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Re: Network Variables
From: James Lay <jlay () slave-tothe-box net>
Date: Thu, 02 May 2013 13:08:07 -0600

Nicely done Waldo.

James

On 2013-05-02 13:00, waldo kitty wrote:
On 5/2/2013 13:23, Seth Dunn wrote:
So now my question comes, since you were wondering about the rule I 
was
using.
This is my rule::
not net 10.10.0.0/24 and dst host 10.75.45.1&&  dst port 80 or not 
net
10.30.0.0/24 and dst host 10.75.45.1&&  dst port 80

ok, i'm going to try to break this down and interpret your wants one
section at
a time...

By my understanding, and my desire to see happen is this.
Traffic from the network 10.10.0.0/24 going to http at 10.75.45.1 
should
be ignored.

(net 10.10.0.0/24 and (host 10.75.45.1 and port 80))

Also, traffic from the network 10.30.0.0/24 going to http at 
10.75.45.1
should be ignored.

(net 10.30.0.0/24 and (host 10.75.45.1 and port 80))

All other traffic is still monitored.

the above should qualify your two wants... now, let's streamline them
a bit to
make it more legible...

first, let's combine the two source networks into one statement...

net (10.10.0.0/24 or 10.30.0.0/24)

now the destination host and destination port...

host 10.75.45.1 and port 80

then combine those two lines...

net (10.10.0.0/24 or 10.30.0.0/24) and host 10.75.45.1 and port 80

and lastly negate the whole thing by enclosing it in parens with
'not' on the
outside...


not (net (10.10.0.0/24 or 10.30.0.0/24) and host 10.75.45.1 and port 
80)


plug that line into your bpf with the double quotes or whatever you
need to wrap
around it and see what happens ;)


FWIW: this was minimally tested on my network via tcpdump and
manually checking
the pcap with wireshark...

NOTES:
1. using 'src net' and 'dst host' plus 'dst port' resulted in only
the traffic
/to/ the server being ignored but all the traffic from the server was 
seen...

2. removing the 'src' and 'dst' designators denotes all traffic in 
both
directions that fits the mask (if i can use that term to describe
this object)...

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It's a free troubleshooting tool designed for production
Get down to code-level detail for bottlenecks, with <2% overhead.
Download for free and get started troubleshooting in minutes.
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