我读过很多讨论类似问题的帖子，但任何方法都对我有用。当我尝试进入 github.com 时，它显示：
无法连接
Firefox 无法与 github.com 上的服务器建立连接。
我尝试过使用其他浏览器，但结果相同。（现在我使用的是 Firefox Quantum）。我已经使用 github 进行了托管：
$ host www.github.com
www.github.com is an alias for github.com.
github.com has address 192.30.253.113
github.com has address 192.30.253.112
github.com mail is handled by 5 alt2.aspmx.l.google.com.
github.com mail is handled by 1 aspmx.l.google.com.
github.com mail is handled by 10 alt3.aspmx.l.google.com.
github.com mail is handled by 10 alt4.aspmx.l.google.com.
github.com mail is handled by 5 alt1.aspmx.l.google.com.
和：
ping -c 3 www.github.com
PING github.com (192.30.253.113) 56(84) bytes of data.
From 192.168.254.100 icmp_seq=1 Destination Host Unreachable
和： traceroute www.github.com
traceroute to www.github.com (192.30.253.113), 30 hops max, 60 byte packets
1 192.168.254.100 (192.168.254.100) 3061.719 ms !H 3061.680 ms !H 3061.672 ms !H
但使用谷歌一切都很好：
$ traceroute www.google.es
traceroute to www.google.es (216.58.210.163), 30 hops max, 60 byte packets
1 192.168.0.1 (192.168.0.1) 0.649 ms 1.042 ms 1.770 ms
2 static-10-0-235-87.ipcom.comunitel.net (87.235.0.10) 20.051 ms 22.691 ms 24.117 ms
3 172.29.144.110 (172.29.144.110) 25.077 ms 172.29.144.106 (172.29.144.106) 27.848 ms 172.29.144.110 (172.29.144.110) 28.457 ms
谢谢
ip 路由显示：
default via 192.168.0.1 dev enp3s0f1 proto static metric 100
default via 192.168.0.1 dev wlp2s0 proto static metric 600
169.254.0.0/16 dev enp3s0f1 proto static scope link metric 1000
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown
192.0.0.0/8 dev vboxnet0 proto kernel scope link src 192.168.254.100 linkdown
192.168.0.0/24 dev enp3s0f1 proto kernel scope link src 192.168.0.161 metric 100
192.168.0.0/24 dev wlp2s0 proto kernel scope link src 192.168.0.156 metric 600