由于fedora21版本的使用的有线设备名字改为enp4s0，所以不能够按照一般的eth0的linux系统去修改MAC地址，可以按照如下步骤修改MAC地址：
1,输入：ifconfig 命令首先查看mac地址是多少，看看有线设备是不是enpts0:
enp4s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
inet 58.198.102.27 netmask 255.255.255.0 broadcast 58.198.102.255
inet6 2001:da8:8006:407:ca1f:66ff:fe49:941b prefixlen 64 scopeid 0x0<global>
inet6 fe80::ca1f:66ff:fe49:941b prefixlen 64 scopeid 0x20<link>
ether c8:1f:66:49:94:1b txqueuelen 1000 (Ethernet)
RX packets 50120 bytes 3152813 (3.0 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 2117 bytes 181616 (177.3 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 176 bytes 15828 (15.4 KiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 176 bytes 15828 (15.4 KiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
2，输入：sudo ifconfig enp4s0 down
3:输入：cd /etc/sysconfig/network-scripts/ 找到ifcfg-enp4s0文件
ifcfg-enp4s0文件为：
MACADDR=C8:1F:66:49:94:1B
TYPE="Ethernet"
BOOTPROTO="dhcp"
DEFROUTE="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp4s0"
UUID="5981df8c-4764-4338-bf48-32d23c017de1"
ONBOOT="yes"
PEERDNS=yes
PEERROUTES=yes
IPV6_PEERDNS=yes
IPV6_PEERROUTES=yes
~
~
修改其中的"HWADDR=xx:xx:xx:xx:xx:xx"为"MACADDR=xx:xx:xx:xx:xx:xx"，即可
4，输入：sudo ifconfig enp4s0 up 启动enp4s0
5，输入：service network start ，如果出现network.service failed情况，请往下如下操作：
6：输入：systemctl status network.service
network.service - LSB: Bring up/down networking
Loaded: loaded (/etc/rc.d/init.d/network)
Active: failed (Result: exit-code) since Thu 2015-07-16 09:10:18 EDT; 58s ago
Docs: man:systemd-sysv-generator(8)Process: 6974 ExecStart=/etc/rc.d/init.d/network start (code=exited, status=1/FAILURE)
7,输入：systemctl enable NetworkManager-wait-online.service
8，systemctl start network.service
9:输入：systemctl status network.service
network.service - LSB: Bring up/down networking
Loaded: loaded (/etc/rc.d/init.d/network)
Active: activating (<span style="color:#FF6666;">start</span>) since Thu 2015-07-16 09:13:54 EDT; 27s ago
Docs: man:systemd-sysv-generator(8)
Control: 8564 (network)
CGroup: /system.slice/network.service
├─8564 /bin/bash /etc/rc.d/init.d/network start
├─8925 /bin/bash ./ifup Wired_connection_3 boot
└─8956 nmcli con up uuid 4f530eb2-a6aa-4e6f-828f-1d5cc32371ba
现在重启，永久修改MAC地址。
Snow Leopard、Ubuntu、Windows下修改网卡MAC地址：http://www.linuxdiyf.com/linux/9107.html
Linux下获取eth网卡MAC地址的代码 ：http://www.linuxdiyf.com/linux/9004.html
Linux下修改错误的MAC地址[图文]：http://www.linuxdiyf.com/linux/8421.html
Linux下修改MAC地址的工具macchanger的使用：http://www.linuxdiyf.com/linux/9724.html
Ubuntu更改mac地址：http://www.linuxdiyf.com/linux/1011.html