Deny large number of IPs via ipfw

Dan Mahoney, System Admin danm at
Sun Jun 11 14:42:44 UTC 2006

On Sun, 11 Jun 2006, fbsd wrote:

> Using such an list of ip address from a major rbl is flawed at the
> core of the idea.
> Over 85% of those 3 million ip address are spoofed in the first
> place.
> Most are what would be called false positives.
> Reread the info at the source it says the data is
> not intended to be used the way you are trying to use it.

All it says is: "We're getting a lot of reports of spurious blocking 
caused by sites using the CBL to block authenticated access to smarthosts 
/ outgoing mail servers. THE CBL is only designed to be used on INCOMING 
mail, i.e. on the hosts that your MX records point to."

Which I take to mean, yeah, if you're using it on sendmail, you allow SMTP 
AUTH to override blacklists (this is the case by default.)

Whereas my intention would be to use it to block ports such as 80 and 22. 
Every system I've found trying to brute-force SSH on my box has already 
been in this database, and by using mod_access_rbl for apache I was able 
to catch and block a dozen or so attempts to post spammish content to 
guestbooks and the like (but I'd like to do this without the overhead of 
apache DNS lookups).

Thanks for your input, though.


> You really need to rethink what you are doing.
> -----Original Message-----
> From: owner-freebsd-questions at
> [mailto:owner-freebsd-questions at]On Behalf Of Dan
> Mahoney,
> System Admin
> Sent: Sunday, June 11, 2006 8:36 AM
> To: questions at
> Subject: Deny large number of IPs via ipfw
> Hey all,
> I've got a file that I just synced from a major RBL, and I'd like to
> just
> use it to globally deny access to my system.  Is there an easy way
> to do
> this within ipfw -- the file is about 3 *million* lines, and is from
> -Dan
> --
> -The Chest of the nameless streaker of the 1998 Grammy Awards' Bob
> Dylan
> Performance.
> --------Dan Mahoney--------
> Techie,  Sysadmin,  WebGeek
> Gushi on efnet/undernet IRC
> ICQ: 13735144   AIM: LarpGM
> Site:
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"Well, what was it then?"

"I think it was some mixture of Rubbing Alcohol, and Desenex(TM) Foot
Powder, because my feet feel okay, and my back doesn't hurt, but my
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-Dan Mahoney, Costa Rica, August 12th, 1994

--------Dan Mahoney--------
Techie,  Sysadmin,  WebGeek
Gushi on efnet/undernet IRC
ICQ: 13735144   AIM: LarpGM

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