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.In sys/types.h 38.In sys/socket.h 39.In sys/sysctl.h 40.In sys/time.h 41.In net/if.h 42.In 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 . 79The index of the last row 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. 90Note that the table may be sparse, i.e. a given row may not exist, 91indicated by an 92.Va errno 93of 94.Er ENOENT . 95Such an error should be ignored, and the next row should be checked. 96.Pp 97The generic interface information, common to all interfaces, 98can be accessed via the following procedure: 99.Bd -literal -offset indent 100int 101get_ifmib_general(int row, struct ifmibdata *ifmd) 102{ 103 int name[6]; 104 105 name[0] = CTL_NET; 106 name[1] = PF_LINK; 107 name[2] = NETLINK_GENERIC; 108 name[3] = IFMIB_IFDATA; 109 name[4] = row; 110 name[5] = IFDATA_GENERAL; 111 112 return sysctl(name, 6, ifmd, sizeof *ifmd, (void *)0, 0); 113} 114.Ed 115.Pp 116The fields in 117.Li struct ifmibdata 118are as follows: 119.Bl -tag -width "ifmd_snd_drops" 120.It Li ifmd_name 121.Pq Li "char []" 122the name of the interface, including the unit number 123.It Li ifmd_pcount 124.Pq Li int 125the number of promiscuous listeners 126.It Li ifmd_flags 127.Pq Li int 128the interface's flags (defined in 129.Aq Pa net/if.h ) 130.It Li ifmd_snd_len 131.Pq Li int 132the current instantaneous length of the send queue 133.It Li ifmd_snd_drops 134.Pq Li int 135the number of packets dropped at this interface because the send queue 136was full 137.It Li ifmd_data 138.Pq Li struct if_data 139more information from a structure defined in 140.Aq Pa net/if.h 141(see 142.Xr if_data 9 ) 143.El 144.Pp 145Class-specific information can be retrieved by examining the 146.Dv IFDATA_LINKSPECIFIC 147column instead. Note that the form and length of the structure will 148depend on the class of interface. For 149.Dv IFT_ETHER , 150.Dv IFT_ISO88023 , 151and 152.Dv IFT_STARLAN 153interfaces, the structure is called 154.Dq Li struct ifmib_iso_8802_3 155(defined in 156.Aq Pa net/if_mib.h ) , 157and implements a superset of the 158.Tn "RFC 1650" 159MIB for Ethernet-like networks. 160.\" This will eventually be defined in an ethermib(4) page. 161For 162.Dv IFT_SLIP , 163the structure is a 164.Dq Li struct sl_softc 165.Pq Aq Pa net/if_slvar.h . 166.Sh SEE ALSO 167.Xr sysctl 3 , 168.Xr intro 4 , 169.Xr ifnet 9 170.\" .Xr ethermib 4 , 171.Rs 172.%T "Definitions of Managed Objects for the Ethernet-like Interface Types Using SMIv2" 173.%A F. Kastenholz 174.%D August 1994 175.%O RFC 1650 176.Re 177.Sh BUGS 178Many Ethernet-like interfaces do not yet support the Ethernet MIB; 179the interfaces known to support it include 180.Xr ed 4 181and 182.Xr de 4 . 183Regardless, all interfaces automatically support the generic MIB. 184.Sh HISTORY 185The 186.Nm 187interface first appeared in 188.Fx 2.2 . 189