Re: How to drop an idle connection with iptables?

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Hi Nikolay:
    Thanks greatly for your information.

On 2011-11-25 22:20, Nikolay Kichukov wrote:
Hash: SHA1

just googled what you're after and bumped to:


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:

     Even some web page indicated that iptables can drop idle connection, such as the tcp section of

     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?


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