Re: How to drop an idle connection with iptables?

[Nikolay Kichukov <hijacker@oldum.net>]

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Hi,
just googled what you're after and bumped to:

http://www.lowth.com/cutter/

HTH

P.S. Our Sonicwall devices have that feature to close established connections when they hit a predefined timeout value
with no data passing through.

- -Nik

On 11/25/2011 03:45 PM, lu zhongda wrote:
> Hi Brian:
> We supply java application server product to our customer.
>     The application server supplies jdbc connection pool functionality to deployed web application.
>     The jdbc connection pool usually keeps a fixed count of physical connections to database which are socket connections.
>     The support staff reflected that the connections in the connection pool were dropped by firewall after 30mins to
> become idle under customer environment .
>     I can't get clear information whether the firewall product is iptables.
> 
>     I googled the topic "firewall drop idle connection" on the Internet, found somebody met the same issue like me even
> though they used the firewall product of cisco
>     such as:
> http://vivekagarwal.wordpress.com/2009/07/04/firewall-dropping-oracle-database-connections-in-websphere-connection-pool/
> 
>     Even some web page indicated that iptables can drop idle connection, such as the tcp section of
> 
> http://www.rigacci.org/wiki/lib/exe/fetch.php/doc/appunti/linux/sa/iptables/conntrack.html
> 
> 
>     I am familiar with Linux, so i want to reproduce the issue with iptables, this is why i posed this topic, I want to
> know whether iptables support this or not.
>     If yes, what is the detailed rule set, if not then that is.
> 
>     As to whether iptables should support this feature, it seems that some product supported this, such as pfsense on
> freebsd or some commercial product.
>     Because I never touch freebsd, so I don't want to use pfsense . From my opinion closing the idle connection can
> avoid the upper application leak idle connection,
>     releasing unused system socket resource. So it is a useful feature if iptables can support this.
> 
>     This is the background for my question and is my real-world use case, haw-haw.
>     Thanks for your help and hope for your answer.
> 
> On 2011-11-25 19:16, Brian J. Murrell wrote:
>> On 11-11-25 12:37 AM, lu zhongda wrote:
>>> On 2011-11-24 19:30, Brian J. Murrell wrote:
>>>> You didn't answer my other question though, which is why do you think
>>>> you need to be dropping idle, yet still ESTABLISHED sessions (and
>>>> breaking higher level protocols when you do that)?
>>> The need to drop idle connection comes from one technical support request:
>> Answering my question of "why do you want to do this" with "because
>> somebody asked" does not really answer the question though.
>>
>> There is an important reason for me to to ask and you to answer the
>> question (i.e. with a real-world use-case) and that's because typically
>> when somebody is proposing to do things that are "strange" or "not as
>> intended" (and indeed which will result in other things breaking -- like
>> TCP in this case) it's because they are trying to solve a problem with
>> the wrong tool.
>>
>> Can you please provide a real-world use-case as to why you'd want/need
>> to stop (i.e. break) an open TCP session?
>>
>> Cheers,
>> b.
>>
> 
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