Hi Guys - some comments ...
The only effective way of "policing" internet traffic is to force all of the
traffic through some form of filter - if you have a router (at your end of
your internet connection) with its own Firewall which has the ability to
filter traffic, then that should probably be sufficient - but make sure that
you really do understand what it is doing and what it doesn't do.
Otherwise, you must either filter on each client (ie. via a driver) OR by
interposing another box in the network path.
The advantage of using another box (ie. not a driver) is that it will
enforce the "rules" regardless of what browser (or what operating system)
the clients use. It can also apply rules to other traffic (ie non-HTTP).
ie Internet_Link -- Modem/Router -- Filter_Box -- Clients
This way, no matter what a client does, the network traffic must flow
through the filter (and therefore be subject to the "rules")
The Filter_Box would need to support the standard network protocols (http,
https, ftp, NTP, DNS, SMTP, POP3, etc) and to be really useful it would also
provide DHCP and Proxy services.
Most firewall products do this (and more) and some proxy servers do a pretty
good job as well
(ASIDE: I have used free Linux based software for this on a very old PC -
the overhead for the filtering is not high
Also, as the rulebase on my Internet router at home did not cover all things
I needed, I have "FreeProxy" running on an XP box (its rulebase is quite
extensive. I have a rule the router that only allows that computer to access
the internet)
Could the "filter" be written in Delphi = "of course"
{On the client side, it would need to have a "Server" for each port (both
TCP & UDP) to be filtered AND on the Internet side it needs to be a client
acting on the same ports - for ports not coded, it would not pass the
traffic
Then it would need to present an interface for Rule management and,
obviously, an engine which applies the rules to traffic passing through.
This is addition to implementing full support for each of the protocols
}
While such a task would be great as a programming exercise, in a practical
sense, starting from scratch would be a huge undertaking. You would have to
understand/learn all of the nuances of each protocol you would like to
support. (NB : Microsoft do NOT fully implement some protocols & have
others as variants - if your clients are MS-Windows based, you will need to
support their variations as well)
If your aim is to protect your children - look at your Internet Router And
its available rule set and also consider using something like "FreeProxy".
If your aim is to generate income from
(a) a Filtering product, then consider reviewing what "Squid", "Smoothie" &
FreeProxy" do.
(b) a "Driver" application which would sit on each PC, then Delphi cannot
be used. It cannot generate "drivers".
Regards,
Brian
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
On Behalf Of Cosmin Prund
Sent: Tuesday, August 29, 2006 12:10 AM
To: Delphi-Talk Discussion List
Subject: Re: Block a website in IE using delphi program
Next the kid will download Opera. Opera has a really nice easy setting
for "proxy". Just hit F12 and you'll get a popup allowing you to
enable/disable proxy servers with a single click. Proxy settings are
"voluntary" in a way. The application doing the actual connecting to the
Internet has to actually WANT to use the proxy and KNOW HOW to use the
proxy. Most 3rd party browser don't care about Internet Explorer's
global Internet Connection Settings!
The bottom line is this: a "normal" proxy server can't be trusted for
any kind of "parental control". You'll need to use some sort of
"transparent proxy" (where ALL http traffic is intercepted, no matter
how that traffic is generated). An "transparent proxy" would block
requests to prohibited sites from ANY browser, including Internet
Explorer, Firefox or Opera.
The required functionality for providing effective parental control lies
somewhere between a firewall and a proxy, with the "firewall" part being
more important.
If this is for "home use" the cheeper way might be installing a Linux
box with squid or some other open-source transparent proxy.
If this is for "production use" Delphi might not be the best tool for
the job, mainly because it can't be used to write "drivers" and
implementing the firewall bit required for intercepting all HTTP traffic
requires writing some kind of driver.
[EMAIL PROTECTED] wrote:
> So basically, the kid uses firefox and gets all the porn he wants. You may
> look to the indy components to create a proxy server instead. Those
settings
> can be made system wide.
>
> On 8/25/06, Kraven -
>
[EMAIL PROTECTED]<+delphitalk+coreyw+0a392a17b8.kraven#greycascade.com@
> spamgourmet.com> wrote:
>
>> Hi guys,
>> I want to build a website parental control program which block sites from
>> Internet Explorer.
>>
>> There are two things I need to know:
>>
>> 1) How to get all URL's entered in Internet Explorer
>> 2) How to force that specific instance of Internet Explorer to navigate
to
>> another page.
>>
>> Can anyone help?
>>
>> Thanks in advance,
>> Simon
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