RE: Running snort in daemon mode disables network c onnection

["Sadanapalli, Pradeep Kumar (MED, TCS)" <Pradeep.Sadanapalli () med ge com>]

I tried to run snort with -p option. Now my network interface is not
running in promiscuous mode,
as I found it out by executing "dmesg|tail -10". But still I my network
connection is getting disabled
immediately after running snort. I am not even able to ping to any other
machine in LAN or 
other machines are not able to connect to my machine.

Here is part of my snotd script I am running.

"
# Specify your network interface here
INTERFACE=eth1
LOGDIR=/var/log/snort/
CONFIGFILE=/etc/snort/snort.conf
SNORTBINARY=/usr/local/bin/snort

RETVAL=0

start() {
        echo -n $"Starting snort: "
        daemon $SNORTBINARY -p -A fast -b -l /var/log/snort -d -D -i
$INTERFACE -c $CONFIGFILE
        RETVAL=$?
        [ $RETVAL -eq 0 ] && touch /var/lock/subsys/snortd
        echo
        echo -n $"(log to " $LOGDIR " with configfile " $CONFIGFILE ")"
        echo
}
"

What else may be going wrong? Appreciate your help.
Thanks in advance for all your help

Pradeep



-----Original Message-----
From: Erek Adams [mailto:erek () snort org]
Sent: Friday, February 28, 2003 5:23 PM
To: Sadanapalli, Pradeep Kumar (MED, TCS)
Cc: 'Erek Adams'; 'snort-users () lists sourceforge net'
Subject: Re: [Snort-users] Running snort in daemon mode disables network
connection


On Fri, 28 Feb 2003, Sadanapalli, Pradeep Kumar (MED, TCS) wrote:

> I am running snort-1.9.0 on my redhat linux 8.0 laptop. I am using my
> wireless network card interface to connect to the network. My linux
box
> is connected in the LAN.
>
> I would like to run an Intrusion Detection System and Personal
Wirewall
> on the Linux box, which is just a workstation, not a server.
>
> I want to detect whatever port scans take place on my network
interface(
> whether they are internal to the LAN or external to the LAN) and
report
> it to a central server.

Easy enough.

> I am not using other network interface,eth0. It is just left
unconnected
> to any cable.

No problem.  Forget about it.

> When I am running snort in daemon mode, I am losing my network
> connection. I am not able to connect to any box in the LAN.  Please
help
> me if I am doing something wrong.

It's not Daemon mode that is giving you grief--It's promiscuous mode
that
is.

> What is this promiscuous mode?

To sort of quote "The Red Book" [0]....

'Ethernet is sort of like a "polite" dinner party.  If you want to talk
to
someone, you write the message on a bit of paper, fold it, and on the
outside you write the name of the recipient.  Everyone looks at the
address, but not at what's inside.'

Promiscuous mode is different.  You _read_ all the bits of paper no
matter
who it is for.

Since you just want to look for scans and attacks that are headed to
you,
you don't need promisc mode.  You just want what's destined for your
interface....  Hence, no need of promiscuous mode.

Simply start Snort with the "-p" flag and it should work fine.

Cheers!

-----
Erek Adams

   "When things get weird, the weird turn pro."   H.S. Thompson


[0]
http://www.amazon.com/exec/obidos/tg/detail/-/0131510517/qid=1046473814/
sr=1-2/ref=sr_1_2/104-8282033-5068702?v=glance&s=books

(URL may wrap)


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