Internet sites not working in FF browser / CentOS

mobilpress · Post by **mobilpress** » 2011/07/20 09:48:38

I need small help. I installed CentOS. NetworkManager successfully installed and launched. I can ping any IP from terminal but I can't open any site in browser except 127.0.0.1 I can't open IP of the modem 192.168.1.1 in browser also.

The results of some commands:

[b]ifconfig[/b]
eth0 Link encap: Ethernet HWaddr 7D:60:00:00:00:00
inet addr: 192.168.1.5 Bcast: 192.168.1.255 Mask:255.255.255.0
inet6 addr: fe80::7f60:ff:fe00:0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:58 errors:0 dropped:0 overruns:0 frame:0
TX packets:49 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3640 (3.5 KiB) TX bytes:8862 (8.6 KiB)
Interrupt:50 Base address:0xdead

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1572 errors:0 dropped:0 overruns:0 frame:0
TX packets:1572 errors:0 dropped:0 overruns:0 carrier:0

====================
[b]nslookup google.com[/b]
connection timed out; no servers could be reached
====================
[b]ping google.com[/b]
ping: unknown host google.com
====================
[b]curl -l google.com[/b]
curl: (6) Couldn't resolve host 'google.com'

Any ideas?

Post by **TrevorH** » 2011/07/20 13:05:08

I found at least one hit on google that says that a SIS network card with that weird "0xdead" memory address cannot handle an MTU of 1500 and it needs to be set to 1436 or less. That article recommended 1024.

foxb · Post by **foxb** » 2011/07/20 14:34:41

Nameservers?

cat /etc/resolv.conf

mobilpress · Post by **mobilpress** » 2011/07/20 16:30:15

I wrote DNS1 and DNS2 in /etc/sysconfig/network-scripts/ifcfg-eth0 which I received from Internet provider:
DNS1=82.209.253.4
DNS2=193.232.248.2

Now:
[b]cat /etc/resolv.conf[/b]
nameserver 82.209.253.4
nameserver 193.232.248.2

[b]ping google.com[/b]
OK 0%packet loss etc.

[b]nslookup google.com[/b]
Server: 82.209.253.4
Address: 82.209.253.4#53

Non-authoritative answer:
Name: google.com
Address: 74.125.39.103
etc.....................................

[b]curl -l google.com[/b]

No any answer :-(

And the browsing from Firefox not working as before.

Post by **TrevorH** » 2011/07/20 21:09:43

So you can ping and use nslookup both of which use small packets that probably don't use the entire 1500 byte MTU that you had set before. Did you try reducing the MTU to a smaller value? Try `ifconfig eth0 mtu 1024` and see if that helps. If it works then try halfway between 1024 and 1500 and keep trying halfway values until you narrow it down to a workable value that's as big as it can be.

mobilpress · Post by **mobilpress** » 2011/07/20 21:49:03

Tested to change MTU.

No success.

Post by **TrevorH** » 2011/07/20 22:43:25

Post the output from the getinfo.sh script that can be found in the [url=http://www.centos.org/modules/newbb/viewtopic.php?topic_id=25128&forum=47]FAQ section[/url] of this forum

[Moderator edit: Add link for the convenience of the OP. :-) ]

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