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Trick: Hijacking DNS as a Cheap Content Filter |
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Saturday, 29 September 2007 |
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Restricting
access to specific Internet web services is a challenge shared by all
network administrators. Whether the reason for restricting access is
based on security, bandwidth, or productivity, installing and
maintaining proxy and content filter applications may be outside the
budget of a small IT department. The solution provided here offers a cumbersome approach for a small investment: $0.
All web
services, such as HTTP, FTP, IRC, IM, NNTP and SMTP are predominantly
called by name when end users want to access them. An internal DNS
server usually hosts records for only the internal namespace. All
external (Internet) namespace is generally forwarded to an ISP’s or
other DNS server.
DNS hijacking on the LAN allows an
administrator to redirect all Internet requests for a domain or server
to an internal server or to nowhere (127.0.0.1). Read more at NewOrder.box.sk
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