keep-alive in sqlhosts
Hi all,
we have the problem that longer lasting remote client sessions on informix
databases are interrupted by the firewalls, particulary when no packets were
sent. It's possible to configure the port on the firewall to extend the time
before the connection is interrupted. The disadvantage is that you never know
if the time you choose is long enough or if you found all database-server
ports.
We found a parameter which can be set in the sqlhosts file of the server, if I
understand aright.
From http://www-01.ibm.com/support/docview.wss?uid=swg21160988
To enable the keep-alive option for an Informix database server TCP port,
specify k=1 in the fifth column of the related line of the server in the
sqlhosts file. The following table is a summary of possible setting of the
keep-alive option in an IBM Informix server sqlhosts file and its results.
k setting in the options field Result
k=0 Disables keep-alive feature: this means the local TCP driver does not
check whether a connection is active. For example, from a PC, if you make a
connection to an IBM Informix database server, and then switch off the PC,
then netstat -a and onstat -u
shows the TCP and database network connection are still established. The TCP
connection is never terminated until stopping and restarting the Informix
server.
k=1 Enables the keep-alive feature
My question: Does this setting solve the issue? Or can it cause unexpected
side-effects.
Thanks,
Reinhard Habichtsberg
Dienstleistungsverantwortlicher IT-Rechenzentrum
Solaris- und Datenbanksysteme
Abrechnungszentrum Emmendingen
Tel.: 07641/9201-203
This sqlhosts option controls options for newly created sockets.
man setsockopt:
SO_KEEPALIVE
Keeps connections active by enabling the periodic
transmission of messages, if this is supported by the protocol. This option
takes an int value.
If the connected socket fails to respond to these messages, the
connection is broken and threads writing to that socket are notified with a
SIGPIPE signal. This is a Boolean option.
Reading this, I'd say definitely worth a try.
BR,
Andreas
From: "Habichtsberg, Reinhard" <RHabichtsberg@arz-emmendingen.de>
To: ids@iiug.org
Date: 09/05/2017 02:00 PM
Subject: keep-alive in sqlhosts [39807]
Sent by: ids-bounces@iiug.org
Hi all,
we have the problem that longer lasting remote client sessions on informix
databases are interrupted by the firewalls, particulary when no packets
were
sent. It's possible to configure the port on the firewall to extend the
time
before the connection is interrupted. The disadvantage is that you never
know
if the time you choose is long enough or if you found all database-server
ports.
We found a parameter which can be set in the sqlhosts file of the server,
if I
understand aright.
>From http://www-01.ibm.com/support/docview.wss?uid=swg21160988
To enable the keep-alive option for an Informix database server TCP port,
specify k=1 in the fifth column of the related line of the server in the
sqlhosts file. The following table is a summary of possible setting of the
keep-alive option in an IBM Informix server sqlhosts file and its results.
k setting in the options field Result
k=0 Disables keep-alive feature: this means the local TCP driver does not
check whether a connection is active. For example, from a PC, if you make a
connection to an IBM Informix database server, and then switch off the PC,
then netstat -a and onstat -u
shows the TCP and database network connection are still established. The
TCP
connection is never terminated until stopping and restarting the Informix
server.
k=1 Enables the keep-alive feature
My question: Does this setting solve the issue? Or can it cause unexpected
side-effects.
Thanks,
Reinhard Habichtsberg
Dienstleistungsverantwortlicher IT-Rechenzentrum
Solaris- und Datenbanksysteme
Abrechnungszentrum Emmendingen
Tel.: 07641/9201-203
*******************************************************************************
Forum Note: Use "Reply" to post a response in the discussion forum.
It will solve the issue (unless the firewall is configured to ignore it,
but I've never seen any case of that).
HOWEVER... the option in Informix side "asks" the OS to send the probes.
When (with which interval), the answer timeout etc. is entirely the OS
responsability... and in many situations the defaults are around 2H, and
most situations I've seen the firewalls "kill" the connections after 1H...
if you find yourself into this situation, the feeling you'll get it that it
didn't work... when in fact it's just misconfiguration.
You should check the OS documentation on how to configure the keep alive
functionality... I've been involved in linux and hp-ux in the past... but
if you need assistance, please tell us your OS.
Note that after you change SQLHOSTS you need to at least restart the
listener (if your Informix version has this functionality). Checking if the
option is in effect can be trivial (lsof) in most operating systems, but is
nearly a nightmare on Linux... one option is to compile and load a kernel
module.... but I always have the feeling there's another option, which I
never remember... maybe some obscure option of netstat... another option
would be to sniff the trafic...
Regards.
On Tue, Sep 5, 2017 at 12:59 PM, Habichtsberg, Reinhard <
RHabichtsberg@arz-emmendingen.de> wrote:
> Hi all,
>
> we have the problem that longer lasting remote client sessions on informix
> databases are interrupted by the firewalls, particulary when no packets
> were
> sent. It's possible to configure the port on the firewall to extend the
> time
> before the connection is interrupted. The disadvantage is that you never
> know
> if the time you choose is long enough or if you found all database-server
> ports.
>
> We found a parameter which can be set in the sqlhosts file of the server,
> if I
> understand aright.
>
> >From http://www-01.ibm.com/support/docview.wss?uid=swg21160988
>
> To enable the keep-alive option for an Informix database server TCP port,
> specify k=1 in the fifth column of the related line of the server in the
> sqlhosts file. The following table is a summary of possible setting of the
> keep-alive option in an IBM Informix server sqlhosts file and its results.
> k setting in the options field Result
>
> k=0 Disables keep-alive feature: this means the local TCP driver does not
> check whether a connection is active. For example, from a PC, if you make a
> connection to an IBM Informix database server, and then switch off the PC,
> then netstat -a and onstat -u
> shows the TCP and database network connection are still established. The
> TCP
> connection is never terminated until stopping and restarting the Informix
> server.
>
> k=1 Enables the keep-alive feature
>
> My question: Does this setting solve the issue? Or can it cause unexpected
> side-effects.
>
> Thanks,
>
> Reinhard Habichtsberg
> Dienstleistungsverantwortlicher IT-Rechenzentrum
> Solaris- und Datenbanksysteme
> Abrechnungszentrum Emmendingen
> Tel.: 07641/9201-203
>
>
> ************************************************************
> *******************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
--
Fernando Nunes
Portugal
http://informix-technology.blogspot.com
My email works... but I don't check it frequently...
Fernando, Andreas,
we use Solaris 10 and as you said the interval is 2H. The command to show is
/usr/sbin/ndd -get /dev/tcp tcp_keepalive_interval. You will see milliseconds.
In our case 7200000.
Yes, we'll try it. k=1 is part of the comma separated options list in fifth
column of sqlhosts.
Thanks,
Reinhard Habichtsberg
Dienstleistungsverantwortlicher IT-Rechenzentrum
Solaris- und Datenbanksysteme
Abrechnungszentrum Emmendingen
Tel.: 07641/9201-203
-----Ursprüngliche Nachricht-----
Von: ids-bounces@iiug.org [mailto:ids-bounces@iiug.org] Im Auftrag von
Fernando Nunes
Gesendet: Dienstag, 5. September 2017 17:17
An: ids@iiug.org
Betreff: Re: keep-alive in sqlhosts [39810]
It will solve the issue (unless the firewall is configured to ignore it, but
I've never seen any case of that).
HOWEVER... the option in Informix side "asks" the OS to send the probes.
When (with which interval), the answer timeout etc. is entirely the OS
responsability... and in many situations the defaults are around 2H, and most
situations I've seen the firewalls "kill" the connections after 1H...
if you find yourself into this situation, the feeling you'll get it that it
didn't work... when in fact it's just misconfiguration.
You should check the OS documentation on how to configure the keep alive
functionality... I've been involved in linux and hp-ux in the past... but if
you need assistance, please tell us your OS.
Note that after you change SQLHOSTS you need to at least restart the listener
(if your Informix version has this functionality). Checking if the option is
in effect can be trivial (lsof) in most operating systems, but is nearly a
nightmare on Linux... one option is to compile and load a kernel module....
but I always have the feeling there's another option, which I never
remember... maybe some obscure option of netstat... another option would be to
sniff the trafic...
Regards.
On Tue, Sep 5, 2017 at 12:59 PM, Habichtsberg, Reinhard <
RHabichtsberg@arz-emmendingen.de> wrote:
> Hi all,
>
> we have the problem that longer lasting remote client sessions on
> informix databases are interrupted by the firewalls, particulary when
> no packets were sent. It's possible to configure the port on the
> firewall to extend the time before the connection is interrupted. The
> disadvantage is that you never know if the time you choose is long
> enough or if you found all database-server ports.
>
> We found a parameter which can be set in the sqlhosts file of the
> server, if I understand aright.
>
> >From http://www-01.ibm.com/support/docview.wss?uid=swg21160988
>
> To enable the keep-alive option for an Informix database server TCP
> port, specify k=1 in the fifth column of the related line of the
> server in the sqlhosts file. The following table is a summary of
> possible setting of the keep-alive option in an IBM Informix server sqlhosts
file and its results.
> k setting in the options field Result
>
> k=0 Disables keep-alive feature: this means the local TCP driver does
> not check whether a connection is active. For example, from a PC, if
> you make a connection to an IBM Informix database server, and then
> switch off the PC, then netstat -a and onstat -u shows the TCP and
> database network connection are still established. The TCP connection
> is never terminated until stopping and restarting the Informix server.
>
> k=1 Enables the keep-alive feature
>
> My question: Does this setting solve the issue? Or can it cause
> unexpected side-effects.
>
> Thanks,
>
> Reinhard Habichtsberg
> Dienstleistungsverantwortlicher IT-Rechenzentrum
> Solaris- und Datenbanksysteme
> Abrechnungszentrum Emmendingen
> Tel.: 07641/9201-203
>
>
> ************************************************************
> *******************
> Forum Note: Use "Reply" to post a response in the discussion forum.
>
>
--
Fernando Nunes
Portugal
http://informix-technology.blogspot.com
My email works... but I don't check it frequently...
*******************************************************************************
Forum Note: Use "Reply" to post a response in the discussion forum.