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List:       ipcop-user
Subject:    Re: [IPCop-user] A question (blocking with a hosts file)
From:       "Renaud (Ron) Olgiati" <renaud () olgiati-in-paraguay ! org>
Date:       2013-03-15 9:20:13
Message-ID: 201303150620.14142.renaud () olgiati-in-paraguay ! org
[Download RAW message or body]

I wrote some years ago a how-to block sites with a /etc/hosts file.

As there seems to be interest I am posting it again.
 =

Cheers,
 =

Ron.
-- =

                          Ars imitatio naturae est.
                           -- Lucius Annaeus Seneca
                                    =

                   -- http://www.olgiati-in-paraguay.org --
 =



Stopping pop-up adds on a LAN with an extended hosts file on the IPCop =

firewall

	Why block popups ?

Because pop-ups not only waste your bandwidth, increase the load-up time of =

web-pages and generate annoyance, but many of them (starting with doublecli=
ck) =

track your web usage, and endanger your privacy.

	How can I block pop-ups ?

The easiest way is to use an extended /etc/hosts file, which redirect to IP =

127.0.0.1 all the known pop-up web sites.

On a LAN protected by an IPCop firewall, instead of  hacking the hosts file=
 of =

all the boxes on the LAN, you can do it on the IPCop box only, if the IPCop =

box is used as the primary DNS of the LAN.

Upside: only one hosts file to keep up to date.

Downside: more memory used on the IPCop box, a very slight increase in the =

response time for every DNS query. =

Note that web browsers will display some sort of "Unable to connect" warnin=
gs =

whenever a pop-up cannot be foud.

	Procedure, for IPCop 1.4.21

- Make up your badhosts files (127.0.0.1 doubleclick.com etc) or download a =

ready-made one from the net.
You can find the one I use at http://www.olgiati-in-paraguay.org/badhosts .

- Copy it via scp to the IPCop box : scp -P 222 badhosts =

root@(ipcopboxname):/var/tmp/

- One problem we have with IPCop is that the /etc/hosts file it uses is =

generated anew from the data in /var/ipcop/main/hosts each time the hosts.c=
gi =

script is run from the GUI.
So we must find a way to append our list of bad hosts to /etc/hosts each ti=
me =

hosts.cgi is run; to this end the obvious way would be to modify hosts.cgi =

itself, but moddifying the perl script is a bit complicated; so here is a =

quick and dirty workaround:

- Create on the IPCop box a file /usr/bin/addbadhosts with the content::
(beware of wrapped lines below)

#!/bin/bash
# Append my blacklist of hosts from /var/tmp/badhosts to /etc/hosts if =

hosts.cgi
# has been run to update /var/ipcop/main/hosts.
#R.Olgiati, with thanks to Kevin W. Wall

if [[ ! /var/ipcop/main/hosts -ot /etc/hosts ]]
then
        cat /var/tmp/badhosts >> /etc/hosts
        /bin/killall -s HUP dnsmasq
fi

Then run fcrontab -e and add the following two lines to crontab:
# Added for /etc/hosts append of badhosts
*/10 * * * *   /usr/bin/addbadhosts

which will ensure that even if you forget to run addbadhosts after modifyin=
g =

the hosts file through the GUI, the badhosts will be added to it within ten =

minutes.

Before you exit ssh you can also check your new host file with:

	grep doubleclick /etc/hosts

The  response time of the grep should reassure you concerning the possible =

delay in DNS queries.

=A9 Renaud Olgiati 2009; =

distributed under the Attribution-NonCommercial-NoDerivs 3.0 Unported Creat=
ive =

Commons Licence.   renaud@olgiatipy.org


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