--- name: "pcap_freealldevs" section: "3" platform: "freebsd" package: "base" version: "16.0-CURRENT-20261027-61c70dc16a79" release: "FreeBSD 16.0-CURRENT (2026-10-27)" platforms: ["freebsd"] url: "https://new.carta.tech/pcap_findalldevs" --- # pcap\_freealldevs(3) get a list of capture devices, and free that list Part of [pcap\_findalldevs(3)](/pcap_findalldevs/3.md). ## NAME pcap\_findalldevs, pcap\_freealldevs - get a list of capture devices, and free that list ## SYNOPSIS ``` #include ``` ``` char errbuf[PCAP_ERRBUF_SIZE]; ``` **int pcap\_findalldevs(pcap\_if\_t \*\*alldevsp, char \*errbuf);** **void pcap\_freealldevs(pcap\_if\_t \*alldevs);** ## DESCRIPTION **pcap\_findalldevs**() constructs a list of network devices that can be opened with [**pcap\_create**(3)](/pcap_create/3.md) and [**pcap\_activate**(3)](/pcap_activate/3.md) or with [**pcap\_open\_live**(3)](/pcap_open_live/3.md). (Note that there may be network devices that cannot be opened by the process calling **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.) *alldevsp* is a pointer to a **pcap\_if\_t \***; *errbuf* is a buffer large enough to hold at least **PCAP\_ERRBUF\_SIZE** chars. If **pcap\_findalldevs**() succeeds, the pointer pointed to by *alldevsp* is set to point to the first element of the list, or to **NULL** if no devices were found (this is considered success). Each element of the list is of type **pcap\_if\_t**, and has the following members: - **next** if not **NULL**, a pointer to the next element in the list; **NULL** for the last element of the list - **name** a pointer to a string giving a name for the device to pass to **pcap\_open\_live**() - **description** if not **NULL**, a pointer to a string giving a human-readable description of the device - **addresses** a pointer to the first element of a list of network addresses for the device, or **NULL** if the device has no addresses - **flags** device flags: - **PCAP\_IF\_LOOPBACK** set if the device is a loopback interface - **PCAP\_IF\_UP** set if the device is up - **PCAP\_IF\_RUNNING** set if the device is running - **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 - **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" - The possible values for the connection status bits are: - **PCAP\_IF\_CONNECTION\_STATUS\_UNKNOWN** it's unknown whether the adapter is connected or not - **PCAP\_IF\_CONNECTION\_STATUS\_CONNECTED** the adapter is connected - **PCAP\_IF\_CONNECTION\_STATUS\_DISCONNECTED** the adapter is disconnected - **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 Each element of the list of addresses is of type **pcap\_addr\_t**, and has the following members: - **next** if not **NULL**, a pointer to the next element in the list; **NULL** for the last element of the list - **addr** a pointer to a **struct sockaddr** containing an address - **netmask** if not **NULL**, a pointer to a **struct sockaddr** that contains the netmask corresponding to the address pointed to by **addr** - **broadaddr** if not **NULL**, a pointer to a **struct sockaddr** that contains the broadcast address corresponding to the address pointed to by **addr**; may be **NULL** if the device doesn't support broadcasts - **dstaddr** if not **NULL**, a pointer to a **struct sockaddr** that contains the destination address corresponding to the address pointed to by **addr**; may be **NULL** if the device isn't a point-to-point interface 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 **sa\_family** member of the **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 **AF\_INET**, IPv6 addresses have the value **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. Namely, link-layer addresses, such as Ethernet MAC addresses, have the value **AF\_PACKET** (on Linux) or **AF\_LINK** (on AIX, FreeBSD, Haiku, illumos, macOS, NetBSD and OpenBSD) or are not returned at all (on GNU/Hurd and Solaris). For IPv4 addresses, the **struct sockaddr** pointer can be interpreted as if it pointed to a **struct sockaddr\_in**; for IPv6 addresses, it can be interpreted as if it pointed to a **struct sockaddr\_in6**. For link-layer addresses, it can be interpreted as if it pointed to a **struct sockaddr\_ll** (for **AF\_PACKET**) or a **struct sockaddr\_dl** (for **AF\_LINK**). The list of devices must be freed with [**pcap\_freealldevs**(3)](/pcap_freealldevs/3.md), which frees the list pointed to by *alldevs*. ## RETURN VALUE **pcap\_findalldevs**() returns **0** on success and **PCAP\_ERROR** on failure; as indicated, finding no devices is considered success, rather than failure, so **0** will be returned in that case. If **PCAP\_ERROR** is returned, *errbuf* is filled in with an appropriate error message, and the pointer pointed to by *alldevsp* is set to **NULL**. ## BACKWARD COMPATIBILITY The **PCAP\_IF\_UP** and **PCAP\_IF\_RUNNING** constants became available in libpcap release 1.6.1. The **PCAP\_IF\_WIRELESS**, **PCAP\_IF\_CONNECTION\_STATUS**, **PCAP\_IF\_CONNECTION\_STATUS\_UNKNOWN**, **PCAP\_IF\_CONNECTION\_STATUS\_CONNECTED**, **PCAP\_IF\_CONNECTION\_STATUS\_DISCONNECTED**, and **PCAP\_IF\_CONNECTION\_STATUS\_NOT\_APPLICABLE** constants became available in libpcap release 1.9.0. ## SEE ALSO [**pcap**(3)](/pcap/3.md)