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Old 01-02-2012, 05:34 PM   #1
laskays
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blocking or unblocking users access to internet


Hi friends.
I am very new to linux and I was tasked to block access access to internet for certain users. The guy who did it initially did not leave an documentation and am really stuck. How do i go about and where exactly do I go to for me to start inputing the commands. I HAVE never used Centos 5 linux. 5 other computers have access to internet and they use dhcp and the rest are on static ip and they do not connect. When i put them on dhcp then cant still connect it i put them back on static ip with a gateway, they cant still access and i suppose there is An acl file i should play around with, please help.
 
Old 01-02-2012, 05:52 PM   #2
gilead
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Are your users accessing the Internet via a proxy or are some of them behind firewalls? You can check proxy settings in your browser (or your environment variables). Once you know how users are accessing the Internet then you can restrict it
 
Old 01-02-2012, 06:06 PM   #3
laskays
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No they are not using proxy
actually for setting internet, we i go to internet options we only tick automatically detect setting for those 5 I found using the net. I do not know how they are restricted now. so my worry is how do i allow access or deny access in centos 5

thanks steve, waiting to hear from you
 
Old 01-03-2012, 12:53 AM   #4
btmiller
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You did not answer if the users are behind a firewall. Is the CentOS 5 machine acting as a router and firewall between the network that the users are on and the Internet?

Can you tell if the settings IE is being set to detect automatically include proxy settings? Or, possibly, certain computers on the internal network just have all their Internet traffic blocked. Do you know if the users to be blocked always use the same computers?

A bit more information about how the network is set up would be helpful. If possible, I'd try to get in touch with the guy who set it up originally and see if he will just tell you how he did it.
 
Old 01-03-2012, 12:55 AM   #5
btmiller
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Another thought that cropped into my head is that traffic might be being blocked by MAC address. If you run "iptables -L" on the CentOS box, what do you see? This should help us determine if firewall rules are doing the blocking, or if something else is at work.
 
Old 01-03-2012, 01:15 AM   #6
laskays
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hey thanks for explaining more, When i get to work i will run "iptables -L"
The automatic setting does not include proxy, we leave it blank. The guys let the country and is nowhere to be found
perhaps I have to set anew the protocols in a new linux box. Its not the firewall rules from my on understanding, I thought on acl config u can set rules to deny certain users from connecting. Well I am a layman now, let me write you when i run iptables
 
  


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