1 #!/bin/sh 2 # Virtual ethernet interface control script 3 # Sometimes, we need a virtual interface of arbitrary name and configuration 4 # that we can do dhcp on. This script is for those times. 5 6 # Basically, 7 # $ veth setup foo 127.0.1 8 # $ dhclient foo 9 # ... 10 # $ veth teardown foo 11 # Would set up an ethernet interface called 'foo' whose dhcpd is at 127.0.1.1 12 # and which will allocate addresses from 127.0.1.0/24. Note that using anything 13 # inside 127.0.0.0/8 is a bad idea here, since lo already handles those. 14 15 usage () { 16 echo "Usage: $0 <command> [args...]" 17 echo " setup <iface> <base> Sets up <iface> for <base>.0/24" 18 echo " teardown <iface> Tears down <iface>" 19 } 20 21 setup () { 22 iface="$1" 23 base="$2" 24 peer_iface="${iface}p" 25 lease_file="/tmp/dnsmasq.${iface}.leases" 26 pid_file="/tmp/dnsmasq.${iface}.pid" 27 ip link add name "$iface" type veth peer name "$peer_iface" 28 ifconfig "$peer_iface" "${base}.0/32" 29 ifconfig "$peer_iface" up 30 ifconfig "$iface" up 31 route add -host 255.255.255.255 dev "$peer_iface" 32 truncate -s 0 "$lease_file" 33 dnsmasq --pid-file="$pid_file" \ 34 --dhcp-leasefile="$lease_file" \ 35 --dhcp-range="${base}.2,${base}.254" \ 36 --port=0 \ 37 --interface="$peer_iface" \ 38 --bind-interfaces 39 } 40 41 teardown () { 42 iface="$1" 43 pid_file="/tmp/dnsmasq.${iface}.pid" 44 [ -f "$pid_file" ] && kill -TERM $(cat "$pid_file") 45 route del -host 255.255.255.255 46 ip link del "$iface" 47 } 48 49 if [ -z "$1" ]; then 50 usage 51 exit 1 52 fi 53 54 command="$1" ; shift 55 case "$command" in 56 setup) 57 setup "$@" 58 ;; 59 teardown) 60 teardown "$@" 61 ;; 62 *) 63 usage 64 ;; 65 esac 66
