我意识到之前问过很多“无法获取”的问题，但似乎都无法解决我的问题。
这是我输入后得到的export http_proxy=http://198.23.143.4:8080
结果sudo apt-get update
我新安装了 Ubuntu 11.10（不是升级版）
Err http://extras.ubuntu.com oneiric InRelease
Err http://us.archive.ubuntu.com oneiric InRelease
Err http://us.archive.ubuntu.com oneiric-updates InRelease
Err http://us.archive.ubuntu.com oneiric-backports InRelease
Err http://security.ubuntu.com oneiric-security InRelease
Err http://extras.ubuntu.com oneiric Release.gpg
Unable to connect to 198.23.143.4:8080:
Err http://security.ubuntu.com oneiric-security Release.gpg
Unable to connect to 198.23.143.4:8080:
Err http://us.archive.ubuntu.com oneiric Release.gpg
Unable to connect to 198.23.143.4:8080:
Err http://us.archive.ubuntu.com oneiric-updates Release.gpg
Unable to connect to 198.23.143.4:8080:
Err http://us.archive.ubuntu.com oneiric-backports Release.gpg
Unable to connect to 198.23.143.4:8080:
Reading package lists... Done
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric/InRelease
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-updates/InRelease
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-backports/InRelease
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/oneiric-security/InRelease
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/oneiric/InRelease
W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/oneiric/Release.gpg Unable to connect to 198.23.143.4:8080:
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric/Release.gpg Unable to connect to 198.23.143.4:8080:
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-updates/Release.gpg Unable to connect to 198.23.143.4:8080:
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/oneiric-backports/Release.gpg Unable to connect to 198.23.143.4:8080:
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/oneiric-security/Release.gpg Unable to connect to 198.23.143.4:8080:
W: Some index files failed to download. They have been ignored, or old ones used instead.
答案1
根据您提供的错误，似乎您的服务器无法与代理服务器建立 TCP 连接。
您能否 telnet（建立 TCP 连接）至 198.23.143.4 的 8080 端口？
telnet 198.23.143.4 8080