Ошибка обновления Ubuntu 12.04

Я пытаюсь обновить свой ubuntu с помощью «sudo-apt-get update» Ниже приведена ошибка, которую я получаю. Пожалуйста, помогите мне решить.

$ sudo apt-get update
Err http://security.ubuntu.com precise-security Release.gpg                                                                                           
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://ppa.launchpad.net precise Release.gpg                                                                                                      
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://ubuntu.mirror.ac.ke precise Release.gpg                                                                                                    
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://ubuntu.mirror.ac.ke precise-security Release.gpg                                                                                           
  Unable to connect to 172.16.63.15:3128:
Err http://ubuntu.mirror.ac.ke precise-updates Release.gpg                                                                                            
  Unable to connect to 172.16.63.15:3128:
Err http://extras.ubuntu.com precise Release.gpg                                                                                                      
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://archive.canonical.com precise Release.gpg                                                                                                  
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://apt.insynchq.com raring Release.gpg                                                                                                        
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://dl.google.com stable Release.gpg                                                                                                           
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Err http://toolbelt.heroku.com ./ Release.gpg                                                                                                         
  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out
Reading package lists... Done                                                                                                                         
W: Failed to fetch http://ubuntu.mirror.ac.ke/ubuntu/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://extras.ubuntu.com/ubuntu/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://archive.canonical.com/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://apt.insynchq.com/ubuntu/dists/raring/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/precise-security/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://ubuntu.mirror.ac.ke/ubuntu/dists/precise-security/Release.gpg  Unable to connect to 172.16.63.15:3128:

W: Failed to fetch http://ubuntu.mirror.ac.ke/ubuntu/dists/precise-updates/Release.gpg  Unable to connect to 172.16.63.15:3128:

W: Failed to fetch http://dl.google.com/linux/chrome/deb/dists/stable/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://toolbelt.heroku.com/ubuntu/./Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Failed to fetch http://ppa.launchpad.net/webupd8team/y-ppa-manager/ubuntu/dists/precise/Release.gpg  Could not connect to 172.16.63.15:3128 (172.16.63.15), connection timed out

W: Some index files failed to download. They have been ignored, or old ones used instead.
W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main amd64 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-amd64_Packages)
W: Duplicate sources.list entry http://dl.google.com/linux/chrome/deb/ stable/main i386 Packages (/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_main_binary-i386_Packages)