pcap_lookupdev(3PCAP) man page

Updated: 8 September 2017 • View in plain textReturn to Main Contents

This man page documents libpcap version 1.11.0-PRE-GIT (see also: 1.10.4, 1.10.2, 1.10.1, 1.10.0, 1.9.1, 1.8.1, 1.7.4, 1.6.2, 1.5.3).

Your system may have a different version installed, possibly with some local modifications. To achieve the best results, please make sure this version of this man page suits your needs. If necessary, try to look for a different version on this web site or in the man pages available in your installation.


pcap_lookupdev - find the default device on which to capture


#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

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


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 NULL.

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, NULL is returned and errbuf is filled in with an appropriate error message.




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.


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