apt-get update 和 upgrade 都挂起：
sudo apt-get update
[sudo] password for xxx:
0% [Connecting to archive.ubuntu.com (2001:67c:1360:8001::17)]
我可以 ping archive.ubuntu.com：
ping archive.ubuntu.com
PING archive.ubuntu.com (91.189.88.162) 56(84) bytes of data.
64 bytes from yukinko.canonical.com (91.189.88.162): icmp_seq=1 ttl=50 time=42.2 ms
64 bytes from yukinko.canonical.com (91.189.88.162): icmp_seq=2 ttl=50 time=42.1 ms
64 bytes from yukinko.canonical.com (91.189.88.162): icmp_seq=3 ttl=50 time=42.1 ms
^C
--- archive.ubuntu.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2002ms
rtt min/avg/max/mdev = 42.169/42.206/42.265/0.240 ms
我检查了这个问题，我认为这不是同一个问题。 …