Question

Block sites using iptables, but not for certain users.

Asked by: enrique_salazar

I have been told to block certain site (facebook) using Iptables. I did this succesfully. Now I want to let certain users to the site (my boss, who asked me to block the site lol).

I put this, I thought putting a rule to let her IPs before the blocking rule would work, but it doesnt...

$IPTABLES -A FORWARD -s 10.6.2.237/32 -d 0.0.0.0/0 -j ACCEPT #user
$IPTABLES -A FORWARD -s 10.6.3.3/32 -d 0.0.0.0/0 -j ACCEPT #user
$IPTABLES -A FORWARD -s 10.6.2.250/32 -d 0.0.0.0/0 -j ACCEPT #user

$IPTABLES -t nat -A PREROUTING -p tcp -s 10.0.0.0/8 -d 69.63.176.0/24 -j DROP #facebook block

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Asked On
2008-04-15 at 08:52:11ID23324122
Tags

facebook

,

iptables

Topics

IP Tables/IP Chains

,

Network Software Firewalls

,

Linux

Participating Experts
1
Points
500
Comments
10

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Answers

 

by: ravenplPosted on 2008-04-15 at 09:07:52ID: 21359949

it hasn't worked because packet flies through PREROUTING chain, then FORWARD. So whole 10/8 gets blocked by PREROUTING

I think You should not use the PREROUTING chain here at all, just

$IPTABLES -A FORWARD -s 10.6.2.237/32 -d 0.0.0.0/0 -j ACCEPT #user
$IPTABLES -A FORWARD -s 10.6.3.3/32 -d 0.0.0.0/0 -j ACCEPT #user
$IPTABLES -A FORWARD -s 10.6.2.250/32 -d 0.0.0.0/0 -j ACCEPT #user
$IPTABLES -A FORWARD -s 10.0.0.0/8 -d 69.63.176.0/24 -j DROP #facebook block

 

by: enrique_salazarPosted on 2008-04-15 at 09:18:30ID: 21360045

It didnt work... now everyone has facebook again... any clue?

 

by: ravenplPosted on 2008-04-15 at 09:24:18ID: 21360112

where is the facebook? On the same host You configuring iptables?
If so, then change all "-A FORWARD" to "-A INPUT"
And don't forget to flush old entires.

 

by: enrique_salazarPosted on 2008-04-15 at 09:27:14ID: 21360139

uh? www.facebook.com, is a social-networking web site.

yes, I run ./rc.iptables everytime I change something

 

by: ravenplPosted on 2008-04-15 at 09:57:47ID: 21360441

> uh? www.facebook.com, is a social-networking web site.
My question was: is it hosted on same box as the iptables are run?

> yes, I run ./rc.iptables everytime I change something
I hope it flushes the iptables

 

by: enrique_salazarPosted on 2008-04-15 at 10:30:46ID: 21360745

well, www.facebook.com is a third party website i want block my users from accesing to. Of course, is not in the same box, not even in the same network.

Well, I did /etc/init.d/iptables stop and flushed all the firewall rules with no success.

 

by: ravenplPosted on 2008-04-15 at 10:45:46ID: 21360893

OK, so You are applying those rules on firewall - good. It should work with the FORWARD chain.

stop/start the firewall(so it's flushed and without Your rules), then apply those rules

$IPTABLES -N FACEBOOK
$IPTABLES -A FACEBOOK -s 10.6.2.237/32 -j ACCEPT #user
$IPTABLES -A FACEBOOK -s 10.6.3.3/32 -j ACCEPT #user
$IPTABLES -A FACEBOOK -s 10.6.2.250/32 -j ACCEPT #user
$IPTABLES -A FACEBOOK -s 10.0.0.0/8 -j DROP #facebook block

$IPTABLES -I OUTPUT -d 69.63.176.0/24 -j FACEBOOK
$IPTABLES -I FORWARD -d 69.63.176.0/24 -j FACEBOOK
#where 69.63.176.0/24 is the facebook IP/location

 

by: enrique_salazarPosted on 2008-04-15 at 13:20:35ID: 21362455

doesnt work :(

 

by: enrique_salazarPosted on 2008-04-15 at 13:25:25ID: 21362504

worked!

restarted the /etc/init.d/iptables and worked!!

thanx!

 

by: enrique_salazarPosted on 2008-04-15 at 13:36:12ID: 21362611

20120131-EE-VQP-002

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