ipfw along with netstat

[Nikola Stojanoski]

Hi,

it will count the number of established sessions from a host or to a host, 
so if you set it:
ipfw add allow tcp from any to me 80 limit dst-addr 10
it will limit to 10 established connection to your http server from any ip

and if you set it like this:
ipfw add allow tcp from any to any 80 limit src-addr 10
it will limit to 10 established connections to your http server from 1 ip

or you can use:
ipfw add allow tcp from any to any 80 limit src-addr 10
ipfw add allow tcp from any to me 80 limit dst-addr 100
so you will limit 10 established connections per ip, and maximum 100 
connections to your http server

also if you do ssh or some other limiting you should add anti-locking rule 
so you can login if you are flooded it's something like this:
ipfw add allow tcp from local/net to any 22
ipfw add allow tcp from any to any 22 limit src-addr 10
ipfw add allow tcp from any to me 22 limit dst-addr 100
this way you will not limit connections from your local net and if you get 
flooded you can login to your box

i hope you will find this usefull

Regards

----- Original Message ----- 
From: "Jordi Moles" <jordi at cdmon.com>
To: "Nikola Stojanoski" <nikola at vlaeonline.com>
Cc: <freebsd-ipfw at freebsd.org>
Sent: Tuesday, February 27, 2007 5:02 PM
Subject: Re: ipfw along with netstat


> hi,
>
> thanks for the information, it works great!!
>
> I've got another question related to this... how does ipfw actually count 
> the number of ip addresses? I mean... let's say i set up the firewall to 
> only accept 50 connections. ? does it count 50 connexions per second? 50 
> during a minute? or what?
>
> thanks.
>
> En/na Nikola Stojanoski ha escrit:
>> you can use limit for that. here is the part about limit in ipfw manual:
>>
>>     limit {src-addr | src-port | dst-addr | dst-port} N
>>             The firewall will only allow N connections with the same set 
>> of
>>             parameters as specified in the rule.  One or more of source 
>> and
>>             destination addresses and ports can be specified.
>>
>> so a simple way to limit max connections per ip is:
>>
>> ipfw add allow ip from any to any limit src-addr 100
>>
>> this way you will limiit yourself also with 100 connections per ip, but 
>> you can play around with recv, xmit, via and other settings to fit your 
>> needs
>>
>> Regards
>>
>> ----- Original Message ----- From: "Jordi Moles" <jordi at cdmon.com>
>> To: <freebsd-ipfw at freebsd.org>
>> Sent: Monday, February 26, 2007 10:36 AM
>> Subject: ipfw along with netstat
>>
>>
>>> hi,
>>>
>>> I've done a lot of research about that but found anything like i need. 
>>> I'm running an ipfw firewall on a FreeBSD 6.1 and i wonder if ipfw can 
>>> add rules automatically when it detects, for example, that an ip address 
>>> has 100 connections open in the server. I'm doing a similar thing with a 
>>> perl script and netstat. The script counts how many connections an ip 
>>> address opened and it automatically adds a new rule to the firewall, but 
>>> I'm looking for a way in which ipfw does that on its own.
>>>
>>> thank you.
>>> _______________________________________________
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>>> http://lists.freebsd.org/mailman/listinfo/freebsd-ipfw
>>> To unsubscribe, send any mail to "freebsd-ipfw-unsubscribe at freebsd.org"
>>
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