Re: [Full-Disclosure] Proxies

[Ben Nelson]

Blocking all internal->external traffic and then allowing ONLY the 
needed services from the necessary hosts is the best way to stop this 
sort of abuse.  Then, using a web proxy that filters web content and 
only understands HTTP (to prevent other services from being tunneled 
over port 80), you should be good to go.

--Ben

Earl Keyser wrote:
Help needed, please.

We use all cisco networking gear. Currently using a cisco cache engine
with SmartFilter to "manage" the surfing for our staff/students.  As
usual, the little devils figured a way to get around it. 

They went to Google, entered "open proxy list" and bingo-bango.  From
this list they found open proxies to use in IE.
Besides suspending them, we made one technological change. Outgoing
ports 8000, 8080, 8888 and 3128 are now blocked at the firewall.
Can anyone suggest further refinements to reduce this kind of abuse? I
know some proxies run on port 80, but I'll have to live with that.
TIA

Earl

Earl Keyser, Network Specialist
Wayzata Public Schools
763-745-5105
"Unix IS user-friendly. It's just picky about who its friends are."

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.netsys.com/full-disclosure-charter.html