PCAP_LOOKUPNET(3)

🌸 NAME 🌸

okay bestie, welcome to the pcap_lookupnet page from the Library Functions Manual 💖 — it's here to find the IPv4 network number and netmask for a device. That's the whole vibe. periodt ✨

✨ SYNOPSIS ✨

literally drop this in:

#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

int pcap_lookupnet(const char *device, bpf_u_int32 *netp,
           bpf_u_int32 *maskp, char *errbuf);

🦋 DESCRIPTION 🦋

okay so pcap_lookupnet()? It's the function that determines the IPv4 network number and mask associated with the network device device. No cap. 🫶

Both netp and maskp are bpf_u_int32 pointers. And errbuf? That's a buffer large enough to hold at least PCAP_ERRBUF_SIZE chars. Got it? Good. 💅

🚨 real talk bestie: this function is not available on Windows. It supports neither IPv6 nor multiple IPv4 addresses per interface, which obviously is not practical in modern networks. See pcap_findalldevs(3) for a more elaborate solution to the problem 👀.

💅 RETURN VALUE 💅

pcap_lookupnet() returns 0 on success and PCAP_ERROR on failure. If PCAP_ERROR is returned, errbuf is filled in with an appropriate error message. slay, that's the contract ✨

🎀 SEE ALSO 🎀

• pcap(3) — go peek, bestie 👑

mwah 💋 — this is the PCAP_LOOKUPNET(3) page from the Library Functions Manual, dated 13 March 2024 🌈