i need a working example of java code that intercepts incomming
tcp/ip packets modifies it and intercepts outgoing tcpip packets and
modifies them.  I need to modify the source and target ip of the
packets in the headers.

I saw a few projects over the net but could make non of them working

some links:

http://netresearch.ics.uci.edu/kfujii/jpcap/doc/faq.html - no modification
http://www.savarese.org/software/vserv-tcpip/
http://66.102.9.104/search?q=cache:2gVkHjhxa8cJ:www.secdev.org/conf/scapy_Aachen.pdf+packets+manipulation&hl=iw&gl=il&ct=clnk&cd=3&client=firefox-a
http://www.secdev.org/projects/scapy/#demo
jpwrite in sourceforge - no sources no files
http://jpckt32.sourceforge.net/
http://sourceforge.net/search/?type_of_search=soft&words=java+packet
http://www.velocityreviews.com/forums/t149914-java-version-of-tcpdump.html
://www.google.co.il/search?q=manipulate+packets+java&btnG=%D7%97%D7%99%D7%A4%D7%95%D7%A9&hs=nHa&hl=iw&client=firefox-a&rls=org.mozilla%3Aen-US%3Aofficial

if you can manage to have such a code please provide me with how to
install it and test it.

10x

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Clarification of Question by tomerbd1-ga on 09 Aug 2006 22:10 PDT

Note that the original packet should not be sent but only the
manipulated one, same for received packets, they should not be
received by only the manipulated one. (manipulated with source ip and
destination ip)