00:00:00 [kscand/DMA]
root         6     1  0 09:46 ?        00:00:00 [kscand/Normal]
root         7     1  0 09:46 ?        00:00:00 [kscand/HighMem]
root         9     1  0 09:46 ?        00:00:00 [kupdated]
root        10     1  0 09:46 ?        00:00:00 [mdrecoveryd]
root        16     1  0 09:46 ?        00:00:00 [scsi_eh_0]
root        17     1  0 09:46 ?        00:00:00 [scsi_eh_1]
root        20     1  0 09:46 ?        00:00:00 [kjournald]
root        78     1  0 09:46 ?        00:00:00 [khubd]
root       183     1  0 09:46 ?        00:00:00 [kjournald]
root       184     1  0 09:46 ?        00:00:00 [kjournald]
root       185     1  0 09:46 ?        00:00:00 [kjournald]
root       186     1  0 09:46 ?        00:00:00 [kjournald]
root       187     1  0 09:46 ?        00:00:00 [kjournald]
root       188     1  0 09:46 ?        00:00:00 [kjournald]
root       448     1  0 09:46 ?        00:00:00 syslogd -m 0
root       452     1  0 09:46 ?        00:00:00 klogd -x
root       535     1  0 09:46 ?        00:00:00 /usr/sbin/sshd
root       548     1  0 09:46 ?        00:00:00 gpm -t imps2 -m /dev/mouse
root       557     1  0 09:46 ?        00:00:00 crond
root       565     1  0 09:46 tty1     00:00:00 /sbin/mingetty tty1
root       566     1  0 09:46 tty2     00:00:00 /sbin/mingetty tty2
root       567     1  0 09:46 tty3     00:00:00 /sbin/mingetty tty3
root       568     1  0 09:46 tty4     00:00:00 /sbin/mingetty tty4
root       569     1  0 09:46 tty5     00:00:00 /sbin/mingetty tty5
root       570     1  0 09:46 tty6     00:00:00 /sbin/mingetty tty6
root       571   535  0 09:47 ?        00:00:00 /usr/sbin/sshd
root       573   571  0 09:47 pts/0    00:00:00 -bash
root       722   573  0 10:31 pts/0    00:00:00 ps -ef

Thanks.

complus · 03-01-2004, 09:38 AM

Actually - sorry - I didn't even realize that iptables was listed as one of the services to start on boot. I disabled it and rebooted. But I still get the same results.

The config of my external firewall has not changed and it was working previously, so I don't think the external firewall is the problem. It seems that someone on my server itself is the culprit....

peter_robb · 03-01-2004, 10:04 AM

do iptables-save to print your current rules on the screen...

If any are listed, do /etc/init.d/iptables stop and see if they clear.

If it's not you blocking them, then you have to look further out...

complus · 03-01-2004, 10:56 AM

Well - it was in fact the external firewall. I compared configs from now and before this all happened.. and there was a freaking typo!! A hyphen was used instead of an underscore....

Thanks so much for your help peter

peter_robb · 03-01-2004, 11:00 AM