Hello, 

I'm back.  Perhaps against Charles Steinkuehler's
advice (since I'm a bit of a packet filter newbie) but
with Steve Jeppesen's recommendation to browse the
archives of this list, I have LaBrea up and running on
a single IP as follows:

1. edit /etc/init.d/LaBrea to run LaBrea with options

-i eth0 -l -p 80000 -z -x -F /etc/Labrea.bpf

2. create file /etc/LaBrea.bpf containing

dst host my.ext.IP.no
  and tcp[2:2] & 0xfc00 == 0

which supposedly limits LaBrea only to tcp packets 
directed at my IP between ports 0 and 1024 (I am not
forwarding or running any services) 

3. Let LaBrea go out of promiscuous mode by commenting
out the call to ifconfig in /etc/init.d/LaBrea.

It seems to work. I get "Teergrubing ..." messages in
syslog, followed by a slew of denied attempts from the
teergrubed IP.  Problem is, these are getting out of
hand.  My logs are getting horribly choked -
/var/log/messages easily gets up to a Mb in a few
hours.  There is one pernicious machine at
66.100.24.173 that has been hitting me on port 80
every few seconds all weekend.  At least once my LEAF
ram disk has filled up and the system spontaneously
rebooted.  

I'm thinking my valiant little firewall (486, 16Mb
RAM) may not really be suited to tackle these nasty
worms and such, and I should go back to just ignoring
the junk out there.  Which brings me to a thought:
This seems to be a way for worm authors to fight back
at packages like LaBrea - just keep filling up the
logs til the system chokes.  Perhaps they've already
figured this out!?  Or maybe someone is making a
conscious denial of service attack on me because of my
tarpit...

Any thoughts? Are there ways to cut down on LaBrea's
activity? Clearly it would help a lot if I excluded
port 80, but then there wouldn't be much point would
there? 

Jabez


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