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Neither the name of .\" the University nor the names of its contributors may be used to endorse .\" or promote products derived from this software without specific prior .\" written permission. .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED .\" WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. .\" .TH PCAP_FINDALLDEVS 3PCAP "29 April 2018" .SH NAME pcap_findalldevs, pcap_freealldevs \- get a list of capture devices, and free that list .SH SYNOPSIS .nf .ft B #include .ft .LP .nf .ft B char errbuf[PCAP_ERRBUF_SIZE]; .ft .LP .ft B int pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf); void pcap_freealldevs(pcap_if_t *alldevs); .ft .fi .SH DESCRIPTION .B pcap_findalldevs() constructs a list of network devices that can be opened with .B pcap_create() and .B pcap_activate() or with .BR pcap_open_live() . (Note that there may be network devices that cannot be opened by the process calling .BR pcap_findalldevs() , because, for example, that process does not have sufficient privileges to open them for capturing; if so, those devices will not appear on the list.) If .B pcap_findalldevs() succeeds, the pointer pointed to by .I alldevsp is set to point to the first element of the list, or to .B NULL if no devices were found (this is considered success). Each element of the list is of type .BR pcap_if_t , and has the following members: .RS .TP .B next if not .BR NULL , a pointer to the next element in the list; .B NULL for the last element of the list .TP .B name a pointer to a string giving a name for the device to pass to .B pcap_open_live() .TP .B description if not .BR NULL , a pointer to a string giving a human-readable description of the device .TP .B addresses a pointer to the first element of a list of network addresses for the device, or .B NULL if the device has no addresses .TP .B flags device flags: .RS .TP .B PCAP_IF_LOOPBACK set if the device is a loopback interface .TP .B PCAP_IF_UP set if the device is up .TP .B PCAP_IF_RUNNING set if the device is running .TP .B PCAP_IF_WIRELESS set if the device is a wireless interface; this includes IrDA as well as radio-based networks such as IEEE 802.15.4 and IEEE 802.11, so it doesn't just mean Wi-Fi .TP .B PCAP_IF_CONNECTION_STATUS a bitmask for an indication of whether the adapter is connected or not; for wireless interfaces, "connected" means "associated with a network" .TP The possible values for the connection status bits are: .TP .B PCAP_IF_CONNECTION_STATUS_UNKNOWN it's unknown whether the adapter is connected or not .TP .B PCAP_IF_CONNECTION_STATUS_CONNECTED the adapter is connected .TP .B PCAP_IF_CONNECTION_STATUS_DISCONNECTED the adapter is disconnected .TP .B PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE the notion of "connected" and "disconnected" don't apply to this interface; for example, it doesn't apply to a loopback device .RE .RE .PP Each element of the list of addresses is of type .BR pcap_addr_t , and has the following members: .RS .TP .B next if not .BR NULL , a pointer to the next element in the list; .B NULL for the last element of the list .TP .B addr a pointer to a .B "struct sockaddr" containing an address .TP .B netmask if not .BR NULL , a pointer to a .B "struct sockaddr" that contains the netmask corresponding to the address pointed to by .B addr .TP .B broadaddr if not .BR NULL , a pointer to a .B "struct sockaddr" that contains the broadcast address corresponding to the address pointed to by .BR addr ; may be null if the device doesn't support broadcasts .TP .B dstaddr if not .BR NULL , a pointer to a .B "struct sockaddr" that contains the destination address corresponding to the address pointed to by .BR addr ; may be null if the device isn't a point-to-point interface .RE .PP Note that the addresses in the list of addresses might be IPv4 addresses, IPv6 addresses, or some other type of addresses, so you must check the .B sa_family member of the .B "struct sockaddr" before interpreting the contents of the address; do not assume that the addresses are all IPv4 addresses, or even all IPv4 or IPv6 addresses. IPv4 addresses have the value .BR AF_INET , IPv6 addresses have the value .B AF_INET6 (which older operating systems that don't support IPv6 might not define), and other addresses have other values. Whether other addresses are returned, and what types they might have is platform-dependent. For IPv4 addresses, the .B "struct sockaddr" pointer can be interpreted as if it pointed to a .BR "struct sockaddr_in" ; for IPv6 addresses, it can be interpreted as if it pointed to a .BR "struct sockaddr_in6". .PP The list of devices must be freed with .BR pcap_freealldevs() , which frees the list pointed to by .IR alldevs . .SH RETURN VALUE .B pcap_findalldevs() returns 0 on success and \-1 on failure; as indicated, finding no devices is considered success, rather than failure, so 0 will be returned in that case. If \-1 is returned, .I errbuf is filled in with an appropriate error message. .I errbuf is assumed to be able to hold at least .B PCAP_ERRBUF_SIZE chars. .SH SEE ALSO pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP), pcap_open_live(3PCAP)