pcap_init(3PCAP) man page

Updated: 4 May 2022 • View in plain textReturn to Main Contents

This man page documents libpcap version 1.10.4 (see also: git master branch, 1.10.2, 1.10.1, 1.10.0).

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_init - initialize the library


#include <pcap/pcap.h>

char errbuf[PCAP_ERRBUF_SIZE];

int pcap_init(unsigned int opts, char *errbuf);


pcap_init() is used to initialize the Packet Capture library. opts specifies options for the library; currently, the options are:
Treat all strings supplied as arguments, and return all strings to the caller, as being in the local character encoding.
Treat all strings supplied as arguments, and return all strings to the caller, as being in UTF-8.

On UNIX-like systems, the local character encoding is assumed to be UTF-8, so no character encoding transformations are done.

On Windows, the local character encoding is the local ANSI code page.

If pcap_init() is not called, strings are treated as being in the local ANSI code page on Windows, pcap_lookupdev(3PCAP) will succeed if there is a device on which to capture, and pcap_create(3PCAP) makes an attempt to check whether the string passed as an argument is a UTF-16LE string - note that this attempt is unsafe, as it may run past the end of the string - to handle pcap_lookupdev() returning a UTF-16LE string. Programs that don't call pcap_init() should, on Windows, call pcap_wsockinit() to initialize Winsock; this is not necessary if pcap_init() is called, as pcap_init() will initialize Winsock itself on Windows.


pcap_init() returns 0 on success and PCAP_ERROR on failure. If PCAP_ERROR is returned, errbuf is filled in with an appropriate error message. errbuf is assumed to be able to hold at least PCAP_ERRBUF_SIZE chars.


This function became available in libpcap release 1.9.0. In previous releases, on Windows, all strings supplied as arguments, and all strings returned to the caller, are in the local character encoding.




This HTML man page was generated at 21:18:20 GMT, April 07, 2023 from a source man page in "The Tcpdump Group" git repositories using man2html and other tools.