[Snort-users] Snort is not seeing all traffic...

Matt Kettler mkettler at ...4108...
Thu May 8 18:49:08 EDT 2003

At 11:23 PM 5/7/2003 -0400, PJ-ML wrote:
>The ethernet link to hub and to other parts of the network are all 100. 
>Could it be the speed of the server? I am lost in fog. Not sure where to 
>go, I know that I must tune the server...but I do not know what to tune if 
>it is not seeing even purposeful exploits...I will be more than happy  to 
>give any more info that anyone requires to help me figure this out except 
>for  the root password to my machine ;-)

I'd first see if your snort box even has the packets sent to it, using the 
all-seeing tcpdump tool.

run tcpdump -n -i (whatever interface) host (target of attack) and then 
re-run the attack.. does tcpdump spit out packets?

As an example:

snortbox # tcpdump -n -i eth0 host

testbox # attack

snortbox should have packets from the attack dump to the screen. Note that 
the only reason I added -n to the tcpdump commandline is to prevent tcpdump 
from spending a long time trying to do reverse DNS lookups. If there's no 
DNS available tcpdump can hold off printing packets to the screen for a 
shockingly long time.

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