pcap_lookupdev(3pcap)

pcap_lookupdev3pcap

Find the default device on which to capture

Usage

#include <pcap/pcap.h>
char errbuf[PCAP_ERRBUF_SIZE];

[DEPRECATED] char *pcap_lookupdev(char *errbuf);

Overview

This interface is obsoleted by pcap_findalldevs(3PCAP). To find a default device on which to capture, call pcap_findalldevs() and, if the list it returns is not empty, use the first device in the list. (If the list is empty, there are no devices on which capture is possible.) errbuf is a buffer large enough to hold at least PCAP_ERRBUF_SIZE chars.

If pcap_init(3PCAP) has been called, this interface always returns a null pointer.

pcap_lookupdev() returns a pointer to a string giving the name of a network device suitable for use with pcap_create(3PCAP) and pcap_activate(3PCAP), or with pcap_open_live(3PCAP), and with pcap_lookupnet(3PCAP). If there is an error, or if pcap_init(3PCAP) has been called, a null pointer is returned and errbuf is filled in with an appropriate error message.

Releases

9 releases since Debian 6.0 (Squeeze); the text changed 5 times.

  1. 6.0–7
  2. 8
  3. 9–10
  4. 11–12
  5. 13
  6. Arch

Bugs

The pointer returned by pcap_lookupdev() points to a static buffer; subsequent calls to pcap_lookupdev() in the same thread, or calls to pcap_lookupdev() in another thread, may overwrite that buffer.

In WinPcap and Npcap, this function may return a UTF-16 string rather than an ASCII or UTF-8 string.

From libpcap 1.11.0-1 in Arch Linux 2026-11-01. Parsed by carta from the page's man source.