oops,,,sorry list i forgot to mention that one should manipulate SO_BROADCAST option on UDP sockets. this doesnt work on TCP so you are on your own on that one.. ignore the bogus manner in which it treats bcast addresses. the other info is worth the trade off. v/r ~piranha -----Original Message----- From: piranha Sent: Friday, September 03, 2004 7:23 AM To: 'Netfilter Mailing List' Subject: RE: tcpdump and Iptables netcat (nc shows up under ps) might be usefull... itsa net utility which does I-O across connex using tcp/ip. it can make its paths or driven by other programs like ssh. its got a lot of debug and discovery modules in it so it can (and has) create almost any kind of connection..........and some other `interesting built-ins`. does: any tcp or udp any direction any tcp port any udp port sound godd...wait ther's more.. tunnel with any/all params on/off. excellent at port-scanning YOUR own networks clock controlled buffered send-mode like 1 every X seconds hexdump std<err,out> available which means this stuff can be send to tthe syslogs if desired. and as usual mileage will vary.....make sure you have permission to do this if you aint sure ask again... nufsaid. v/r, ~piranha -----Original Message----- From: netfilter-bounces@xxxxxxxxxxxxxxxxxxx [mailto:netfilter-bounces@xxxxxxxxxxxxxxxxxxx]On Behalf Of Nick Drage Sent: Friday, September 03, 2004 3:23 AM To: netfilter@xxxxxxxxxxxxxxxxxxx Subject: Re: tcpdump and Iptables On Fri, Sep 03, 2004 at 08:41:42AM +0800, cc wrote: > Nick Drage wrote: > >>If I have iptables running and I do a tcpdump -i eth0, at what > >>point is tcpdump listening to the connection? > > > >tcpdump will see the packets before IPTables does anything to them. > > Thanks NIck for the info. Exactly what I wanted to know. Thanks... though Jason's explanation was rather better :) tcpdump is an excellent tool, but ( excuse me if I'm stating the obvious ), don't underestimate the usefulness of the logging rules in IPTables combined with tail -f /var/log/$logfile | grep $string_you_are_looking_for -- mors omnia vincit
