[Snort-users] Re: execute external program

Simon Biles simon.biles at ...11827...
Thu Oct 13 01:55:08 EDT 2005


Use alert_unixsock and alert to a socket, then write a small program
to listen to the socket, and run whatever application that you choose
upon reciept of the trigger.

Below is a quick bit of Perl to listen to a socket ...


# Include the socket libraries

use IO::Socket;

# This is the template to capture the Alert Name
# Edit this to get the additional packets.

$TEMPLATE = "A256 A*";

# Release the socket if it already exists

unlink "/var/log/snort/snort_alert";

# In case of user termination - exit gracefully.

$SIG{TERM} = $SIG{INT} = sub { exit 0 };

# Open up the socket.
my $client = IO::Socket::UNIX->new(Type => SOCK_DGRAM,
                   Local => "/var/log/snort/snort_alert")
  or die "Socket: $@";

print STDOUT "Socket Open ... \n";

# Loop receiving data from the socket, pulling out the
# alert name and printing it.

my $data;

while ( true ) {
    @FIELDS = unpack($TEMPLATE, $data);

# Insert your code here to do whatever ....

    print "@FIELDS[0] \n";


# At termination close up the socket again.

END {unlink "/var/log/snort/snort_alert";}

Have fun,



On 10/12/05, Matt Kettler <mkettler at ...4108...> wrote:
> Gaston Martres wrote:
> > Hi.
> >
> > I was wondering if is possible to execute an external program when a
> > event or alert in snort is triggered.
> >
> > I was looking on google, but, or I have searched in a wrong way or this
> > is not possible.
> It is not possible. See the FAQ on getting snort to email you.
> Executing a process directly from snort is so expensive it would bog snort
> down
> and cause it to miss a very substantial number of packets.
> In general a better way is to use swatch or logsurfer to monitor the snort
> logs
> and trigger processes. This is a little less "real-time", but it should
> happen
> within a hundred milliseconds or so.
> http://www.snort.org/docs/faq/1Q05/node94.html
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Simon Biles
CISSP, OPSA, BS7799 Lead Auditor, MBCS

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