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Old 12-20-2014, 02:51 AM   #1
primorec
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Registered: Sep 2004
Distribution: RH5.2/6.2/8.0/9.0,RHEL 3.0/4.X/5.X/6.X,MDK 10.1,KNOPPIX3.6,Solaris 8/9,CentOS 3.X/4.X/5.X/6.X/7.X
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no access to certain WEB sites using CentOS 6


HW:
Lenovo T520 laptop with MS WIN 7
OR
dedicated PC (DELL GX 280)

SW:
CentOS 6.5 (64-bit) installed on VMware Player on MS WIN 7 host
CASE A) -- BRIDGED networking selected
CASE B) -- NAT networking
OR
CentOS 6.5 i(32-bit) nstalled on real HW (DELL OptiPlex GX 280)

___issue____ at hand:

The default Firefox ESR browser (17.0.10) does not find many web pages.
regardless of the system (virtual - bridged or NAT OR real HW)

For example:
https://www.google.com/ works
When I enter into search field string 'opera browser'
https://www.google.com/search?q=oper...ient=firefox-a

I do get a lot of results back. So far so good.

Then I click on the first searched link http://www.opera.com/
I get back

Server not found
Firefox can't find the server at www.opera.com

Then I open gnome-terminal and type
ping www.opera.com

I get back __nothing__

[igor@localhost ~]$ ping www.opera.com
PING www.route53.opera.com (54.244.236.138) 56(84) bytes of data.

but

when I type

ping opera.com

I get back

[igor@localhost ~]$ ping opera.com
PING opera.com (185.26.182.79) 56(84) bytes of data.
64 bytes from front-ams.opera.com (185.26.182.79): icmp_seq=1 ttl=41 time=174 ms
64 bytes from front-ams.opera.com (185.26.182.79): icmp_seq=2 ttl=41 time=122 ms

========================
another example
========================
http://www.delo.si/ works
http://www.dnevnik.si does __not__ work

http://www.centos.org/ works
but when I click on the link Special Interest Group on the same page
http://wiki.centos.org/SpecialInterestGroup , the link does NOT work.
I get back

Server not found
Firefox can't find the server at www.opera.com.

:::important:::
All the examples from above work flawlessly on the MS WIN 7 on the
same laptop, the same ETHERNET cable connected to the same switch hub
with the same router at the same time.
[Reminder: CentOS 6.5 runs on VMWare on WIN 7]


Any hint, FAQ, pointer to RTFM is more than welcome

I am puzzled, please help
 
Old 12-20-2014, 04:12 AM   #2
unSpawn
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Do the addresses work with any other web browser?
If they don't what does using 'curl -I [some_address];' on those addresses return?
 
Old 12-20-2014, 03:01 PM   #3
primorec
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I was able to remove firefox from the equation and reproduce the problem using curl

NON working URL


[igor@localhost ~]$ ping www.iquaid.org
PING www.iquaid.org (208.97.177.112) 56(84) bytes of data.
64 bytes from apache2-ogle.welchs.dreamhost.com (208.97.177.112): icmp_seq=1 ttl=40 time=44.4 ms
64 bytes from apache2-ogle.welchs.dreamhost.com (208.97.177.112): icmp_seq=2 ttl=40 time=44.9 ms
64 bytes from apache2-ogle.welchs.dreamhost.com (208.97.177.112): icmp_seq=3 ttl=40 time=44.9 ms
^C
--- www.iquaid.org ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2835ms
rtt min/avg/max/mdev = 44.475/44.791/44.976/0.332 ms

[igor@localhost ~]$ curl -I www.iquaid.org
curl: (6) Couldn't resolve host 'www.iquaid.org'

working URL

[igor@localhost ~]$ ping www.google.com
PING www.google.com (74.125.137.99) 56(84) bytes of data.
64 bytes from yh-in-f99.1e100.net (74.125.137.99): icmp_seq=1 ttl=40 time=24.0 ms
64 bytes from yh-in-f99.1e100.net (74.125.137.99): icmp_seq=2 ttl=40 time=24.4 ms
64 bytes from yh-in-f99.1e100.net (74.125.137.99): icmp_seq=3 ttl=40 time=24.1 ms
C64 bytes from yh-in-f99.1e100.net (74.125.137.99): icmp_seq=4 ttl=40 time=24.8 ms
^C
--- www.google.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2283ms
rtt min/avg/max/mdev = 23.797/23.977/24.169/0.234 ms

[igor@localhost ~]$ curl -I www.google.com
HTTP/1.1 200 OK
Date: Sat, 20 Dec 2014 18:28:27 GMT
Expires: -1
Cache-Control: private, max-age=0
Content-Type: text/html; charset=ISO-8859-1
Set-Cookie: PREF=ID=1bbec9638e094178:FF=0:TM=1419100107:LM=1419100107:S=gM_va5X8lh-0JQCB;
expires=Mon, 19-Dec-2016 18:28:27 GMT; path=/; domain=.google.com
Set-Cookie: NID=67=OCZyJIsZHlH417BzoIBG9H6qeb4G01ilsm_kzaIRa8rwQzd7w208O7j2cIvzchxEOSN9akek3qkO81kuVlnKzkXhzg85S eahbfbOkZUCZ8zB-iup8TOzG2dEkWIIjwi_;
expires=Sun, 21-Jun-2015 18:28:27 GMT; path=/; domain=.google.com; HttpOnly
P3P: CP="This is not a P3P policy! See
http://www.google.com/support/accoun...&answer=151657 for more info."
Server: gws
X-XSS-Protection: 1; mode=block
X-Frame-Options: SAMEORIGIN
Alternate-Protocol: 80:quic,p=0.02
Transfer-Encoding: chunked

nslookup and traceroute output

[igor@localhost ~]$ nslookup www.google.com
Server: 192.168.1.254
Address: 192.168.1.254#53

Non-authoritative answer:
Name: www.google.com
Address: 173.194.37.49
Name: www.google.com
Address: 173.194.37.52
Name: www.google.com
Address: 173.194.37.50
Name: www.google.com
Address: 173.194.37.51
Name: www.google.com
Address: 173.194.37.48

[igor@localhost ~]$ nslookup www.iquaid.org
Server: 192.168.1.254
Address: 192.168.1.254#53

Non-authoritative answer:
Name: www.iquaid.org
Address: 208.97.177.112

[igor@localhost ~]$ traceroute www.google.com
traceroute to www.google.com (74.125.196.106), 30 hops max, 60 byte packets
1 192.168.1.254 (192.168.1.254) 0.290 ms 0.311 ms 0.387 ms
2 adsl-98-70-114-1.tys.bellsouth.net (98.70.114.1) 7.702 ms 10.346 ms 12.766 ms
3 70.159.238.70 (70.159.238.70) 26.058 ms 28.418 ms 30.813 ms
4 70.159.238.69 (70.159.238.69) 31.993 ms 34.428 ms 37.330 ms
5 70.159.238.73 (70.159.238.73) 40.007 ms 42.435 ms 44.889 ms
6 70.159.238.85 (70.159.238.85) 46.044 ms 16.465 ms 18.511 ms
7 12.81.60.58 (12.81.60.58) 19.950 ms 14.904 ms 17.235 ms
8 12.81.60.70 (12.81.60.70) 22.624 ms 23.585 ms 27.477 ms
<snip> <snip> <snip>
20 209.85.243.254 (209.85.243.254) 44.328 ms 23.293 ms 209.85.248.31(209.85.248.31) 23.022 ms
21 * * *
22 yk-in-f106.1e100.net (74.125.196.106) 32.666 ms 34.817 ms 37.496 ms

[igor@localhost ~]$ traceroute www.iquaid.org
www.iquaid.org: No address associated with hostname
Cannot handle "host" cmdline arg `www.iquaid.org' on position 1 (argc 1)
 
Old 12-20-2014, 07:52 PM   #4
unSpawn
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I'm sorry but you didn't. We require "curl -I" output on an URI that doesn't work.
 
Old 12-20-2014, 08:25 PM   #5
veerain
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In CENTOS try editing the /etc/resolv.conf file and add

---------------------------
nameserver 8.8.4.4
nameserver 8.8.8.8
--------------------------

These are google public nameservers.

Most ISP's nameserevers block certain sites. But google doesn't.

Comment out other lines having nameserver with a # at start.
 
Old 12-21-2014, 10:13 AM   #6
primorec
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Quote:
Originally Posted by unSpawn View Post
I'm sorry but you didn't. We require "curl -I" output on an URI that doesn't work.
The 'I' is there

[igor@localhost ~]$ curl -I www.iquaid.org
curl: (6) Couldn't resolve host 'www.iquaid.org'
 
Old 12-21-2014, 10:16 AM   #7
primorec
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Registered: Sep 2004
Distribution: RH5.2/6.2/8.0/9.0,RHEL 3.0/4.X/5.X/6.X,MDK 10.1,KNOPPIX3.6,Solaris 8/9,CentOS 3.X/4.X/5.X/6.X/7.X
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Mystery resolved. The CAT5 cable from router to the switch hub was flaky. After I've replaced it with another one all the illogical puzzling behavior went away. What I do not understand is why, for example, some sites like, www.google.com and www.gmail.com worked flawlessly all the time. At same time some sites (like www.delo.si) worked and some others did not (like www.dnevnik.si).
 
Old 12-21-2014, 01:22 PM   #8
John VV
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just a guess but..

google and the google gmail have SO MANY!!! dns entries that it is nearly imposible to not find them
so for lesser known sites the host might not have been resolvable from the cache

but just a guess
 
Old 12-21-2014, 01:30 PM   #9
unSpawn
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Hmm, not a bad guess.
 
  


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