Unix Programming - nmap - filtered, why?

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Author nmap - filtered, why?
Oliveira

2006-11-30, 7:27 am

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.

ed

2006-11-30, 1:17 pm

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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