'\" t
-.\" Don't change the first line, it tells man that tbl is needed.
.\" This man page is Copyright (C) 1999 Andi Kleen <ak@muc.de>.
+.\"
+.\" %%%LICENSE_START(VERBATIM_ONE_PARA)
.\" Permission is granted to distribute possibly modified copies
.\" of this page provided the header is included verbatim,
.\" and in case of nontrivial modification author and date
.\" of the modification is added to the header.
+.\" %%%LICENSE_END
+.\"
.\" $Id: netdevice.7,v 1.10 2000/08/17 10:09:54 ak Exp $
.\"
.\" Modified, 2004-11-25, mtk, formatting and a few wording fixes
.\"
-.TH NETDEVICE 7 1999-05-02 "Linux Man Page" "Linux Programmer's Manual"
+.\" Modified, 2011-11-02, <bidulock@openss7.org>, added many basic
+.\" but missing ioctls, such as SIOCGIFADDR.
+.\"
+.TH NETDEVICE 7 2017-09-15 "Linux" "Linux Programmer's Manual"
.SH NAME
-netdevice \- Low level access to Linux network devices
+netdevice \- low-level access to Linux network devices
.SH SYNOPSIS
.B "#include <sys/ioctl.h>"
.br
.SH DESCRIPTION
This man page describes the sockets interface which is used to configure
network devices.
-
+.PP
Linux supports some standard ioctls to configure network devices.
They can be used on any socket's file descriptor regardless of the
family or type.
-They pass an
-.B ifreq
+Most of them pass an
+.I ifreq
structure:
-
-.nf
+.PP
+.in +4n
+.EX
struct ifreq {
char ifr_name[IFNAMSIZ]; /* Interface name */
union {
struct ifmap ifr_map;
char ifr_slave[IFNAMSIZ];
char ifr_newname[IFNAMSIZ];
- char * ifr_data;
+ char *ifr_data;
};
};
-
-struct ifconf {
- int ifc_len; /* size of buffer */
- union {
- char * ifc_buf; /* buffer address */
- struct ifreq * ifc_req; /* array of structures */
- };
-};
-.fi
-
+.EE
+.in
+.PP
Normally, the user specifies which device to affect by setting
-.B ifr_name
+.I ifr_name
to the name of the interface.
All other members of the structure may
share memory.
-.SH IOCTLS
-If an ioctl is marked as privileged then using it requires an effective
+.SS Ioctls
+If an ioctl is marked as privileged, then using it requires an effective
user ID of 0 or the
.B CAP_NET_ADMIN
capability.
-If this is not the case
+If this is not the case,
.B EPERM
will be returned.
.TP
.B SIOCGIFNAME
Given the
-.BR ifr_ifindex ,
+.IR ifr_ifindex ,
return the name of the interface in
-.BR ifr_name .
+.IR ifr_name .
This is the only ioctl which returns its result in
-.BR ifr_name .
+.IR ifr_name .
.TP
.B SIOCGIFINDEX
Retrieve the interface index of the interface into
-.BR ifr_ifindex .
+.IR ifr_ifindex .
.TP
.BR SIOCGIFFLAGS ", " SIOCSIFFLAGS
Get or set the active flag word of the device.
-.B ifr_flags
-contains a bitmask of the following values:
+.I ifr_flags
+contains a bit mask of the following values:
+.\" Do not right adjust text blocks in tables
+.na
.TS
tab(:);
c s
IFF_LOOPBACK:Interface is a loopback interface.
IFF_POINTOPOINT:Interface is a point-to-point link.
IFF_RUNNING:Resources allocated.
-IFF_NOARP:No arp protocol, L2 destination address not set.
+IFF_NOARP:T{
+No arp protocol, L2 destination address not set.
+T}
IFF_PROMISC:Interface is in promiscuous mode.
IFF_NOTRAILERS:Avoid use of trailers.
IFF_ALLMULTI:Receive all multicast packets.
IFF_DYNAMIC:T{
The addresses are lost when the interface goes down.
T}
+IFF_LOWER_UP:Driver signals L1 up (since Linux 2.6.17)
+IFF_DORMANT:Driver signals dormant (since Linux 2.6.17)
+IFF_ECHO:Echo sent packets (since Linux 2.6.25)
.TE
+.ad
+.PP
Setting the active flag word is a privileged operation, but any
process may read it.
.TP
+.BR SIOCGIFPFLAGS ", " SIOCSIFPFLAGS
+Get or set extended (private) flags for the device.
+.I ifr_flags
+contains a bit mask of the following values:
+.TS
+tab(:);
+c s
+l l.
+Private flags
+IFF_802_1Q_VLAN:Interface is 802.1Q VLAN device.
+IFF_EBRIDGE:Interface is Ethernet bridging device.
+IFF_SLAVE_INACTIVE:Interface is inactive bonding slave.
+IFF_MASTER_8023AD:Interface is 802.3ad bonding master.
+IFF_MASTER_ALB:Interface is balanced-alb bonding master.
+IFF_BONDING:Interface is a bonding master or slave.
+IFF_SLAVE_NEEDARP:Interface needs ARPs for validation.
+IFF_ISATAP:Interface is RFC4214 ISATAP interface.
+.TE
+.PP
+Setting the extended (private) interface flags is a privileged operation.
+.TP
+.BR SIOCGIFADDR ", " SIOCSIFADDR
+Get or set the address of the device using
+.IR ifr_addr .
+Setting the interface address is a privileged operation.
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+.TP
+.BR SIOCGIFDSTADDR ", " SIOCSIFDSTADDR
+Get or set the destination address of a point-to-point device using
+.IR ifr_dstaddr .
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+Setting the destination address is a privileged operation.
+.TP
+.BR SIOCGIFBRDADDR ", " SIOCSIFBRDADDR
+Get or set the broadcast address for a device using
+.IR ifr_brdaddr .
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+Setting the broadcast address is a privileged operation.
+.TP
+.BR SIOCGIFNETMASK ", " SIOCSIFNETMASK
+Get or set the network mask for a device using
+.IR ifr_netmask .
+For compatibility, only
+.B AF_INET
+addresses are accepted or returned.
+Setting the network mask is a privileged operation.
+.TP
.BR SIOCGIFMETRIC ", " SIOCSIFMETRIC
Get or set the metric of the device using
-.BR ifr_metric .
+.IR ifr_metric .
This is currently not implemented; it sets
-.B ifr_metric
+.I ifr_metric
to 0 if you attempt to read it and returns
.B EOPNOTSUPP
if you attempt to set it.
.TP
.BR SIOCGIFMTU ", " SIOCSIFMTU
Get or set the MTU (Maximum Transfer Unit) of a device using
-.BR ifr_mtu .
+.IR ifr_mtu .
Setting the MTU is a privileged operation.
Setting the MTU to
too small values may cause kernel crashes.
.TP
.BR SIOCGIFHWADDR ", " SIOCSIFHWADDR
Get or set the hardware address of a device using
-.BR ifr_hwaddr .
+.IR ifr_hwaddr .
The hardware address is specified in a struct
.IR sockaddr .
.I sa_family
.TP
.B SIOCSIFHWBROADCAST
Set the hardware broadcast address of a device from
-.BR ifr_hwaddr .
+.IR ifr_hwaddr .
This is a privileged operation.
.TP
.BR SIOCGIFMAP ", " SIOCSIFMAP
Get or set the interface's hardware parameters using
-.BR ifr_map .
+.IR ifr_map .
Setting the parameters is a privileged operation.
-
-.nf
+.IP
+.in +4n
+.EX
struct ifmap {
unsigned long mem_start;
unsigned long mem_end;
unsigned char dma;
unsigned char port;
};
-.fi
-
+.EE
+.in
+.IP
The interpretation of the ifmap structure depends on the device driver
and the architecture.
.TP
.BR SIOCADDMULTI ", " SIOCDELMULTI
Add an address to or delete an address from the device's link layer
multicast filters using
-.BR ifr_hwaddr .
+.IR ifr_hwaddr .
These are privileged operations.
See also
.BR packet (7)
.TP
.BR SIOCGIFTXQLEN ", " SIOCSIFTXQLEN
Get or set the transmit queue length of a device using
-.BR ifr_qlen .
+.IR ifr_qlen .
Setting the transmit queue length is a privileged operation.
.TP
.B SIOCSIFNAME
Changes the name of the interface specified in
-.BR ifr_name
+.I ifr_name
to
-.BR ifr_newname .
+.IR ifr_newname .
This is a privileged operation.
-It is only allowed when the interface
+It is allowed only when the interface
is not up.
.TP
.B SIOCGIFCONF
Return a list of interface (transport layer) addresses.
This currently
-means only addresses of the AF_INET (IPv4) family for compatibility.
-The user passes a
-.B ifconf
-structure as argument to the ioctl.
-It contains a pointer to an array of
+means only addresses of the
+.B AF_INET
+(IPv4) family for compatibility.
+Unlike the others, this ioctl passes an
+.I ifconf
+structure:
+.IP
+.in +4n
+.EX
+struct ifconf {
+ int ifc_len; /* size of buffer */
+ union {
+ char *ifc_buf; /* buffer address */
+ struct ifreq *ifc_req; /* array of structures */
+ };
+};
+.EE
+.in
+.IP
+If
+.I ifc_req
+is NULL,
+.B SIOCGIFCONF
+returns the necessary buffer size in bytes
+for receiving all available addresses in
+.IR ifc_len .
+Otherwise,
+.I ifc_req
+contains a pointer to an array of
+.I ifreq
+structures to be filled with all currently active L3 interface addresses.
+.I ifc_len
+contains the size of the array in bytes.
+Within each
.I ifreq
-structures in
-.B ifc_req
-and its length in bytes in
-.BR ifc_len .
-The kernel fills the ifreqs with all current L3 interface addresses that
-are running:
+structure,
.I ifr_name
-contains the interface name (eth0:1 etc.),
+will receive the interface name, and
.I ifr_addr
the address.
-The kernel returns with the actual length in
+The actual number of bytes transferred is returned in
.IR ifc_len .
-If
+.IP
+If the size specified by
+.I ifc_len
+is insufficient to store all the addresses,
+the kernel will skip the exceeding ones and return success.
+There is no reliable way of detecting this condition once it has occurred.
+It is therefore recommended to either determine the necessary buffer size
+beforehand by calling
+.B SIOCGIFCONF
+with
+.I ifc_req
+set to NULL, or to retry the call with a bigger buffer whenever
.I ifc_len
-is equal to the original length the buffer probably has overflowed
-and you should retry with a bigger buffer to get all addresses.
-When no error occurs the ioctl returns 0;
-otherwise \-1.
-Overflow is not an error.
-.\" FIXME Slaving isn't supported in 2.2
+upon return differs by less than
+.I sizeof(struct ifreq)
+from its original value.
+.IP
+If an error occurs accessing the
+.I ifconf
+or
+.I ifreq
+structures,
+.B EFAULT
+will be returned.
+.\" Slaving isn't supported in 2.2
.\" .
.\" .TP
.\" .BR SIOCGIFSLAVE ", " SIOCSIFSLAVE
.\" Get or set the slave device using
-.\" .BR ifr_slave .
+.\" .IR ifr_slave .
.\" Setting the slave device is a privileged operation.
.\" .PP
-.\" FIXME add amateur radio stuff.
+.\" FIXME . add amateur radio stuff.
.PP
-Most protocols support their own ioctls to configure protocol specific
+Most protocols support their own ioctls to configure protocol-specific
interface options.
See the protocol man pages for a description.
-For configuring IP addresses see
+For configuring IP addresses, see
.BR ip (7).
.PP
-In addition some devices support private ioctls.
+In addition, some devices support private ioctls.
These are not described here.
.SH NOTES
Strictly speaking,
.B SIOCGIFCONF
-is IP specific and belongs in
+and the other ioctls that accept or return only
+.B AF_INET
+socket addresses,
+are IP-specific and belong in
.BR ip (7).
-.LP
+.PP
The names of interfaces with no addresses or that don't have the
.B IFF_RUNNING
flag set can be found via
.IR /proc/net/dev .
-.LP
-Local IPv6 IP addresses can be found via /proc/net or via
+.PP
+Local IPv6 IP addresses can be found via
+.I /proc/net
+or via
.BR rtnetlink (7).
.SH BUGS
glibc 2.1 is missing the
.I ifr_newname
-macro in net/if.h.
+macro in
+.IR <net/if.h> .
Add the following to your program as a workaround:
-.sp
-.RS
-.nf
+.PP
+.in +4n
+.EX
#ifndef ifr_newname
#define ifr_newname ifr_ifru.ifru_slave
#endif
-.fi
-.RE
-.SH "SEE ALSO"
+.EE
+.in
+.SH SEE ALSO
+.BR proc (5),
.BR capabilities (7),
.BR ip (7),
-.BR proc (7),
.BR rtnetlink (7)
projects / thirdparty / man-pages.git / blobdiff