在arch下，配的dhcp老是联不同网络，只能ping自己。
现在只好用静态的，但我是有线通，这个ip什么老是变阿，真吃不消
下面是dhcpcd时候的输出。按照archlinux wiki上面的办法，我把ipv6禁用了。但还是不能配到ipv4
dhcpcd[13390]: version 5.5.6 starting
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: rebinding lease of xxx.xxx.xxx.74
dhcpcd[13390]: eth0: acknowledged xxx.xxx.xxx.74 from 10.100.112.33
dhcpcd[13390]: eth0: checking for xxx.xxx.xxx.74
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: carrier lost
dhcpcd[13424]: eth0: eth0: MTU restored to 1500
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: sendmsg: Network is unreachable
dhcpcd[13390]: eth0: carrier acquired
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: sendmsg: Cannot assign requested address
dhcpcd[13390]: eth0: rebinding lease of xxx.xxx.xxx.74
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: broadcasting for a lease
dhcpcd[13390]: eth0: offered xxx.xxx.xxx.74 from 10.100.112.33
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: acknowledged xxx.xxx.xxx.74 from 10.100.112.33
dhcpcd[13390]: eth0: checking for xxx.xxx.xxx.74
dhcpcd[13390]: eth0: sending IPv6 Router Solicitation
dhcpcd[13390]: eth0: no IPv6 Routers available
dhcpcd[13390]: eth0: leased xxx.xxx.xxx.74 for 2710 seconds
dhcpcd[13458]: eth0: eth0: MTU set to 576
dhcpcd[13390]: forked to background, child pid 13474