pcap_set_immediate_mode() sets whether immediate mode should be set
on a capture handle when the handle is activated. In immediate mode,
packets are always delivered as soon as they arrive, with no
buffering. If immediate_mode is non-zero, immediate mode will be
set, otherwise it will not be set.
This function became available in libpcap release 1.5.0. In previous
releases, if immediate delivery of packets is required:
on FreeBSD, NetBSD, OpenBSD, DragonFly BSD, macOS, and Solaris
11, immediate mode must be turned on with a BIOCIMMEDIATEioctl(2), as documented in bpf(4), on the descriptor returned
by pcap_fileno(3PCAP), after pcap_activate(3PCAP) is called;
on Solaris 10 and earlier versions of Solaris, immediate mode
must be turned on by using a read timeout of 0 when opening
the device (this will not provide immediate delivery of
packets on other platforms, so don't assume it's sufficient);
on Digital UNIX/Tru64 UNIX, immediate mode must be turned on
by doing a BIOCMBIC ioctl, as documented in packetfilter(7),
to clear the ENBATCH flag on the descriptor returned by
pcap_fileno(3PCAP), after pcap_activate(3PCAP) is called;
on Windows, immediate mode must be turned on by calling
pcap_setmintocopy() with a size of 0.
On Linux, with previous releases of libpcap, capture devices are
always in immediate mode; however, in 1.5.0 and later, they are, by
default, not in immediate mode, so if pcap_set_immediate_mode() is
available, it should be used.
On other platforms, capture devices are always in immediate mode.
This page is part of the libpcap (packet capture library) project.
Information about the project can be found at
⟨http://www.tcpdump.org/⟩. If you have a bug report for this manual
page, see ⟨http://www.tcpdump.org/#patches⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/the-tcpdump-group/libpcap.git⟩ on 2020-06-09.
(At that time, the date of the most recent commit that was found in
the repository was 2020-06-07.) If you discover any rendering prob‐
lems in this HTML version of the page, or you believe there is a bet‐
ter or more up-to-date source for the page, or you have corrections
or improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to email@example.com
23 August 2018 PCAP_SET_IMMEDIATE_MODE(3PCAP)