Packet Analyzers

Ethereal

can we captured packets from a network having host working on different platform ?

How to extract the IP address of a data packet and store it in the database?

A client sends a data packet to the server machine, then how can the server extract the IP address of the data packet .Can you suggest a source code for this above query in JAVA? After extracting the IP address how can the IP address be stored in the database, where other IP addresses of other data...

Need help with packet sniffing

I am doing a sniffer project but I have one problem. This program only receives our host-related packets. I need to know how to receive all packets in the transmission medium. Can anyone help?