security at admin.fulgan.com
Thu Nov 8 10:02:59 GMT 2001
LF> RE: In any case, you should try to catch the outgoing
>> SYN packet: it will
>> tell you what protocol is concerned and you'll be
>> able to act on that.
LF> Could yo tell how I can act once I know the protocol?
Well, it really depends on what the SYN will tell you. Basically, you
have two choices: Bane the guilty application by closing it's outgoing
port (the target port in the SYN packet) or try to work out a behavior
rule for the application, if it can be applied (Some applications
allow you to specify that you're behind a NAT router and will stop
sending internal addresses).
Another thing you can do is to filter packet to private IP ranges at
your router: that way, they won't be reaching the external network.
Depending on how your router's filter behave, you might still get the
network unreachable packets, but only from your own router.
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