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load_nic

Loads bytes from a network interface card (NIC).

load_nic iface:str, [snaplen=int, emit_file_headers=bool]

Description​

The load_nic operator 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.

iface: str​

The interface to load bytes from.

snaplen = int (optional)​

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 snaplen bytes.

Defaults to 262144.

emit_file_headers = bool (optional)​

Creates PCAP file headers for every flushed batch.

The operator 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​

load_nic "eth0"
read_pcap

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

load_nic "en0"
read_pcap
write_pcap
save_file "trace.pcap"