Re: DNS problem

On Thu, 14 Oct 2010 11:44:25 -0700, sl@exabyte wrote:

> I have a related problem.

Next time open your own thread.

> On my web server, there are several domains. However, some domains can be
> "ping", some cannot.

If can be pinged by ip but not name, DNS issue.

If not by ip, blocked by software (firewall, blacklist,....) .

> DNS virus ?

Only if criminals have installed their malware DNS server.

> One of them cannot be "ping" but can be reached via FTP. ????

If can be pinged by ip but not name, DNS issue. If not by ip, blocked
by software (firewall, blacklist,....) .

On Wed, 13 Oct 2010 22:30:09 -0700 (PDT), Pan wrote:
> My issue is worse because I can't visit Internet with firefox on the
> Linux.

Open your own thread instead of trying to high-jack this thread.

Click up a terminal
ping -c 1 209.191.122.70 if works, do a
ping -c 1 www.yahoo.com if works, then

firefox www.yahoo.com should work.

>> On my web server, there are several domains. However, some domains can be
>> "ping", some cannot.
>
> If can be pinged by ip but not name, DNS issue.
>
> If not by ip, blocked by software (firewall, blacklist,....) .
>

I can ping with IP, not name. An hour ago cannot ping, now OK.

Never alter firewall.

>> DNS virus ?
>
> Only if criminals have installed their malware DNS server.
>

What I mean is virus on my PC. Possible ? Thanks

>> One of them cannot be "ping" but can be reached via FTP. ????
>
> If can be pinged by ip but not name, DNS issue. If not by ip, blocked
> by software (firewall, blacklist,....) .

>
>> I have a related problem.
>
> Next time open your own thread.
>
>> On my web server, there are several domains. However, some domains can be
>> "ping", some cannot.
>
> If can be pinged by ip but not name, DNS issue.
>
> If not by ip, blocked by software (firewall, blacklist,....) .
>

I have 2 PCs on my table (connected to a desktop switch), one pc can "ping",
but the other cannot "ping" (the same domain).

On Thu, 14 Oct 2010 14:06:11 +0800, sl@exabyte wrote:

> I can ping with IP, not name. An hour ago cannot ping, now OK.

That sounds like system admin updating system.

> What I mean is virus on my PC. Possible ? Thanks


Since you are posting from a Micro$oft OS, entirely possible.
Intermittent, maybe just a poisoned DNS cache.

On Thu, 14 Oct 2010 14:10:21 +0800, sl@exabyte wrote:

> I have 2 PCs on my table (connected to a desktop switch), one pc can "ping",
> but the other cannot "ping" (the same domain).

One more time,
if broke PC can not ping by ip, software problem (firewall, routing,..).

If can not ping by name, DNS problem.

On Wed, 13 Oct 2010 23:28:07 -0700 (PDT), Pan wrote:

> I'm the author of the first post for this thread, I'm saying the same
> problem of my network issue.

Sorry about that, original post was indicating you could not ping a
node but indicated connectivity. Your firefox post indicated something
entirely different was broke and I did not remember your name from the
initial post.

I would reboot your network and see if you can
ping -c 1 72.30.2.43 if that works, you know you have connectivity.

so, click up a terminal
sudo -i

restart network-manager
ping -c 1 72.30.2.43

If that works,
ping -c 1 yahoo.com

Tell us what happens.

On Thu, 14 Oct 2010 00:58:50 -0700 (PDT), Pan wrote:
> On Oct 14, 2:41Â*pm, Bit Twister <BitTwis...@mouse-potato.com> wrote:
>
>> I would reboot your network and see if you can
>> ping -c 1 72.30.2.43 Â* Â* Â*if that works, you know you have connectivity.
>>
>> so, click up a terminal
>> sudo -i
>>
>> restart network-manager
>> ping -c 1 72.30.2.43
>>
>> If that works,
>> ping -c 1 yahoo.com
>>
>> Tell us what happens.
>
> all above pings work fine, so the problem is non-root user can't ping
> a host-name, how to fix it?

Hmmm, I want to see actual commands and results from the user's terminal.

> The ping to a host name gave me the "unknown host" error, however at
> the same time, the "apt-get update" can still connect the remote
> official host, I don't work behind a firewall or block any outside
> ICMP traffic, so this is wired, does anyone know what's issue with my
> network?

I have a related problem.

On my web server, there are several domains. However, some domains can be
"ping", some cannot. DNS virus ?

One of them cannot be "ping" but can be reached via FTP. ????

Thanks.

On Thursday 14 October 2010 09:58 in comp.os.linux.networking, somebody
identifying as Pan wrote...

> On Oct 14, 2:41Â*pm, Bit Twister <BitTwis...@mouse-potato.com> wrote:
>
>> I would reboot your network and see if you can
>> ping -c 1 72.30.2.43 Â* Â* Â*if that works, you know you have
>> connectivity.
>>
>> so, click up a terminal
>> sudo -i
>>
>> restart network-manager
>> ping -c 1 72.30.2.43
>>
>> If that works,
>> ping -c 1 yahoo.com
>>
>> Tell us what happens.
>
> all above pings work fine, so the problem is non-root user can't ping
> a host-name, how to fix it?

Your distribution probably doesn't have "/bin/ping" set up as SUID root,
which means that a regular user won't be able to use it successfully
because a ping is a privileged operation. If you do need for an
unprivileged user to be able to ping, issue the following command as
root in a terminal window...

chmod +s /bin/ping

--
*Aragorn*
(registered GNU/Linux user #223157)