No Ubuntu 14.04.3 LTS ao tentar executar o apt-get update, eu recebo isto:
Err http://us.archive.ubuntu.com trusty InRelease
Err http://us.archive.ubuntu.com trusty-updates InRelease
Err http://us.archive.ubuntu.com trusty-backports InRelease
Err http://us.archive.ubuntu.com trusty Release.gpg
Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com trusty-updates Release.gpg
Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.91.13 80]
Err http://us.archive.ubuntu.com trusty-backports Release.gpg
Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.91.13 80]
Err http://security.ubuntu.com trusty-security InRelease
Err http://security.ubuntu.com trusty-security Release.gpg
Unable to connect to security.ubuntu.com:http: [IP: 91.189.92.201 80]
Reading package lists... Done
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/trusty/InRelease
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/trusty-updates/InRelease
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/trusty-backports/InRelease
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/trusty-security/InRelease
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/trusty/Release.gpg Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/trusty-updates/Release.gpg Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.91.13 80]
W: Failed to fetch http://us.archive.ubuntu.com/ubuntu/dists/trusty-backports/Release.gpg Unable to connect to us.archive.ubuntu.com:http: [IP: 91.189.91.13 80]
W: Failed to fetch http://security.ubuntu.com/ubuntu/dists/trusty-security/Release.gpg Unable to connect to security.ubuntu.com:http: [IP: 91.189.92.201 80]
W: Some index files failed to download. They have been ignored, or old ones used instead.
Eu consegui atualizar e atualizar com êxito o apt-get nessa máquina no passado. Não tenho certeza do que mudou. Eu posso fazer o ping nos endereços bem. Estou usando 8.8.8.8 e 8.8.4.4 para DNS. Eu não estou usando um proxy.
verifique os seguintes casos:
verifique sua conexão com a internet.
pingando qualquer site (www.google.com), ele ajudará você a receber ou não os pacotes.
verifique se algum proxy está definido ou não.
verifique qualquer site nos navegadores (chrome / firefox)