Snort mailing list archives

Re: Re : Re: What is the correct syntax for bpf_file?


From: Miguel Alvarez <miguellvrz9 () gmail com>
Date: Tue, 29 Jan 2013 22:05:54 +0100

snort-2.9.4 with libpcap 1.3.0.  And you're right, running 'tcpdump -i
<iface> -vvnn src host 10.10.1.1' doesn't return anything but the alerts
keep getting logged.  Why is that?!

Cheers,

MA


On Tue, Jan 29, 2013 at 6:53 PM, Rm Kml <rmkml () yahoo fr> wrote:

Thx, Im curious what is your snort version please ?
Maybe you have vlan ?
For example can you write network trafic with tcpdump like and replay file
on tcpdump + snort with bpf ?
Do you have same pb if you add bpf instructions on snort cmd line ?
Regards
Rmkml

 ------------------------------
* From: * Miguel Alvarez <miguellvrz9 () gmail com>;
* To: * rmkml <rmkml () yahoo fr>;
* Cc: * Snort Users <snort-users () lists sourceforge net>;
* Subject: * Re: [Snort-users] What is the correct syntax for bpf_file?
* Sent: * Tue, Jan 29, 2013 4:59:20 PM

  Thanks for the reply.  I just have one line just to test:

not src host (10.10.1.1)

But it's still triggering alerts after restarting snort.

01/29-16:56:07.106637  [**] [1:2010937:2] ET POLICY Suspicious inbound to
mySQL port 3306 [**] [Classification: Potentially Bad Traffic] [Priority:
2] {TCP} 10.10.1.1:39944 -> 10.42.1.0:3306

Any ideas?  I am very familiar with bpf syntax and use it on the command
line with tcpdump all the time so this is very confusing!

Thank you,

MA


On Tue, Jan 29, 2013 at 5:44 PM, rmkml <rmkml () yahoo fr> wrote:

Hi Miguel,
Please try this bpf: 'not src host (10.10.1.1 or 10.10.1.2 or 10.10.1.3)'
Regards
Rmkml




On Tue, 29 Jan 2013, Miguel Alvarez wrote:

 I have a list of my nessus scanners in my /etc/snort/bpf_file but
they're still triggering alerts.  I've got them listed in the following
syntax for example:
not (src host 10.10.1.1) &&
not (src host 10.10.1.2) &&
not (src host 10.10.1.3)

And my snort process is pointing to it:

/usr/sbin/snort -D -i eth6 -u snort -g snort -c /etc/snort/snort.conf -l
/var/log/snort/eth6 -F /etc/snort/bpf_file

And it shows up in the syslog when snorts starts:

Jan 29 16:15:53 nids1 snort[940]: Reading filter from bpf file:
/etc/snort/bpf_file
Jan 29 16:15:53 nids1 snort[940]: Snort BPF option: not (src host
10.10.1.1) &&
not (src host 10.10.1.2) &&
not (src host 10.10.1.3)

But the alerts keep streaming in (not just this alert):

01/29-16:36:28.235294  [**] [1:2003068:6] ET SCAN Potential SSH Scan
OUTBOUND [**] [Classification: Attempted Information Leak] [Priority: 2]
{TCP} 10.10.1.1:49870 -> 10.10.1.43:22

This is snort 2.9.4.0 on CentOS 5.x.  What am I doing wrong?

Thank you!

MA



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