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.\" $Id$ 29.\" 30.Dd November 15, 1996 31.Dt IFMIB 4 32.Os FreeBSD 2.2 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 <net/if.h> 41.Fd #include <net/if_mib.h> 42.Sh DESCRIPTION 43The 44.Nm ifmib 45facility is an application of the 46.Xr sysctl 3 47interface to provide management information about network interfaces 48to client applications such as 49.Xr netstat 1 , 50.Xr slstat 8 , 51and 52.Tn SNMP 53management agents. This information is structured as a table, where 54each row in the table represents a logical network interface (either a 55hardware device or a software pseudo-device like 56.Xr lo 4 ) . 57There are two columns in the table, each containing a single 58structure: one column contains generic information relevant to all 59interfaces, and the other contains information specific to the 60particular class of interface. (Generally the latter will implement 61the 62.Tn SNMP 63.Tn MIB 64defined for that particular interface class, if one exists and can be 65implemented in the kernel.) 66.Pp 67The 68.Nm 69facility is accessed via the 70.Dq Li net.link.generic 71branch of the 72.Xr sysctl 3 73MIB. The manifest constants for each level in the 74.Xr sysctl 3 75.Ar name 76are defined in 77.Aq Pa net/if_mib.h . 78A count of interfaces (and thus rows in the table) is given by 79.Dq Li net.link.generic.system.ifcount 80(or, using the manifest constants, 81.Dv CTL_NET , 82.Dv PF_LINK , 83.Dv NETLINK_GENERIC , 84.Dv IFMIB_SYSTEM , 85.Dv IFMIB_IFCOUNT ) . 86A management application searching for a particular interface should 87start with row 1 and continue through the table row-by-row until the 88desired interface is found, or the interface count is reached. 89.Pp 90The generic interface information, common to all interfaces, 91can be accessed via the following procedure: 92.Bd -literal -offset indent 93int 94get_ifmib_general(int row, struct ifmibdata *ifmd) 95{ 96 int name[6]; 97 98 name[0] = CTL_NET; 99 name[1] = PF_LINK; 100 name[2] = NETLINK_GENERIC; 101 name[3] = IFMIB_IFDATA; 102 name[4] = row; 103 name[5] = IFDATA_GENERAL; 104 105 return sysctl(name, 6, ifmd, sizeof *ifmd, (void *)0, 0); 106} 107.Ed 108.Pp 109The fields in 110.Li struct ifmibdata 111are as follows: 112.Bl -tag -width "ifmd_snd_drops" 113.It Li ifmd_name 114.Pq Li "char []" 115the name of the interface, including the unit number 116.It Li ifmd_pcount 117.Pq Li int 118the number of promiscuous listeners 119.It Li ifmd_flags 120.Pq Li int 121the interface's flags (defined in 122.Aq Pa net/if.h ) 123.It Li ifmd_snd_len 124.Pq Li int 125the current instantaneous length of the send queue 126.It Li ifmd_snd_drops 127.Pq Li int 128the number of packets dropped at this interface because the send queue 129was full 130.It Li ifmd_data 131.Pq Li struct if_data 132more information from a structure defined in 133.Aq Pa net/if.h 134.Pq see Xr if_data 9 135.El 136.Pp 137Class-specific information can be retrieved by examining the 138.Dv IFDATA_LINKSPECIFIC 139column instead. Note that the form and length of the structure will 140depend on the class of interface. For 141.Dv IFT_ETHER , 142.Dv IFT_ISO88023 , 143and 144.Dv IFT_STARLAN 145interfaces, the structure is called 146.Dq Li struct ifmib_iso_8802_3 147(defined in 148.Aq Pa net/if_mib.h ) , 149and implements a superset of the 150.Tn "RFC 1650" 151MIB for Ethernet-like networks. 152.\" This will eventually be defined in an ethermib(4) page. 153For 154.Dv IFT_SLIP , 155the structure is a 156.Dq Li struct sl_softc 157.Pq Aq Pa net/if_slvar.h . 158.Sh SEE ALSO 159.Xr sysctl 3 , 160.Xr intro 4 , 161.Xr ifnet 9 162.\" .Xr ethermib 4 , 163.Rs 164.%T "Definitions of Managed Objects for the Ethernet-like Interface Types Using SMIv2" 165.%A F. Kastenholz 166.%D August 1994 167.%O RFC 1650 168.Re 169.Sh BUGS 170Many Ethernet-like interfaces do not yet support the Ethernet MIB; 171the interfaces known to support it include 172.Xr ed 4 173and 174.Xr de 4 . 175Regardless, all interfaces automatically support the generic MIB. 176.Sh HISTORY 177The 178.Nm 179interface first appeared in 180.Fx 2.2 . 181