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CentOS network issue

Posted on 2011-03-21
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Last Modified: 2012-06-21
Hi,

My centOS 5.5 server can ping the wireless router but not the laptops in the intranet. The laptops however can ping the server. All laptop and centOS server are assigned IP automatically.

Please help.

Thanks
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Question by:wsyy
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12 Comments
 
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Expert Comment

by:upanwar
ID: 35187367
Which OS you are using in your laptops. If its Linux then stop the firewall by issuing below given command.

# iptables --flush

and try to ping your laptop.

If you are using the WIndows XP then disable the firewall from your network connection properties.

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Expert Comment

by:pilson66
ID: 35188872
In yout wireless router, you need to disable feature named like "Set AP isolated".
This feature prevents wireless clients communicate with each other.

Or, if you setup wireless router as "router", and connect intranet segment to WAN port  - you need to set router to "AP" (not routing) mode and connect intranet segment to one of LAN ports in riouter.

P.S. Sorry for my English.
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Expert Comment

by:pilson66
ID: 35189267
Also, in wireless routeryou need to disable DHCP server, to prevent conflicts with DHCP server in intranet segment.
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Author Comment

by:wsyy
ID: 35190612
upanwar:

My laptops are using Windows 7. Do you think that is the reason?
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Author Comment

by:wsyy
ID: 35190717
pilson66:

The network topology is this:

1. An adsl modem connected through PPoE to internet (outside network);
2. A wireless router connected to the modem;
3. A centOS server directly connected to one of the router's port;
4. A few laptops and desktops of Windows 7 OS connected to the router wirelessly.

I don't think I have firewall set up explicitly unless Windows 7 automatically does.

Also, I don't know why I have to stop DHCP internally since the laptops and desktops work fine, and the server can get internet as well. The only issue is that the CentOS server can't connect to the laptops and desktops while the laptops and desktops can ping it.

Thanks
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Expert Comment

by:upanwar
ID: 35190763
Disable the firewall on one of your desktop or laptop and test. It should work.
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LVL 8

Expert Comment

by:pilson66
ID: 35190842
Laptops connected through Wi-Fi? If yes - you need to disable feature named like "Set AP isolated".
This feature prevents wireless clients communicate with each other.
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Expert Comment

by:pilson66
ID: 35190866
Also
on CentOS: show "ifconfig" and "iptables-save"
on laptops: show "ipconfig /all"
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Author Comment

by:wsyy
ID: 35191743
upanwar:

I just notice that the laptops have Windows Firewall on. Is this what you mean?
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Author Comment

by:wsyy
ID: 35191771
I will check the solutions you guys recommended.

Please take a look at this post and help!

http://www.experts-exchange.com/OS/Unix/Q_26903551.html
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Accepted Solution

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upanwar earned 250 total points
ID: 35191803
Yes, just disable that and check.
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Author Closing Comment

by:wsyy
ID: 35195113
Thanks great help!
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