Snort mailing list archives

Re: [Hogwash-devel] Re: what is the difference between these rules!??!?!


From: allen <aef () prismnet com>
Date: 05 Aug 2002 06:44:25 -0500



Well...

The solution you did below is okay, BUT...

Let's look at the problem a little more closely,
you may decide you want to do things a little
bit different...

PORN ...

The idea is:  "Do not allow browsers to get porn"

In order to get porn, a browser has to request porn.

By and large, mostly what I have seen is rules that
stop the browser from requesting porn, not stopping
the porn from coming in.

You can do this one of two ways or both...

1.  Block the DNS Lookup for the PORN Site

    drop udp $internal > $external <dns port> ( bad site data value(s) )

2.  Block the browser "GET http://www.badsite.com";
    

Again, you may wish to take a closer look at Squid and SquidGuard.

A Proxy can make it much EASIER to write rules that block Porn.

Hogwash is really better at blocking attack signatures and viri.

I'm SERIOUS.  SquidGuard is probably WHAT YOU WANT for the 
PORN problem.

That doesn't mean don't use Hogwash, just that you'd have to 
write LOTS OF RULES in Hogwash and you probably couldn't do
a perfect job of it.

Unless you knew the exact binary signature of each image that
has porn on it...  see.. that's what hogwash does... filters
exact based on content...  each individual content...

With SquidGuard you can write "expressions" like "Don't let the 
browser request anything that sounds like "xxx".

Just a few expressions like that can lock things down pretty well.

Hogwash has more difficulty in rule writing for THAT PURPOSE.

That is my impression of things.  Hogwash = Security Tool, not exactly
Anti-Porn Tool...  "Not 'best' suited for that purpose"

Additionally, SquidGuard already has a database of Porn sites to
block... 100,000+ entries...

Wanna write that many hogwash rules ?

-AEF



On Mon, 2002-08-05 at 02:29, funky wrote:

Hi,

I'm making the test at my home using ppp0 for external
interface and eth0 for internal interface. It works at
all:)

Can you explain my my the porn.rules ruleseare written
as below:
alert tcp $EXTERNAL_NET 80 -> $HOME_NET any /
(msg:"Game site in not
allowed!!";content:"tavla";nocase;flags:A+)

this is only for making alerts and loggging?!?!
If i wanna block a site, i.e. www.site.com , how can
it be made?!? Is the solution below is good?? Or can
you tell me a better rule!? :
drop tcp any any <> any any /
(msg:"Game site is not allowed!!";
content:"www.site.com";)

thanx

funky



--- Matt Kettler <mkettler () evi-inc com> wrote:
How are you physically configured? Is the network
traffic in question 
running *through* your snort box (ie: the machine
running snort acts as a 
router with 2 network cards), or alongside it?
Hogwash will only work if 
your snort box is an in-line router, and will not
work as a 
single-interface side-monitor connected via a hub or
ethernet tap.


Hogwash will only work if configured like this:

internet ---- snort_hogwash_machine ---  protected
machine

it will not work like this:

internet ------ hub/tap ------ "protected" machine
(not really protected)
                 |
          snort_hogwash_machine.

The second setup works for normal snorting, but does
not work for 
hogwashing since the snort machine can only see the
packets in question, it 
can't block them since it's not "in line". If the
second case is your only 
possible configuration, your best bet is flexresp,
but that works by 
spoofing reset packets and does not work 100%
reliably.



At 10:42 AM 8/3/2002 -0700, funky wrote:

Hi,

I'm trying to block some sites using the hogwash
patch
for Snort.

I tried the rule below like the porn.rules:

drop tcp $EXTERNAL_NET 80 -> $HOME_NET any /
(msg:"Game site in not
allowed!!";content:"tavla";nocase;flags:A+)

Tyring to enter a web-site froma client, for
exemple
www.tavla.com, i can enter that, why!?!??!?!
i have to modify the rule like below in order to
block
the site:

drop tcp any any <> any any /
(msg:"Game site is not allowed!!";
content:"tavla";)

Now i'M not allowed to enter the sites.
So do i have to modify the rules like that which i
wanna apply the "drop" option!??!??!

Anyone can help me in that case please?!?!?

thanx

funky
Istanbul




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