Blocking Internet Access

Posted on 2001-09-03
Last Modified: 2010-03-17
In my classroom of 35 win98 computers and 1 linux server (Apache & Samba), there are certain times of the day that I prohibit Internet access only on the win98 computers. But I have to do it manually. I go to the hub and remove the coax cable that brings Internet access to my room. Is it possible to use linux to prevent my students from access the Internet at certain times?
Question by:lynn402

Expert Comment

ID: 6450931

You can do this using the access-control list capability of the squid proxy server. See and the squid home page at .



Expert Comment

ID: 6452020

Is linux acting as a router or is it also being used as a proxy server using SQUID?  if it is being used as as a proxy server you can do that as ifincham said through ACL in squid.  

If you need help on how to do it just let me know.

Also let me know if you are using it as a router only and whether you are using any firewalls or masquradig solutions.

Good Luck,


Expert Comment

ID: 6494929
I Asume that the linux box is used as internet gateway.

Then you could make scripts to change the filewall rules allowing or blocking internet connection to the internal lan. and execute them via cron at specific times.

Depending on the linux kernel and firewall rule demands, how the scripts sould be written.

Author Comment

ID: 6515252
No. I'm not using linux as a gateway. I'm using samba only.
Do I need to make it a gateway to block Internet access at certain times?
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Expert Comment

ID: 6518217
You could, a gateway is a device that connects two or more networks. So you'll have to create two seperate networks.

But I would like some more information before I can give you some usefull advise.

Is there a proxy or nat server in the schools network?
Are the IP addresses static or set by DHCP?
Are you usinging mutiple network ranges?


Expert Comment

ID: 6518263
Or even more easy.....

Buy a very old BNC-only hub and a (digital) wallsocket-timer.  


Author Comment

ID: 6534498
The addresses are dynamic.
I made a mistake in saying the "school's network".  The network is run by the school system. Therefore, other schools in the system are on the network, too.
There is a proxy.
I don't know if multiple net ranges are used.
How much does a old BNC hub cost? What features would it give me in controlling my classroom computers?

Accepted Solution

soulmate022700 earned 100 total points
ID: 6534650
An old BNC hub souldn't cost more than 15$. ( And in holland very hard to find, because now a days every body wants at least)
With a seccond hub you can preserve the lan connection within the classroom and be disconnected from the schools network. Just like unplugging the coax cable from hub, like you used to do. With a simple timer (mostly used for lamps) you can switch on and off the hub witch is connected to the schools LAN on specific times.
It's a very easy sollution.

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