if(7P)
NAME
if_tcp, if - general properties of Internet Protocol network
interfaces
DESCRIPTION
A network interface is a device for sending and receiving
packets on a network. It is usually a hardware device,
although it can be implemented in software. Network inter-
faces used by the Internet Protocol (IPv4 or IPv6) must be
STREAMS devices conforming to the Datalink Provider Inter-
face (DLPI). See dlpi(7P).
APPLICATION PROGRAMMING INTERFACE
An interface becomes available to IP when it is opened and
the IP module is pushed onto the stream with the I_PUSH
ioctl(2) command (see streamio(7I)), and the SIOCSLIFNAME
ioctl(2) is issued to specify the name of the interface and
whether it is IPv4 or IPv6. This may be initiated by the
kernel at boot time or by a user program after the system is
running. Each interface must be assigned an IP address with
the SIOCSLIFADDR ioctl() before it can be used. On inter-
faces where the network-to-link layer address mapping is
static, only the network number is taken from the ioctl()
request; the remainder is found in a hardware specific
manner. On interfaces which provide dynamic network-to-link
layer address mapping facilities (for example, 10Mb/s Ether-
nets using arp(7P)), the entire address specified in the
ioctl() is used. A routing table entry for destinations on
the network of the interface is installed automatically when
an interface's address is set.
IOCTLS
The following ioctl() calls may be used to manipulate IP
network interfaces. Unless specified otherwise, the request
takes an lifreq structure as its parameter. This structure
has the form:
/* Interface request structure used for socket ioctls. All */
/* interface ioctls must have parameter definitions which */
/* begin with ifr_name. The remainder may be interface specific. */
struct lifreq {
#define LIFNAMSIZ 32
char lfr_name[LIFNAMSIZ]; /* if name, for example "le1" */
union {
int lifru_addrlen; /* for subnet/token etc */
uint_t lifru_ppa; /* SIOCSLIFNAME */
} lifr_lifru1;
union {
struct sockaddr_storage lifru_addr;
struct sockaddr_storage lifru_dstaddr;
struct sockaddr_storage lifru_broadaddr;
struct sockaddr_storage lifru_token; /* With lifr_addrlen */
struct sockaddr_storage lifru_subnet; /* With lifr_addrlen */
int lifru_index; /* interface index */
uint64_t lifru_flags; /* SIOC?LIFFLAGS */
int lifru_metric;
uint_t lifru_mtu;
char lifru_data[1]; /* intfce.dep. data/
char lifru_enaddr[6];
int lif_muxid[2]; /* mux id's for arp and ip */
struct lif_nd_req lifru_nd_req;
struct lif_ifinfo_req lifru_ifinfo_req;
} lifr_lifru;
#define lifr_addrlen lifr_lifru1.lifru_addrlen
#define lifr_ppa lifr_lifru1.lifru_ppa /* Driver's ppa */
#define lifr_addr lifr_lifru.lifru_addr /* address */
#define lifr_dstaddr lifr_lifru.lifru_dstaddr
#define lifr_broadaddr lifr_lifru.lifru_broadaddr /* broadcast address */
#define lifr_token lifr_lifru.lifru_token /* address token */
#define lifr_subnet lifr_lifru.lifru_subnet /* subnet prefix */
#define lifr_index lifr_lifru.lifru_index /* interface index */
#define lifr_flags lifr_lifru.lifru_flags /* flags */
#define lifr_metric lifr_lifru.lifru_metric /* metric */
#define lifr_mtu lifr_lifru.lifru_mtu /* mtu */
#define lifr_data lifr_lifru.lifru_data
#define lifr_enaddr lifr_lifru.lifru_enaddr /* ethernet address */
#define lifr_index lifr_lifru.lifru_index /* interface index */
#define lifr_ip_muxid lifr_lifru.lif_muxid[0]
#define lifr_arp_muxid lifr_lifru.lif_muxid[1]
#define lifr_nd lifr_lifru.lifru_nd_req /* SIOCLIF*ND */
#define lifr_ifinfo lifr_lifru.lifru_ifinfo_req /* SIOC[GS]LIFLNKINFO */
};
SIOCSLIFADDR
Set interface address. Following the address assign-
ment, the "initialization" routine for the interface
is called.
SIOCGLIFADDR
Get interface address.
SIOCSLIFDSTADDR
Set point to point address for interface.
SIOCGLIFDSTADDR
Get point to point address for interface.
SIOCSLIFFLAGS
Set interface flags field. If the interface is marked
down, any processes currently routing packets through
the interface are notified.
SIOCGLIFFLAGS
Get interface flags.
SIOCGLIFCONF
Get interface configuration list. This request takes
an lifconf structure (see below) as a value-result
parameter. The lifc_len field should be initially set
to the size of the buffer pointed to by lifc_buf. On
return it will contain the length, in bytes, of the
configuration list. The lifc_family field should be
set to AF_UNSPEC to retrieve both AF_INET and AF_INET6
interfaces. The lifc_flags field should be initially
set to zero.
SIOCGLIFNUM
Get number of interfaces. This request returns an
integer which is the number of interface descriptions
(struct lifreq) that will be returned by the
SIOCGLIFCONF ioctl; that is, it gives an indication of
how large lifc_len has to be. This request takes an
lifnum structure (see below) as a value-result parame-
ter. The lifn_family field should be set to AF_UNSPEC
to count both AF_INET and AF_INET6 interfaces. The
lifn_flags field should be initially set to zero.
SIOCSLIFMTU
Set the maximum transmission unit (MTU) size for
interface. Place the result of this request in
lifru_mtu field. The MTU can not exceed the physical
MTU limitation (which is reported in the DLPI
DL_INFO_ACK message).
SIOCGLIFMTU
Get the maximum transmission unit size for interface.
Place the result of this request in ifru_mtu field.
SIOCSLIFMETRIC
Set the metric associated with the interface. The
metric is used by routine daemons such as
in.routed(1M).
SIOCGLIFMETRIC
Get the metric associated with the interface.
SIOCGLIFMUXID
Get the ip and arp muxid associated with the inter-
face.
SIOCSLIFMUXID
Set the ip and arp muxid associated with the inter-
face.
SIOCGLIFINDEX
Get the interface index associated with the interface.
SIOCSLIFINDEX
Set the interface index associated with the interface.
SIOCLIFADDIF
Add a new logical interface on a physical interface
using an unused logical unit number.
SIOCLIFREMOVEIF
Remove a logical interface by specifying its IP
address or logical interface name.
SIOCSLIFTOKEN
Set the address token used to form IPv6 link-local
addresses and for stateless address autoconfiguration.
SIOCGLIFTOKEN
Get the address token used to form IPv6 link-local
addresses and for stateless address autoconfiguration.
SIOCSLIFSUBNET
Set the subnet prefix associated with the interface.
SIOCGLIFSUBNET
Get the subnet prefix associated with the interface.
SIOCSLIFLNKINFO
Set link specific parameters for the interface.
SIOCGLIFLNKINFO
Get link specific parameters for the interface.
SIOCLIFDELND
Delete a neighbor cache entry for IPv6.
SIOCLIFGETND
Get a neighbor cache entry for IPv6.
SIOCLIFSETND
Set a neighbor cache entry for IPv6.
SIOCTMYADDR
Test if the address is assigned to this node. This
request takes an sioc_addrreq structure (see below) as
a value-result parameter. The sa_addr field should be
set to the address to test. The sa_res field will con-
tain a non-zero value if the address is assigned to
this node.
SIOCTONLINK
Test if the address is directly reachable, for
example, that it can be reached without going through
a router. This request takes an sioc_addrreq structure
(see below) as a value-result parameter. The sa_addr
field should be set to the address to test. The sa_res
field will contain a non-zero value if the address is
onlink.
SIOCTMYSITE
Test if the address is part of the same site as this
node. This request takes an sioc_addrreq structure
(see below) as a value-result parameter. The sa_addr
field should be set to the address to test. The sa_res
field will contain a non-zero value if the address is
in the same site.
The lifconf structure has the form:
/*
* Structure used in SIOCGLIFCONF request.
* Used to retrieve interface configuration
* for machine (useful for programs which
* must know all networks accessible).
*/
struct lifconf {
sa_family_t lifc_family;
int lifc_flags; /* request specific interfaces */
int lifc_len; /* size of associated buffer */
union {
caddr_t lifcu_buf;
struct ifreq *lifcu_req;
} lifc_lifcu;
#define lifc_buf lifc_lifcu.lifcu_buf /* buffer address */
#define lifc_req lifc_lifcu.lifcu_req /* array of structures returned */
};
The sioc_addrreq structure has the form:
/* Structure used in SIOCGLIFNUM request. */
struct lifnum {
sa_family_t lifn_family;
int lifn_flags; /* request specific interfaces */
int lifn_count; /* Result */
};
/*
* Argument structure for SIOCT* address testing ioctls.
*/
struct sioc_addrreq {
struct sockaddr_storage sa_addr; /* Address to test */
int sa_res; /* Result - 0/1 */
};
The following ioctl() calls are maintained for compatibility
but only apply to IPv4 network interfaces, since the data
structures are to small to hold an IPv6 address. Unless
specified otherwise, the request takes an ifreq structure as
its parameter. This structure has the form:
/* Interface request structure used for socket ioctls. All */
/* interface ioctls must have parameter definitions which */
/* begin with ifr_name. The remainder may be interface specific. */
struct ifreq {
#define IFNAMSIZ 16
char ifr_name[IFNAMSIZ]; /* if name, for example */
/* "le1" */
union {
struct sockaddr ifru_addr;
struct sockaddr ifru_dstaddr;
char ifru_oname[IFNAMSIZ]; /* other if name */
struct sockaddr ifru_broadaddr;
short ifru_flags;
int ifru_metric;
char ifru_data[1]; /* intfce. depen. data */
char ifru_enaddr[6];
int if_muxid[2]; /* mux id's for arp and ip */
int ifru_index; /* interface index */
} ifr_ifru;
#define ifr_addr ifr_ifru.ifru_addr /* address */
#define ifr_dstaddr ifr_ifru.ifru_dstaddr /* other end of p-to-p link */
#define ifr_oname ifr_ifru.ifru_oname /* other if name */
#define ifr_broadaddr ifr_ifru.ifru_broadaddr /* broadcast address */
#define ifr_flags ifr_ifru.ifru_flags /* flags */
#define ifr_index ifr_ifru.ifru_index /* interface index */
#define ifr_metric ifr_ifru.ifru_metric /* metric */
#define ifr_data ifr_ifru.ifru_data /* for use by interface */
#define ifr_enaddr ifr_ifru.ifru_enaddr a/* ethernet address */
};
SIOCSIFADDR
Set interface address. Following the address assign-
ment, the "initialization" routine for the interface
is called.
SIOCGIFADDR
Get interface address.
SIOCSIFDSTADDR
Set point to point address for interface.
SIOCGIFDSTADDR
Get point to point address for interface.
SIOCSIFFLAGS
Set interface flags field. If the interface is marked
down, any processes currently routing packets through
the interface are notified.
SIOCGIFFLAGS
Get interface flags.
SIOCGIFCONF
Get interface configuration list. This request takes
an ifconf structure (see below) as a value-result
parameter. The ifc_len field should be initially set
to the size of the buffer pointed to by ifc_buf. On
return it will contain the length, in bytes, of the
configuration list.
SIOCGIFNUM
Get number of interfaces. This request returns an
integer which is the number of interface descriptions
(struct ifreq) that will be returned by the
SIOCGIFCONF ioctl; that is, it gives an indication of
how large ifc_len has to be.
SIOCSIFMTU
Set the maximum transmission unit (MTU) size for
interface. Place the result of this request in
ifru_metric field. The MTU has to be smaller than phy-
sical MTU limitation (which is reported in the DLPI
DL_INFO_ACK message).
SIOCGIFMTU
Get the maximum transmission unit size for interface.
Place the result of this request in ifru_metric field.
SIOCSIFMETRIC
Set the metric associated with the interface. The
metric is used by routine daemons such as
in.routed(1M).
SIOCGIFMETRIC
Get the metric associated with the interface.
SIOCGIFMUXID
Get the ip and arp muxid associated with the inter-
face.
SIOCSIFMUXID
Set the ip and arp muxid associated with the inter-
face.
SIOCGIFINDEX
Get the interface index associated with the interface.
SIOCSIFINDEX
Set the interface index associated with the interface.
The ifconf structure has the form:
/*
* Structure used in SIOCGIFCONF request.
* Used to retrieve interface configuration
* for machine (useful for programs which
* must know all networks accessible).
*/
struct ifconf {
int ifc_len; /* size of associated buffer */
union {
caddr_t ifcu_buf;
struct ifreq *ifcu_req;
} ifc_ifcu;
#define ifc_buf ifc_ifcu.ifcu_buf /* buffer address */
#define ifc_req ifc_ifcu.ifcu_req /* array of structures returned */
};
ERRORS
EPERM The effective user id of the calling process in not
superuser.
ENXIO The lifr_name member of the lifreq structure con-
tains an invalid value.
EBADADDR
Wrong address family or malformed address.
EBUSY For SIOCSLIFFLAGS, this error is returned when the
order of bringing the primary/physical interface (for
example, le0) and a secondary/logical interface asso-
ciated with the same physical interface (for example,
le0:1) up or down is violated.
The physical interface must be configured up first
and cannot be configured down until all the
corresponding logical interfaces have been configured
down.
EINVAL
For SIOCGLIFCONF, this error is returned when the
size of the buffer pointed to by the lifc_buf member
of the lifconf structure is too small.
For SIOCSLIFMTU, this error is returned when the
requested MTU size is invalid. This error indicates
the MTU size is greater than the MTU size supported by
the DLPI provider or less than 68 (for IPv4 ) or
less than 1200 (for IPv6 ).
EEXIST
For SIOCLIFADDIF, this error is returned if the
lifr_name member in the lifreq structure has a logical
interface name and the specified logical interface
already exists.
SEE ALSO
ifconfig(1M), in.routed(1M), ioctl(2), streamio(7I),
arp(7P), dlpi(7P), ip(7P), ip6(7P)
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