netsniff-ng is a free Linux networking toolkit, a Swiss army knife for your daily Linux network plumbing if you will. Its gain of performance is reached by zero-copy mechanisms, so that on packet reception and transmission the kernel does not need to copy packets from kernel space to user space and vice versa.

The toolkit consists of the following utilities:

• netsniff-ng, a fast zero-copy analyzer, pcap capturing and replaying tool
• trafgen, a multithreaded low-level zero-copy network packet generator
• mausezahn, high-level packet generator for HW/SW appliances with Cisco-CLI*
• bpfc, a Berkeley Packet Filter compiler, Linux BPF JIT disassembler
• ifpps, a top-like kernel networking statistics tool
• flowtop, a top-like netfilter connection tracking tool
• curvetun, a lightweight curve25519-based IP tunnel
• astraceroute, an autonomous system (AS) trace route utility

This toolkit can be used for network development and analysis, debugging, auditing or network reconnaissance. You can read more and download this tool over here: http://netsniff-ng.org