1.\" Copyright 1996 Massachusetts Institute of Technology 2.\" 3.\" Permission to use, copy, modify, and distribute this software and 4.\" its documentation for any purpose and without fee is hereby 5.\" granted, provided that both the above copyright notice and this 6.\" permission notice appear in all copies, that both the above 7.\" copyright notice and this permission notice appear in all 8.\" supporting documentation, and that the name of M.I.T. not be used 9.\" in advertising or publicity pertaining to distribution of the 10.\" software without specific, written prior permission. M.I.T. makes 11.\" no representations about the suitability of this software for any 12.\" purpose. It is provided "as is" without express or implied 13.\" warranty. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY M.I.T. ``AS IS''. M.I.T. DISCLAIMS 16.\" ALL EXPRESS OR IMPLIED WARRANTIES WITH REGARD TO THIS SOFTWARE, 17.\" INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF 18.\" MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT 19.\" SHALL M.I.T. BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 21.\" LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 22.\" USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 23.\" ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25.\" OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd November 15, 1996 31.Dt IFMIB 4 32.Os 33.Sh NAME 34.Nm ifmib 35.Nd Management Information Base for network interfaces 36.Sh SYNOPSIS 37.Fd #include <sys/types.h> 38.Fd #include <sys/socket.h> 39.Fd #include <sys/sysctl.h> 40.Fd #include <sys/time.h> 41.Fd #include <net/if.h> 42.Fd #include <net/if_mib.h> 43.Sh DESCRIPTION 44The 45.Nm 46facility is an application of the 47.Xr sysctl 3 48interface to provide management information about network interfaces 49to client applications such as 50.Xr netstat 1 , 51.Xr slstat 8 , 52and 53.Tn SNMP 54management agents. This information is structured as a table, where 55each row in the table represents a logical network interface (either a 56hardware device or a software pseudo-device like 57.Xr lo 4 ) . 58There are two columns in the table, each containing a single 59structure: one column contains generic information relevant to all 60interfaces, and the other contains information specific to the 61particular class of interface. (Generally the latter will implement 62the 63.Tn SNMP 64.Tn MIB 65defined for that particular interface class, if one exists and can be 66implemented in the kernel.) 67.Pp 68The 69.Nm 70facility is accessed via the 71.Dq Li net.link.generic 72branch of the 73.Xr sysctl 3 74MIB. The manifest constants for each level in the 75.Xr sysctl 3 76.Ar name 77are defined in 78.Aq Pa net/if_mib.h . 79A count of interfaces (and thus rows in the table) is given by 80.Dq Li net.link.generic.system.ifcount 81(or, using the manifest constants, 82.Dv CTL_NET , 83.Dv PF_LINK , 84.Dv NETLINK_GENERIC , 85.Dv IFMIB_SYSTEM , 86.Dv IFMIB_IFCOUNT ) . 87A management application searching for a particular interface should 88start with row 1 and continue through the table row-by-row until the 89desired interface is found, or the interface count is reached. 90.Pp 91The generic interface information, common to all interfaces, 92can be accessed via the following procedure: 93.Bd -literal -offset indent 94int 95get_ifmib_general(int row, struct ifmibdata *ifmd) 96{ 97 int name[6]; 98 99 name[0] = CTL_NET; 100 name[1] = PF_LINK; 101 name[2] = NETLINK_GENERIC; 102 name[3] = IFMIB_IFDATA; 103 name[4] = row; 104 name[5] = IFDATA_GENERAL; 105 106 return sysctl(name, 6, ifmd, sizeof *ifmd, (void *)0, 0); 107} 108.Ed 109.Pp 110The fields in 111.Li struct ifmibdata 112are as follows: 113.Bl -tag -width "ifmd_snd_drops" 114.It Li ifmd_name 115.Pq Li "char []" 116the name of the interface, including the unit number 117.It Li ifmd_pcount 118.Pq Li int 119the number of promiscuous listeners 120.It Li ifmd_flags 121.Pq Li int 122the interface's flags (defined in 123.Aq Pa net/if.h ) 124.It Li ifmd_snd_len 125.Pq Li int 126the current instantaneous length of the send queue 127.It Li ifmd_snd_drops 128.Pq Li int 129the number of packets dropped at this interface because the send queue 130was full 131.It Li ifmd_data 132.Pq Li struct if_data 133more information from a structure defined in 134.Aq Pa net/if.h 135(see 136.Xr if_data 9 ) 137.El 138.Pp 139Class-specific information can be retrieved by examining the 140.Dv IFDATA_LINKSPECIFIC 141column instead. Note that the form and length of the structure will 142depend on the class of interface. For 143.Dv IFT_ETHER , 144.Dv IFT_ISO88023 , 145and 146.Dv IFT_STARLAN 147interfaces, the structure is called 148.Dq Li struct ifmib_iso_8802_3 149(defined in 150.Aq Pa net/if_mib.h ) , 151and implements a superset of the 152.Tn "RFC 1650" 153MIB for Ethernet-like networks. 154.\" This will eventually be defined in an ethermib(4) page. 155For 156.Dv IFT_SLIP , 157the structure is a 158.Dq Li struct sl_softc 159.Pq Aq Pa net/if_slvar.h . 160.Sh SEE ALSO 161.Xr sysctl 3 , 162.Xr intro 4 , 163.Xr ifnet 9 164.\" .Xr ethermib 4 , 165.Rs 166.%T "Definitions of Managed Objects for the Ethernet-like Interface Types Using SMIv2" 167.%A F. Kastenholz 168.%D August 1994 169.%O RFC 1650 170.Re 171.Sh BUGS 172Many Ethernet-like interfaces do not yet support the Ethernet MIB; 173the interfaces known to support it include 174.Xr ed 4 175and 176.Xr de 4 . 177Regardless, all interfaces automatically support the generic MIB. 178.Sh HISTORY 179The 180.Nm 181interface first appeared in 182.Fx 2.2 . 183