1PCAP_FINDALLDEVS(3PCAP) PCAP_FINDALLDEVS(3PCAP)
2
6 pcap_findalldevs, pcap_freealldevs - get a list of capture devices, and
7 free that list
8
10 #include <pcap/pcap.h>
11 char errbuf[PCAP_ERRBUF_SIZE];
13 int pcap_findalldevs(pcap_if_t **alldevsp, char *errbuf);
15 void pcap_freealldevs(pcap_if_t *alldevs);
16
18 pcap_findalldevs() constructs a list of network devices that can be
19 opened with pcap_create() and pcap_activate() or with pcap_open_live().
20 (Note that there may be network devices that cannot be opened by the
21 process calling pcap_findalldevs(), because, for example, that process
22 does not have sufficient privileges to open them for capturing; if so,
23 those devices will not appear on the list.) If pcap_findalldevs() suc‐
24 ceeds, the pointer pointed to by alldevsp is set to point to the first
25 element of the list, or to NULL if no devices were found (this is con‐
26 sidered success). Each element of the list is of type pcap_if_t, and
27 has the following members:
28 next if not NULL, a pointer to the next element in the list;
30 NULL for the last element of the list
31 name a pointer to a string giving a name for the device to
33 pass to pcap_open_live()
34 description
36 if not NULL, a pointer to a string giving a human-read‐
37 able description of the device
38 addresses
40 a pointer to the first element of a list of network
41 addresses for the device, or NULL if the device has no
42 addresses
43 flags device flags:
45 PCAP_IF_LOOPBACK
47 set if the device is a loopback interface
48 PCAP_IF_UP
50 set if the device is up
51 PCAP_IF_RUNNING
53 set if the device is running
54 PCAP_IF_WIRELESS
56 set if the device is a wireless interface; this
57 includes IrDA as well as radio-based networks such
58 as IEEE 802.15.4 and IEEE 802.11, so it doesn't
59 just mean Wi-Fi
60 PCAP_IF_CONNECTION_STATUS
62 a bitmask for an indication of whether the adapter
63 is connected or not; for wireless interfaces,
64 "connected" means "associated with a network"
65 The possible values for the connection status bits are:
67 PCAP_IF_CONNECTION_STATUS_UNKNOWN
69 it's unknown whether the adapter is connected or
70 not
71 PCAP_IF_CONNECTION_STATUS_CONNECTED
73 the adapter is connected
74 PCAP_IF_CONNECTION_STATUS_DISCONNECTED
76 the adapter is disconnected
77 PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE
79 the notion of "connected" and "disconnected" don't
80 apply to this interface; for example, it doesn't
81 apply to a loopback device
82 Each element of the list of addresses is of type pcap_addr_t, and has
84 the following members:
85 next if not NULL, a pointer to the next element in the list;
87 NULL for the last element of the list
88 addr a pointer to a struct sockaddr containing an address
90 netmask
92 if not NULL, a pointer to a struct sockaddr that contains
93 the netmask corresponding to the address pointed to by
94 addr
95 broadaddr
97 if not NULL, a pointer to a struct sockaddr that contains
98 the broadcast address corresponding to the address
99 pointed to by addr; may be null if the device doesn't
100 support broadcasts
101 dstaddr
103 if not NULL, a pointer to a struct sockaddr that contains
104 the destination address corresponding to the address
105 pointed to by addr; may be null if the device isn't a
106 point-to-point interface
107 Note that the addresses in the list of addresses might be IPv4
109 addresses, IPv6 addresses, or some other type of addresses, so you must
110 check the sa_family member of the struct sockaddr before interpreting
111 the contents of the address; do not assume that the addresses are all
112 IPv4 addresses, or even all IPv4 or IPv6 addresses. IPv4 addresses
113 have the value AF_INET, IPv6 addresses have the value AF_INET6 (which
114 older operating systems that don't support IPv6 might not define), and
115 other addresses have other values. Whether other addresses are
116 returned, and what types they might have is platform-dependent. For
117 IPv4 addresses, the struct sockaddr pointer can be interpreted as if it
118 pointed to a struct sockaddr_in; for IPv6 addresses, it can be inter‐
119 preted as if it pointed to a struct sockaddr_in6.
120 The list of devices must be freed with pcap_freealldevs(), which frees
122 the list pointed to by alldevs.
123
125 pcap_findalldevs() returns 0 on success and -1 on failure; as indi‐
126 cated, finding no devices is considered success, rather than failure,
127 so 0 will be returned in that case. If -1 is returned, errbuf is
128 filled in with an appropriate error message. errbuf is assumed to be
129 able to hold at least PCAP_ERRBUF_SIZE chars.
130
132 pcap(3PCAP), pcap_create(3PCAP), pcap_activate(3PCAP),
133 pcap_open_live(3PCAP)
134 29 April 2018 PCAP_FINDALLDEVS(3PCAP)