FREEBSD使用ng_eiface和ng_bridge创建虚拟以太网接口

使用通用以太网接口 netgraph 节点，可以创建可通过 ifconfig(8) 访问的新接口，使用以太网桥接 netgraph 节点类型可以在不同的以太网节点类型之间进行桥接。通过组合这两种类型，可以在同一物理接口上创建具有不同以太网 (MAC) 地址的多个接口。这是从标准 FreeBSD 发行版附带的 netgraph ether.bridge 示例脚本修改而来的示例脚本：

1 #!/bin/sh
2 #
3 # Author: Jan Melen-jan(at)melen.org
4 #
5 # This script sets up an Ethernet bridging network across multiple
6 # ng_eiface(4) using the ng_bridge(4) and ng_ether(4) netgraph
7 # node types.
8 #
9
10 BRIDGE_NAME="bnet0"
11
12 VIRTUAL_IFACES="ngeth0 ngeth1 ngeth2"
13 LOCAL_IFACE="bge0"
14
15 # Routine to verify node's existence.
16 vether_verify() {
17 ngctl info ${BRIDGE_NAME}: >/dev/null 2>&1
18 if [ $? -ne 0 ]; then
19 echo "${BRIDGE_NAME}: bridge network not found"
20 exit 1
21 fi
22 }
23
24 # Start/restart routine.
25 vether_start() {
26
27 # Load netgraph KLD's as necessary.
28 for KLD in ng_ether ng_bridge; do
29 if ! kldstat -v | grep -qw ${KLD}; then
30 echo -n "Loading ${KLD}.ko... "
31 kldload ${KLD} || exit 1
32 echo "done"
33 fi
34 done
35
36 # Reset all interfaces.
37 vether_stop
38
39 # Verify all interfaces exist.
40 LINKNUM=2
41 ETHERADDR=`ifconfig ${LOCAL_IFACE} ether | grep "ether" | cut -b 8-22`
42 for ETHER in ${VIRTUAL_IFACES}; do
43 if ! ngctl info ${ETHER}: >/dev/null 2>&1; then
44 ngctl mkpeer . eiface hook ether
45 fi
46 ifconfig ${ETHER} ether ${ETHERADDR}${LINKNUM}
47 ifconfig ${ETHER} up || exit 1
48 LINKNUM=`expr ${LINKNUM} + 1`
49 done
50
51 # Create new ng_bridge(4) node, attached to the first interface.
52 ngctl mkpeer ${LOCAL_IFACE}: bridge lower link0 || exit 1
53 ngctl name ${LOCAL_IFACE}:lower ${BRIDGE_NAME} || exit 1
54 ngctl connect ${LOCAL_IFACE}: ${BRIDGE_NAME}: upper link1 || exit 1
55
56 LINKNUM=2
57 # Attach other interfaces as well.
58 for ETHER in ${VIRTUAL_IFACES}; do
59 if [ ${LINKNUM} != 0 ]; then
60 ngctl connect ${ETHER}: ${BRIDGE_NAME}: \
61 ether link${LINKNUM} || exit 1
62 fi
63 LINKNUM=`expr ${LINKNUM} + 1`
64 done
65
66 # Set all interfaces in promiscuous mode and don't overwrite src addr.
67 for ETHER in ${LOCAL_IFACE}; do
68 ngctl msg ${ETHER}: setpromisc 1
69 ngctl msg ${ETHER}: setautosrc 0
70 done
71 }
72
73 # Stop routine.
74 vether_stop() {
75 ngctl kill ${BRIDGE_NAME}: >/dev/null 2>&1
76 for ETHER in ${VIRTUAL_IFACES} ${LOCAL_IFACE}; do
77 ngctl kill ${ETHER}: >/dev/null 2>&1
78 done
79 }
80
81 # Main entry point.
82 case $1 in
83 start)
84 vether_start
85 ;;
86 stop)
87 vether_verify
88 vether_stop
89 ;;
90 *)
91 echo "usage: $0 [ start | stop ]"
92 exit 1
93 esac