A linux machine is collecting data from 3 equipments using sockets.
The data is collected using the port 502 on those equipments.

After the system boot, and using nmap using the equpments's ip address
the return is

PORT    STATE    SERVICE
21/tcp  open  ftp
23/tcp  open  telnet
502/tcp open  asa-appl-proto

After some time (typically  48 hours) the ports are all filtered,
without any user intervention.

PORT    STATE    SERVICE
21/tcp  filtered ftp
23/tcp  filtered telnet
502/tcp filtered asa-appl-proto

There is no firewall ("service iptables status" gives "Firewall is
stopped.").
There are 3 applications reading data from those 3 equipments each 5
seconds.
There is also a apache and mysql server running.

Any idea why the ports are filtered?

Thanks.

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On 30 Nov 2006 00:13:19 -0800
"Oliveira" <emanuel.oliveira@mobrob.com> wrote:

> A linux machine is collecting data from 3 equipments using sockets.
> The data is collected using the port 502 on those equipments.
>
> After the system boot, and using nmap using the equpments's ip address
> the return is
>
> PORT    STATE    SERVICE
> 21/tcp  open  ftp
> 23/tcp  open  telnet
> 502/tcp open  asa-appl-proto
>
> After some time (typically  48 hours) the ports are all filtered,
> without any user intervention.
>
> PORT    STATE    SERVICE
> 21/tcp  filtered ftp
> 23/tcp  filtered telnet
> 502/tcp filtered asa-appl-proto
>
> There is no firewall ("service iptables status" gives "Firewall is
> stopped.").
> There are 3 applications reading data from those 3 equipments each 5
> seconds.
> There is also a apache and mysql server running.
>
> Any idea why the ports are filtered?

filtered means not responding. so it's not responding.

--
Regards, Ed                      :: http://www.gnunix.net
proud Java hacker
The previous Iraqi regime collapsed within one hour of Mr. T pitying
Saddam Hussein

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