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Overview
Control flow when running one of:
ip link showip link show eth0ip link set eth0 upip link set eth0 down
Links:
Structures
struct iplink_req
From ip/ip_common.h:
struct iplink_req {
struct nlmsghdr n;
struct ifinfomsg i;
char buf[1024];
};
struct ifinfomsg
From include/uapi/linux/rtnetlink.h:
/* struct ifinfomsg
* passes link level specific information, not dependent
* on network protocol.
*/
struct ifinfomsg {
unsigned char ifi_family;
unsigned char __ifi_pad;
unsigned short ifi_type; /* ARPHRD_* */
int ifi_index; /* Link index */
unsigned ifi_flags; /* IFF_* flags */
unsigned ifi_change; /* IFF_* change mask */
};
ifi_flags
From include/uapi/linux/if.h:
enum net_device_flags {
/* for compatibility with glibc net/if.h */
#if __UAPI_DEF_IF_NET_DEVICE_FLAGS
IFF_UP = 1<<0, /* sysfs */
IFF_BROADCAST = 1<<1, /* volatile */
IFF_DEBUG = 1<<2, /* sysfs */
IFF_LOOPBACK = 1<<3, /* volatile */
IFF_POINTOPOINT = 1<<4, /* volatile */
IFF_NOTRAILERS = 1<<5, /* sysfs */
IFF_RUNNING = 1<<6, /* volatile */
IFF_NOARP = 1<<7, /* sysfs */
IFF_PROMISC = 1<<8, /* sysfs */
IFF_ALLMULTI = 1<<9, /* sysfs */
IFF_MASTER = 1<<10, /* volatile */
IFF_SLAVE = 1<<11, /* volatile */
IFF_MULTICAST = 1<<12, /* sysfs */
IFF_PORTSEL = 1<<13, /* sysfs */
IFF_AUTOMEDIA = 1<<14, /* sysfs */
IFF_DYNAMIC = 1<<15, /* sysfs */
#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS */
#if __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO
IFF_LOWER_UP = 1<<16, /* volatile */
IFF_DORMANT = 1<<17, /* volatile */
IFF_ECHO = 1<<18, /* volatile */
#endif /* __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO */
};
Usage
NAME
ip-link - network device configuration
SYNOPSIS
ip link { COMMAND | help }
ip link add [ link DEVICE ] [ name ] NAME
[ txqueuelen PACKETS ]
[ address LLADDR ] [ broadcast LLADDR ]
[ mtu MTU ] [ index IDX ]
[ numtxqueues QUEUE_COUNT ] [ numrxqueues QUEUE_COUNT ]
[ gso_max_size BYTES ] [ gso_max_segs SEGMENTS ]
type TYPE [ ARGS ]
ip link delete { DEVICE | group GROUP } type TYPE [ ARGS ]
ip link set { DEVICE | group GROUP }
[ { up | down } ]
[ type ETYPE TYPE_ARGS ]
[ arp { on | off } ]
[ dynamic { on | off } ]
[ multicast { on | off } ]
[ allmulticast { on | off } ]
[ promisc { on | off } ]
[ protodown { on | off } ]
[ trailers { on | off } ]
[ txqueuelen PACKETS ]
[ name NEWNAME ]
[ address LLADDR ]
[ broadcast LLADDR ]
[ mtu MTU ]
[ netns { PID | NETNSNAME } ]
[ link-netnsid ID ]
[ alias NAME ]
[ vf NUM [ mac LLADDR ]
[ VFVLAN-LIST ]
[ rate TXRATE ]
[ max_tx_rate TXRATE ]
[ min_tx_rate TXRATE ]
[ spoofchk { on | off } ]
[ query_rss { on | off } ]
[ state { auto | enable | disable } ]
[ trust { on | off } ]
[ node_guid eui64 ]
[ port_guid eui64 ] ]
[ { xdp | xdpgeneric | xdpdrv | xdpoffload } { off |
object FILE [ section NAME ] [ verbose ] |
pinned FILE } ]
[ master DEVICE ]
[ nomaster ]
[ vrf NAME ]
[ addrgenmode { eui64 | none | stable_secret | random } ]
[ macaddr { flush | { add | del } MACADDR | set [ MACADDR [ MACADDR [ ... ] ]
] } ]
ip link show [ DEVICE | group GROUP ] [ up ] [ master DEVICE ] [ type ETYPE ] [ vrf
NAME ]
ip link xstats type TYPE [ ARGS ]
ip link afstats [ dev DEVICE ]
ip link help [ TYPE ]
TYPE := [ bridge | bond | can | dummy | hsr | ifb | ipoib | macvlan | macvtap | vcan
| vxcan | veth | vlan | vxlan | ip6tnl | ipip | sit | gre | gretap | erspan |
ip6gre | ip6gretap | ip6erspan | vti | nlmon | ipvlan | lowpan | geneve | vrf
| macsec | netdevsim | rmnet ]
ETYPE := [ TYPE | bridge_slave | bond_slave ]
VFVLAN-LIST := [ VFVLAN-LIST ] VFVLAN
VFVLAN := [ vlan VLANID [ qos VLAN-QOS ] [ proto VLAN-PROTO ] ]
ip/iplink.c
do_iplink()
int do_iplink(int argc, char **argv)
{
if (argc < 1)
return ipaddr_list_link(0, NULL);
if (iplink_have_newlink()) {
if (matches(*argv, "add") == 0)
return iplink_modify(RTM_NEWLINK,
NLM_F_CREATE|NLM_F_EXCL,
argc-1, argv+1);
if (matches(*argv, "set") == 0 ||
matches(*argv, "change") == 0)
return iplink_modify(RTM_NEWLINK, 0,
argc-1, argv+1);
if (matches(*argv, "replace") == 0)
return iplink_modify(RTM_NEWLINK,
NLM_F_CREATE|NLM_F_REPLACE,
argc-1, argv+1);
if (matches(*argv, "delete") == 0)
return iplink_modify(RTM_DELLINK, 0,
argc-1, argv+1);
} else {
#if IPLINK_IOCTL_COMPAT
if (matches(*argv, "set") == 0)
return do_set(argc-1, argv+1);
#endif
... snip ...
do_set()
static int do_set(int argc, char **argv)
{
char *dev = NULL;
__u32 mask = 0;
__u32 flags = 0;
int qlen = -1;
int mtu = -1;
char *newaddr = NULL;
char *newbrd = NULL;
struct ifreq ifr0, ifr1;
char *newname = NULL;
int htype, halen;
while (argc > 0) {
if (strcmp(*argv, "up") == 0) {
mask |= IFF_UP;
flags |= IFF_UP;
} else if (strcmp(*argv, "down") == 0) {
mask |= IFF_UP;
flags &= ~IFF_UP;
... snip ...
if (mask)
return do_chflags(dev, flags, mask);
return 0;
}