Re: [Simple-evcorr-users] read/write operations through named pipe

2010-12-08 Thread Risto Vaarandi
Am I understanding correctly that you want to write some of the data
from named pipe to an external log? Since SEC is already reading from
the pipe, it's a bad idea to start another process that reads the same
pipe, since reading removes data from pipe.
If would recommend a separate rule that would match each SEC input
event and write to a separate file with write action. For example:

type=single
ptype=RegExp
pattern=.?
desc=write each input line to a separate file
action=write /var/log/sec-monitor.log $0

regards,
risto

2010/12/8 M Haris Farooque :
> hello guys,
> I have another question related to Named Pipe.
> I have made a "/usr/local/etc/SEC_Log_Pipe " and hang it with SEC so that
> SEC can read input text from it;
>
> cmd1:    perl -w /usr/local/sbin/sec.pl --conf=xxx.cfg --conf=yyy.cfg
> --conf=zzz.cfg -input=/usr/local/etc/SEC_Log_Pipe -intevents
>
> I need to log some information also in a log file upon successful execution
> of one of my defined rule and i wanted to use the same pipe for writing it.
>
> I wrote the following script for writing;
>
> open(NAMEDPIPE, "+< $filename") or die "fifo  $!";
> $| = 1;
>
> while ()
> {
>         print  $_;
> }
>
> and executed it as a background process like this;
> cmd2:    perl sec_log_pipe.pl >> /var/log/sec_monitor.log &
>
> but 2 seperate processes are created. (lsof /usr/local/etc/SEC_Log_Pipe
> shows both processes). One processes is created by SEC i.e.  for
> taking Input and another by  for logging out data to a log file.
> Since, I always execute cmd2 after cmd1 so, logging is working fine, but SEC
> is not able to take any input unless I kill the process (cmd2).
>
> action statement in my rule set is;
>     type=Single
>     ptype=RegExp
>     patter=blah,blah
>     desc=$0
>     action= write /usr/local/etc/SEC_Log_Pipe [%u] %s
>
> Is there a good way to handle read/write operations through named pipe?
> Thanks in advance,
> --
>
> Kind Reagrds/Mit freundlichen Grüßen
>
> M Haris Farooque
>
> --
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Re: [Simple-evcorr-users] read/write operations through named pipe

2010-12-08 Thread John P. Rouillard

In message <4cffa586.70...@fleetboard.com>,
M Haris Farooque writes:
>I have another question related to Named Pipe.
>I have made a "/usr/local/etc/SEC_Log_Pipe " and hang it with SEC so=20
>that SEC can read input text from it;
>
>*cmd1*: /perl -w /usr/local/sbin/sec.pl --conf=3Dxxx.cfg --conf=3Dyyy.cfg=
>=20
>--conf=3Dzzz.cfg -input=3D/usr/local/etc/SEC_Log_Pipe -intevents/
>
>I need to log some information also in a log file upon successful=20
>execution of one of my defined rule and i wanted to use the same pipe=20
>for writing it.
> [...]
>Is there a good way to handle read/write operations through named pipe?
>Thanks in advance,

The result of using multiple readers on a fifo/named pipe differes
from OS to OS, but IIRC only one process will sucessfully read from
the pipe in most cases. The fifo doesn't duplicate any data. Once the
data is read by a process it is gone.

I would just use two seperate fifo/named pipes.

Also note that writing to a fifo/named pipe can block if there is no
reader so you have to be careful when using the write action to
directly write to a fifo so that it doesn't hang the SEC process.

--
-- rouilj
John Rouillard
===
My employers don't acknowledge my existence much less my opinions.











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Re: [Simple-evcorr-users] read/write operations through named pipe

2010-12-08 Thread Risto Vaarandi
On 12/08/2010 06:45 PM, John P. Rouillard wrote:
>
> In message<4cffa586.70...@fleetboard.com>,
> M Haris Farooque writes:
>> I have another question related to Named Pipe.
>> I have made a "/usr/local/etc/SEC_Log_Pipe " and hang it with SEC so=20
>> that SEC can read input text from it;
>>
>> *cmd1*: /perl -w /usr/local/sbin/sec.pl --conf=3Dxxx.cfg --conf=3Dyyy.cfg=
>> =20
>> --conf=3Dzzz.cfg -input=3D/usr/local/etc/SEC_Log_Pipe -intevents/
>>
>> I need to log some information also in a log file upon successful=20
>> execution of one of my defined rule and i wanted to use the same pipe=20
>> for writing it.
>> [...]
>> Is there a good way to handle read/write operations through named pipe?
>> Thanks in advance,
>
> The result of using multiple readers on a fifo/named pipe differes
> from OS to OS, but IIRC only one process will sucessfully read from
> the pipe in most cases. The fifo doesn't duplicate any data. Once the
> data is read by a process it is gone.
>
> I would just use two seperate fifo/named pipes.
>
> Also note that writing to a fifo/named pipe can block if there is no
> reader so you have to be careful when using the write action to
> directly write to a fifo so that it doesn't hang the SEC process.

John has made an important point here -- the lack of reader stalls the 
entire SEC process. And if one opens fifo in nonblocking mode, data loss 
might occur. Since the idea seems to be write some lines into a separate 
file, I'd recommend to do it from the SEC rule with 'write' action.
kind regards,
risto

>
> --
>   -- rouilj
> John Rouillard
> ===
> My employers don't acknowledge my existence much less my opinions.
>
>
>
>
>
>
>
>
>
>
>
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