PCAP\_SET\_PROTOCOL\_LINUX(3PCAP) PCAP\_SET\_PROTOCOL\_LINUX(3PCAP) # [NAME](#NAME) pcap\_set\_protocol\_linux - set capture protocol for a not-yet-activated capture handle # [SYNOPSIS](#SYNOPSIS) ``` #include ``` ``` int pcap_set_protocol_linux(pcap_t *p, int protocol); ``` # [DESCRIPTION](#DESCRIPTION) On network interface devices on Linux, **pcap\_set\_protocol\_linux**() sets the protocol to be used in the [**socket**(2)](/man/os/libpcap/socket.2) call to create a capture socket when the handle is activated. The argument is a link-layer protocol value, such as the values in the **<linux/if\_ether.h>** header file, specified in host byte order. If *protocol* is non-zero, packets of that protocol will be captured when the handle is activated, otherwise, all packets will be captured. This function is only provided on Linux, and, if it is used on any device other than a network interface, it will have no effect. It should not be used in portable code; instead, a filter should be specified with [**pcap\_setfilter**(3PCAP)](/man/os/libpcap/pcap_setfilter.3PCAP). If a given network interface provides a standard link-layer header, with a standard packet type, but provides some packet types with a different socket-layer protocol type from the one in the link-layer header, that packet type cannot be filtered with a filter specified with **pcap\_setfilter**() but can be filtered by specifying the socket-layer protocol type using **pcap\_set\_protocol\_linux**(). # [RETURN VALUE](#RETURN_VALUE) **pcap\_set\_protocol\_linux**() returns **0** on success or **PCAP\_ERROR\_ACTIVATED** if called on a capture handle that has been activated. # [BACKWARD COMPATIBILITY](#BACKWARD_COMPATIBILITY) This function became available in libpcap release 1.9.0. # [SEE ALSO](#SEE_ALSO) [**pcap**(3PCAP)](/man/os/libpcap/pcap.3PCAP), [**pcap\_create**(3PCAP)](/man/os/libpcap/pcap_create.3PCAP), [**pcap\_activate**(3PCAP)](/man/os/libpcap/pcap_activate.3PCAP) 22 August 2018 --- Document: pcap_set_protocol_linux(3pcap) from libpcap 1.11.0-r0 (Chainguard OS) Source: https://github.com/the-tcpdump-group/libpcap.git