【背景】
折腾：
【记录】尝试用QEMU模拟ARM开发板去加载并运行Uboot，kernel，rootfs
期间，需要为QEMU准备qemu-ifup和qemu-ifdown。
【折腾过程】
1.确认是已有tun设备节点的：
crifan@ubuntu:embedded$ ls /dev/net/ tun crifan@ubuntu:embedded$ ls /dev/net/ -hla total 0 drwxr-xr-x 2 root root 60 Aug 16 02:13 . drwxr-xr-x 15 root root 4.3K Aug 16 02:13 .. crw-rw-rwT 1 root root 10, 200 Aug 16 02:13 tun crifan@ubuntu:embedded$ file /dev/net/tun /dev/net/tun: sticky character special
2.参考：
http://en.wikibooks.org/wiki/QEMU/Networking
去创建对应的qemu-ifup和qemu-ifdown：
（1）qemu-ifup：
内容为：
#!/bin/sh # # script to bring up the tun device in QEMU in bridged mode # first parameter is name of tap device (e.g. tap0) # # some constants specific to the local host - change to suit your host # ETH0IPADDR=192.168.0.3 GATEWAY=192.168.0.1 BROADCAST=192.168.0.255 # # First take eth0 down, then bring it up with IP address 0.0.0.0 # /sbin/ifdown eth0 /sbin/ifconfig eth0 0.0.0.0 promisc up # # Bring up the tap device (name specified as first argument, by QEMU) # /usr/sbin/openvpn --mktun --dev $1 --user `id -un` /sbin/ifconfig $1 0.0.0.0 promisc up # # create the bridge between eth0 and the tap device # /usr/sbin/brctl addbr br0 /usr/sbin/brctl addif br0 eth0 /usr/sbin/brctl addif br0 $1 # # only a single bridge so loops are not possible, turn off spanning tree protocol # /usr/sbin/brctl stp br0 off # # Bring up the bridge with ETH0IPADDR and add the default route # /sbin/ifconfig br0 $ETH0IPADDR netmask 255.255.255.0 broadcast $BROADCAST /sbin/route add default gw $GATEWAY # # stop firewall - comment this out if you don't use Firestarter # /sbin/service firestarter stop
（2）qemu-ifdown
#!/bin/sh # # Script to bring down and delete bridge br0 when QEMU exits # # Bring down eth0 and br0 # /sbin/ifdown eth0 /sbin/ifdown br0 /sbin/ifconfig br0 down # # Delete the bridge # /usr/sbin/brctl delbr br0 # # bring up eth0 in "normal" mode # /sbin/ifconfig eth0 -promisc /sbin/ifup eth0 # # delete the tap device # /usr/sbin/openvpn --rmtun --dev $1 # # start firewall again # /sbin/service firestarter start
然后再拷贝到etc，并且加上可执行的权限：
crifan@ubuntu:ifup_ifdown$ gedit qemu-ifup (gedit:3688): Gtk-WARNING **: Attempting to read the recently used resources file at `/home/crifan/.local/share/recently-used.xbel', but the parser failed: Failed to open file '/home/crifan/.local/share/recently-used.xbel': Permission denied. crifan@ubuntu:ifup_ifdown$ gedit qemu-ifdown crifan@ubuntu:ifup_ifdown$ ls qemu-ifdown qemu-ifup crifan@ubuntu:ifup_ifdown$ cp qemu-ifup qemu-ifdown /etc/ cp: cannot create regular file ‘/etc/qemu-ifup’: Permission denied cp: cannot create regular file ‘/etc/qemu-ifdown’: Permission denied crifan@ubuntu:ifup_ifdown$ sudo cp qemu-ifup qemu-ifdown /etc/ crifan@ubuntu:ifup_ifdown$ cd /etc crifan@ubuntu:etc$ ls acpi host.conf profile.d adduser.conf hostname protocols adjtime hosts pulse alternatives hosts.allow python anacrontab hosts.deny python2.7 apg.conf hp python3 apm ifplugd python3.3 apparmor init qemu-ifdown apparmor.d init.d qemu-ifup apport initramfs-tools rc0.d apt inputrc rc1.d aptdaemon insserv rc2.d at-spi2 insserv.conf rc3.d avahi insserv.conf.d rc4.d bash.bashrc iproute2 rc5.d bash_completion issue rc6.d bash_completion.d issue.net rc.local bindresvport.blacklist java rc.local~ blkid.conf java-7-openjdk rcS.d blkid.tab kbd remote-login-service.conf bluetooth kernel resolvconf bonobo-activation kernel-img.conf resolv.conf brlapi.key kerneloops.conf rmt brltty ldap rpc brltty.conf ld.so.cache rsyslog.conf ca-certificates ld.so.conf rsyslog.d ca-certificates.conf ld.so.conf.d samba calendar legal sane.d chatscripts libaudit.conf securetty checkbox.d libnl-3 security colord.conf libpaper.d selinux compizconfig libreoffice sensors3.conf ConsoleKit lightdm sensors.d console-setup lintianrc services cracklib locale.alias sgml cron.d localtime shadow cron.daily logcheck shadow~ cron.hourly login.defs shadow- cron.monthly logrotate.conf shells crontab logrotate.d signond.conf cron.weekly lsb-base signon-ui cups lsb-base-logging.sh skel cupshelpers lsb-release snmp dbus-1 ltrace.conf sound debconf.conf magic speech-dispatcher debian_version magic.mime ssh default mailcap ssl deluser.conf mailcap.order subversion depmod.d manpath.config sudoers dhcp mime.types sudoers~ dhcp3 mke2fs.conf sudoers.d dictionaries-common modprobe.d sysctl.conf dkms modules sysctl.d dnsmasq.d motd systemd doc-base mtab terminfo dpkg mtab.fuselock texmf drirc mtools.conf thunderbird emacs nanorc timezone environment netscsid.conf tpvmlp.conf firefox network ucf.conf fonts NetworkManager udev foomatic networks udisks2 fstab newt ufw fstab.d nsswitch.conf updatedb.conf fuse.conf obex-data-server update-manager gai.conf opt update-motd.d gconf os-release update-notifier gdb pam.conf UPower ghostscript pam.d upstart-xsessions gnome papersize usb_modeswitch.conf gnome-app-install passwd usb_modeswitch.d gnome-settings-daemon passwd~ vim gnome-vfs-2.0 passwd- vmware-tools groff pcmcia vtrgb group perl wgetrc group- pkcs11 wodim.conf grub.d pm wpa_supplicant gshadow pnm2ppa.conf X11 gshadow- polkit-1 xdg gtk-2.0 popularity-contest.conf xml gtk-3.0 ppp xul-ext hdparm.conf profile zsh_command_not_found crifan@ubuntu:etc$ sudo chmod +x qemu-ifup crifan@ubuntu:etc$ sudo chmod +x qemu-ifdown crifan@ubuntu:etc$ ls qemu-if& -lha [1] 3733 ls: cannot access qemu-if: No such file or directory No command '-lha' found, did you mean: Command 'lha' from package 'jlha-utils' (universe) Command 'lha' from package 'lhasa' (universe) Command 'lha' from package 'lha' (multiverse) Command 'jlha' from package 'jlha-utils' (universe) -lha: command not found [1]+ Exit 2 ls --color=auto qemu-if crifan@ubuntu:etc$ ls qemu-if* -lha -rwxr-xr-x 1 root root 428 Aug 16 02:51 qemu-ifdown -rwxr-xr-x 1 root root 1.1K Aug 16 02:51 qemu-ifup crifan@ubuntu:etc$
如此，就完成了。
【总结】
主要就是：
创建对应的qemu-ifup和qemu-ifdown两个文件，然后拷贝到etc中，并且给予execute的权限。