nic

Reads bytes from a network interface card (NIC).

Synopsis

nic <iface> [-s|--snaplen <count>] [-e|--emit-file-headers]

Description

The nic loader uses libpcap to acquire packets from a network interface and packs them into blocks of bytes that represent PCAP packet records.

The received first packet triggers also emission of PCAP file header such that downstream operators can treat the packet stream as valid PCAP capture file.

The default parser for the nic loader is pcap.

-s|--snaplen <count>

Sets the snapshot length of the captured packets.

This value is an upper bound on the packet size. Packets larger than this size get truncated to <count> bytes.

Defaults to 262144.

-e|--emit-file-headers

Creates PCAP file headers for every flushed batch.

The nic connector emits chunk of bytes that represent a stream of packets. When setting --emit-file-headers every chunk gets its own PCAP file header, as opposed to just the very first. This yields a continuous stream of concatenated PCAP files.

The pcap parser can handle such concatenated traces, and optionally re-emit thes file headers as separate events.

Examples

Read PCAP packets from eth0:

from nic eth0

Perform the equivalent of tcpdump -i en0 -w trace.pcap:

load nic en0 | save file trace.pcap